TRIS(1,3-DIHYDROXY-2-PROPYL)AMINE, A PLANAR TRIALKYLAMINE: SYNTHESIS, STRUCTURE, AND PROPERTIES. A POTENTIAL PRECURSOR TO HYPERVALENT NITROGEN Except where reference is made to the work of others, the work described in this dissertation is my own or was done in collaboration with my advisory committee. This dissertation does not include proprietary or classified information __________________________ Yuanping Jie Certificate of Approval: ______________________________ ______________________________ Edward J. Parish Peter D. Livant, Chair Professor Associate Professor Chemistry and Biochemistry Chemistry and Biochemistry ______________________________ ______________________________ Susanne Striegler Thomas E. Albrecht-Schmitt Assistant Professor Associate Professor Chemistry and Biochemistry Chemistry and Biochemistry ____________________ Stephen L. McFarland Acting Dean Graduate School TRIS(1,3-DIHYDROXY-2-PROPYL)AMINE, A PLANAR TRIALKYLAMINE: SYNTHESIS, STRUCTURE, AND PROPERTIES. A POTENTIAL PRECURSOR TO HYPERVALENT NITROGEN Yuanping Jie A Dissertation Submitted to The Graduate Faculty of Auburn University In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Auburn, Alabama May 11, 2006 iii TRIS(1,3-DIHYDROXY-2-PROPYL)AMINE, A PLANAR TRIALKYLAMINE: SYNTHESIS, STRUCTURE, AND PROPERTIES. A POTENTIAL PRECURSOR TO HYPERVALENT NITROGEN Yuanping Jie Permission is granted to Auburn University to make copies of this dissertation at its discretion, upon request of individuals or institutions and at their expense. The author reserves all publication rights. _______________________________ Signature of Author _______________________________ Date of Graduation iv VITA Yuanping Jie, daughter of Chuanlin Jie and Xiulan Bao, was born on March 26, 1966, in Luan, Anhui province, the People?s Republic of China. She graduated with a Bachelor of Science degree in Chemistry in 1988 from Anhui Normal University. She received her M.S. degree in Organic Chemistry in 1991 from East China Normal University. From 1991 to 2001, she worked for Shanghai Chemical Reagent Research Institute. In 1991, she married Jie Liang, son of Huading Liang and Bangzhi Zhao. They have one daughter, Zhongling Liang. She entered the Graduate School at Auburn University, Auburn, Alabama in January, 2003. v DISSERTATION ABSTRACT TRIS(1,3-DIHYDROXY-2-PROPYL)AMINE, A PLANAR TRIALKYLAMINE: SYNTHESIS, STRUCTURE, AND PROPERTIES. A POTENTIAL PRECURSOR TO HYPERVALENT NITROGEN Yuanping Jie Doctor of Philosophy, May 11, 2006 (M.S., East China Normal University, 1991) (B.S., Anhui Normal University, 1988) 184 Typed Pages Directed by Peter D. Livant The hindered amine tris(1,3-dihydroxy-2-propyl)amine, 36, is a potential precursor to possible examples of nitrogen hypervalency. There are no simple, effective, and general methods to synthesize hindered tertiary amines. Extending previous work in our laboratory on Rh 2 (OAc) 4 -catalyzed insertions of carbenoids into N-H bonds, we achieved a synthesis of 36 in five steps and 49% overall yield. Starting from commercially available dihydroxyacetone dimer, our synthesis makes 36 available in multigram quantities. vi Some properties and structure of 36 have been studied. The pK a of 36 was found to be 3.08 ? 0.03, a low value for a tertiary amine. The X-ray crystal structure of 36 showed the nitrogen is essentially planar (sum of C-N-C angles 359.05(7) ?), and the average C-N bond length (1.454 ?) was shorter than normal. An explanation of this bond contraction is offered. The oxidation potential E 1/2 ox of 36 measured by cyclic voltammetry was found to be 0.88 V. The oxidation was reversible; oxidations of ordinary tertiary amines are usually irreversible. The X-ray crystal structure of 36?HCl revealed a severely flattened tetrahedral geometry about nitrogen (average H-N-C angle 102.3 ?). The reaction of 36 with boric acid led to a ?one- boron? compound, 67 (2,8,9- tris(hydroxymethyl)-5-bora-1-aza-4,6,11-trioxytricyclo[3.3.3.0 1,5 ]undecane) and a ?two-boron? compound, 69 (1,7-dibora-11-aza-2,6,8,14,15,17-hexaoxytetracyclo- [8.4.2.2. 7,12 0 4,11 ]octadecane). The X-ray crystal structure of 67 showed a dative bond between nitrogen and boron (1.6875(13) ?). Compound 69 is very hydrolytically unstable, but the X-ray crystal structure of a complex of 69 with pyridine confirmed the presence in 69 of two borons. The reaction of 36 with Z-Si(OEt) 3 (Z = Me, Ph) led to analogous "one-silicon" and "two-silicon" compounds. The X-ray crystal structures of both two-silicon compounds revealed a nearly symmetrical SiNSi array (Z = Me) and an unsymmetrical one (Z = Ph). vii ACKNOWLEDGMENTS I would like to express my heartfelt appreciation to my advisor Dr. Peter Livant. Not only has he given me invaluable academic guidance but also he has given my family much assistance. I thank all of my committee members for their time spent on this dissertation. I thank the faculty in the Chemistry and Biochemistry Department for their teaching. I thank my group members and my friends for their cooperation and help. Last but not least, I would like to thank my parents, my husband and my daughter for their support during this work. viii Style manual or Journal used: Journal of Organic Chemistry Computer software used: Microsoft Word 2000 and ChemDraw ix CONTENTS LIST OF TABLES............................................................................................................. xi LIST OF SCHEMES......................................................................................................... xii LIST OF FIGURES ......................................................................................................... xiii I. INTRODUCTION......................................................................................................1 1.1. Hypervalent bond????????????????????????.1 1.1.1.Three-center four-electron (hypervalent) bond???????????3 1.1.2. Extended hypervalent bond (5c-6e bond)????????????...8 1.2. Hypervalent compounds based on second row elements????????...10 1.3. Hypervalent nitrogen??????????????????????.15 1.3.1. Potential difficulties in forming hypervalent nitrogen???????..15 1.3.2. Some attempts to synthesize hypervalent nitrogen species?????..16 1.3.3. Ideas for the synthesis of precursors to hypervalent 10-N-5 species??18 1.3.4. New target precursor for 10-N-5 species????????????..22 I I. RESULTS AND DISCUSSION ..............................................................................26 2.1. The synthesis of tertiary amine 36?????????????????.26 2.1.1. Previous work in our lab??????????????????...26 2.1.2. The synthesis of compound 36 starting with dihydroxyacetone???...28 2.1.3. Some properties of tertiary amine 36??????????????39 2.2. Tris(1,3-dihydroxy-2-propyl)amine 36 incorporating x some main group elements????????????????????..49 2.2.1. Reactions of 36 with various sources of boron??????????.50 2.2.2. Reactions of 36 with various sources of silicon??????????64 2.3. Synthesis of tertiary amine 86???????????????????76 I I I. CONCLUSIONS?????????????????????????...79 I V. EXPERIMENTAL....................................................................................................81 V. REFERENCES..........................................................................................................96 V I. APPENICES ..........................................................................................................107 Appendix 1???????????????????????????..108 Appendix 2.???????????????????????????.117 Appendix 3..???????????????????????????126 Appendix 4..???????????????????????????140 Appendix 5.???????????????????????????.149 Appendix 6..???????????????????????????162 xi LIST OF TABLES 1. Some reactions of hindered secondary amines with diazo compounds catalyzed by Rh 2 (OAc) 4 ...........................................................................29 2. h for various trialkylamines .........................................................................................41 3. Structure parameters of 36 and some unhindered trialkylamines from x-ray crystallography ..........................................................................................43 4. Geometries of protonated trialkylamines.....................................................................46 5. The ?triple? hydrogen bonding interaction of some tertiary amine cations.................47 6. Geometric parameters of 67 and TEAB ......................................................................57 7. Geometric data of 71 from X-ray crystallography?????????????...62 8. Some structural feature of silatranes, ZSi(OCH 2 CH 2 ) 3 N???????????68 9. Some interesting structural parameters of 74, 76 compared to 80, 81 from x-ray crystallography ...........................................................................72 xii LIST OF SCHEMES 1. Modes of creation of a 3c-4e bond in pentacoordinate hypervalent molecules.........................................................................4 2. Failure to prepare 36 by reductive amination ..............................................................28 3. Initial investigations into the synthesis of 36...............................................................30 4. Route from dihydroxyacetone to tertiary amine 36 .....................................................32 5. Possible pathways in the reaction of 36 with (MeO) 3 B...............................................50 6. The reaction of 36 with H 3 BO 3 ....................................................................................60 xiii LIST OF FIGURES 1.1 The three-center four-electron bonding scheme for elements E and L ......................3 1.2 (a) Linear 3c-4e ? bonding scheme for F 3 ? (b) 3c-4e ?-bonding for the allyl anion.......................................................................................................6 1.3 Trigonal bipyramidal molecular structure of PF 5 .......................................................6 1.4 Pseudo-TBP molecular structure of PCl 4 F and SF 4 ...................................................7 1.5 Examples of the N-X-L designation system ...............................................................7 1.6 Approximate molecular orbital model of the 5c-6e bond ..........................................9 1.7 The synthesis of 10-C-5 compound 5 .......................................................................11 1.8 Hypervalent compounds with O-C-O pincer ligands ...............................................11 1.9 Precursors to O-C-O pincer ligands for synthesis of hypervalent carbon species .......................................................................................12 1.10 Some hypervalent carbon compounds with Akiba's O-C-O pincer ligands................................................................................................12 1.11 The synthesis of hypervalent boron species..............................................................13 1.12 Synthesis of hypervalent boron compounds 19 ........................................................14 1.13 Synthesis of hypervalent boron compounds 20 .......................................................14 1.14 Conceptual steps in the conversion of an 8-N-3 species to a 10-N-5 species...................................................................................................19 2.1 Complex of dirhodium tetraacetate with Lewis base B............................................35 2.2 NMR spectra of compound 36 in D 2 O......................................................................38 2.3 The X-ray crystal structure of compound 36 ............................................................40 xiv 2.4 Orbital interaction diagram for an N-CHA 2 fragment ..............................................43 2.5 Comparison of basicities of 36 and other trialkylamines..........................................44 2.6 The X-ray crystal structure of compound 36?HCl ....................................................45 2.7 Oxidation potentials (E 1/2 OX ) of several sterically congested trialkylamines...........................................................................................47 2.8 NMR spectra of reaction of 36 with (MeO) 3 B..........................................................52 2.9 NMR spectrum of reaction of 36 with boric acid .....................................................54 2.10 X-ray crystal structure and some structural data for TEAB .....................................55 2.11 X-ray crystal structure of one-boron compound 67..................................................56 2.12 X-ray crystal structure of compound 71 ...................................................................61 2.13 NMR spectra of compound 75????????????????????..66 2.14 NMR spectra of compound 77????????????????????..67 2.15 X-ray crystal structure of compound 74 ...................................................................70 2.16 X-ray crystal structure of compound 76 ...................................................................71 2.17 NMR spectra of compound 82????????????????????..75 2.18 NMR spectra of compound 85????????????????????..78 1 INTRODUCTION The Octet Rule which was provided by Lewis 1 and Langmuir 2 has been considered a central dogma governing chemical bonding in organic molecules for a long time. The Octet Rule means molecular electron bonds are most stable when the atoms achieve a no- ble gas configuration. However, it is clear that this rule has its limitations. For example, PCl 5 has ten electrons about the phosphorus. More surprisingly, XeF 4 and XeF 2 were synthesized by Claassen, Selig, and Malm 3 in 1962. According to the Octet Rule, the rare-gas atoms should be inert due to their full valence shells. The Octet Rule has never been able to provide a good theoretical treatment for such compounds. Obviously a new theory to explain these compounds was needed. 1.1 Hypervalent bond In 1969, J. I. Musher 4 established the concept of hypervalent molecules: they are ions or molecules having elements bearing more electrons than the octet (nine or more) within a valence shell. He also suggested there were two methods to form hypervalent bonds: (1) make up a dsp 3 or d 2 sp 3 orbital by hybridization using higher-lying d orbitals or (2) make up highly ionic orbitals revising (modifying) the basic idea of Lewis that a bond is formed by a localized pair of two electrons. The expansion of the octet has traditionally been explained by participation of d or- bitals in hybridization. Smith and coworkers 5 used the experimentally determined bond lengths of XeF 2 and XeF 4 to support covalent models with ten electrons in the xenon 2 valence shell of XeF 2 , and twelve electrons in the xenon valence shell of XeF 4 . In expla- nation of the bonding schemes, they used the then-popular theory of an sp 3 d hybridized configuration for XeF 2 , and sp 3 d 2 hybridized configuration for XeF 4 . d-Orbitals cannot be utilized to hold extra electrons if the energy gap between n(sp) and n(d) is too large. The second row elements (i.e. Li ? Ne) have high-energy d orbitals, therefore traditionally hypervalency has been thought possible only for third row elements (i.e. Na ? Ar) and beyond. In 1951, Pimentel 6 and, independently, Rundle 7 set up the basis for new develop- ments in this area by proposing the idea of a three-center four-electron (3c-4e) bond, em- ploying molecular orbital theory. However, the idea of a 3c-4e bond was widely ignored initially. It gradually came to be used only when d orbital hybridization apparently could not be supported. So Pimentel and Spratley 8 refuted the conclusions that Smith and co- workers had drawn about covalent models for XeF 2 and XeF 4 , and they insisted that the bonding scheme involved the 3c-4e interaction. Later, Musher 4 further developed the theory of hypervalent bonding that Pimentel had proposed in 1951, and introduced hybrid orbital wave functions, atomic "geminals," for this type of bond. Schleyer and Reed 9 in- vestigated the bonding of hypervalent molecules theoretically and reached the conclusion that employing dsp 3 or d 2 sp 3 is not at all correct and rather misleading. Through this and the efforts of Kutzelnigg and coworkers, 10 the idea of a 3c-4e bond has become supported and is now generally accepted. 1.1.1 Three-center four-electron ("hypervalent") bond A 3c-4e bond is formed from three adjacent p-type atomic orbitals arranged in a line with lobes lying along the internuclear axis. These overlap in a ?-fashion to form three molecular orbitals (see Figure 1.1). Two electrons are in a bonding molecular orbital and two are in a nonbonding orbital. ?According to the fundamental description of a 3c-4e bond, one pair of bonding electrons is delocalized to the two ligands (substituents), Bonding Occupied Non-Bonding Occupied Anti-Bonding Unoccupied E L L E L L E L L Figure 1.1. The three-center four-electron bonding scheme for elements E and L resulting in the charge distribution of almost ?0.5 charge on each ligand and almost +1.0 charge on the central atom.? 11 In order to experimentally construct a 3c-4e bond in penta- coordinate hypervalent molecules, four ways were proposed by Akiba 11,18 (Scheme 1). (1) Add two free radicals from ligands to combine with an unshared pair of electrons in the central atom's p-orbital. (2) Add two unshared pairs of electrons to coordinate to a central atom?s vacant p-orbital. (3) Add a pair of unshared electrons of one ligand to the ? * or- bital of a Z?X bond in a cationic molecule. (4) Add a pair of unshared electrons of one ligand to the ? * orbital of a Z?X bond of a neutral molecule (e.g., silicon compounds). 3 X YZ (1) X YZ (2) + XZ Y + (3) XZ Y (4) Scheme 1 Modes of creation of a 3c-4e bond in pentacoordinate hypervalent molecules When X is carbon, method (4) is similar to the transition state of the S N 2 reac- tion.Therefore sometimes hypervalent compounds are referred to as "frozen transition states." For example, pentacoordinate hypervalent carbon compound 1 16 and boron compound 2 17 correspond to method (2) above. MeO C OMe MeO B OMe OMeMeO X X + B 2 F 7 - 12 Compared to a normal covalent bond (i.e. a 2c-2e bond) in which no electrons occupy any nonbonding or antibonding orbitals, in a 3c-4e bond the nonbonding molecular or- bital is the highest occupied molecular orbital (HOMO). A 3c-4e bond is referred to as an electron-rich, orbital-deficient bond. A hypervalent bond will be weak and long in com- parison with a normal covalent bond. As implied in the hypervalent bonding scheme of Figure 1.1, appreciable electron density is strongly localized on the axial ligands. The 4 5 apical bond is much more polarized than the equatorial ones. Thus the axial ligands should be electron?withdrawing groups while the central atom must be comparatively electropositive for the purpose of stabilizing the electron density distribution. Some cal- culated data and experimental evidence on phosphorus hypervalent compounds (PH x F 5- x , 14 PCl x F 5-x 15 ) supported this aspect of hypervalent bonding theory. In all of these phos- phoranes the axial positions were occupied with fluorines in preference to hydrogens or chlorines. The 3c-4e bond model was first applied to trihalide ions (X 3 ? , XY 2 ? , and XYZ ? ) and bifluoride ion (HF 2 ? ) by Rundle. 7 It was able to explain that the trihalide ions were linear and the bonds were slightly longer and presumably slightly weaker than the correspond- ing ordinary halogen-halogen bonds. For example, the I?I bond length (1.16 ?) of I 3 ? is longer by 10% than that of diiodine (1.06 ?). In 1985, Martin 12 and coworkers used the 3c-4e molecular orbital model for F 3 ? , which should be a quite unstable hypervalent com- pound. The three-center bonding scheme for the trifluoride anion is shown in Figure 1.2(a). The ??delocalized orbitals involving ? overlap of p?orbitals are analogous to the three-center bonding in the allyl anion (Fig. 1.2(b)). Three-center bonding like that shown in Figure 1.2(a) is sometimes called a "?-allyl" system. The structure of F 3 ? was calcu- lated at two levels (DZP (a polarized double-? set)/ACCD (approximate coupled clusters with double substitutions) and TZP (a polarized triple-?)/ACCD). In both cases the structure of F 3 ? was found to be linear with equivalent bonds. At the DZP/ACCD level, the F?F bond length was calculated to be 1.711 ?, while at the TZP/ACCD level it was 1.701?, which was about 0.3 ? longer than that of F 2 (F?F: 1.412 ?). The bonding in F 3 - FFF - H 2 CCHCH 2 - ? 1 ? 2 ? 3 (a) (b) Figure 1.2 (a) Linear 3c-4e ? bonding scheme for F 3 ? (b) 3c-4e ?-bonding for the allyl anion. could be described as a 3c-4e bond involving only p-orbitals. In agreement with this is the ACCD charge distribution in the ion (F 3 - ), which puts a ?0.51 charge on each apical fluorine and a +0.03 charge on the central fluorine. Normally hypervalent molecules have a trigonal bipyramidal (TBP) or pseudo TBP geometry 13 that employs two types of bonding: hypervalent bonding for the two axial ligands, and normal covalent bonding to the equatorial ligands. The molecular structure of PF 5 in Figure 1.3 is an example of true TBP geometry. It is composed of three P?F bonds in the equatorial plane and one axial 3c-4e bond. The apical (or axial) bond (1.577 ?) is longer and weaker than the equatorial bond (1.534 ?). FP F F F F 1.577 ? 1.534 ? Figure 1.3 Trigonal bipyramidal molecular structure of PF 5 6 But the term pseudo TBP is most employed to describe hypervalent species because most hypervalent species have a distorted TBP geometry. This may be the result of one or more ligands being different than the others, or one or more ligands being replaced by a lone pair of electrons. This is illustrated in Figure 1.4. S F F F F 101.5? 187? Cl P Cl Cl Cl F 90.9? Figure 1.4 Pseudo-TBP molecular structure of PCl 4 F 20 and SF 4 19 The N?X?L designation 21 is a convenient notation system to describe the structure of hypervalent species: N represents the number of electrons associated with the valence shell of the central atom, X is the symbol of the central atom (Groups 1,2 13?18), L is the number of ligands directly bonding the central atom X. In general, hypervalent com- pounds are those compounds with N > 8, i.e. the octet is expanded. According to the N?X?L designation, multiple bonds are counted as polarized single bonds no matter the actual character of the bonds. Following are some examples to illustrate the N-X-L system. (Figure 1.5). F F F Xe F F O ? O ? 2+ F F ? O F F Xe F F F F F F Cl - F F F F F F I F 10-F-2 12 10-Br-3 22 10-Xe-4 23 12-Xe-5 24 14-Cl-6 25 14-I-7 26 _ Br O O CF 3 F 3 C CF 3 F 3 C Figure 1.5 Examples of the N-X-L designation system 7 8 1.1.2 Extended hypervalent bond (5c?6e bond) In 1988, Farnham 27 and coworkers reported that tris(dialkylamino)sulfonium per- fluoro-2-methyl-2-pentyl carbanion reacted with perfluoroalkyl iodides (R f I) to give a novel structure of the form [R f ?I?F?I?R f ] - . The crystal structure analysis and high?level ab initio calculation proved that bonding in this form was a five?center, six?electron hy- pervalent ? bond with fluorine at the central position, not an ion?dipole complex. In the calculations of Farnham et al. on this 5c?6e bond, the negative charge was localized at the central and terminal positions. In order to stabilize a 5c?6e bond, the central and ter- minal positions should be occupied by the more electronegative elements, with less elec- tronegative elements at the other two positions. In the 3c?4e bond only the terminal posi- tions should be occupied by electronegative elements and the central position by more electropositive atoms. The electronic density distribution of the 5c?6e bond differs from that of the 3c?4e bond. So Farnham et al. called the 5c?6e bond an extended hypervalent ? bond. In 1989, Dixon 28 et al. gave other examples of 5c?6e hypervalent bonding, i.e. [Xe 2 F 3 ] + ([F-Xe-F-Xe-F] + ) and XeIF 3 (F-Xe-F-I-F). The electronic structures of [Xe 2 F 3 ] + and Xe 2 IF 3 were calculated by using ab initio molecular orbital theory with polarized, split-valence basis sets. Anthraquinone 3 and 9?methoxyanthracene 4 were synthesized by Nakanishi 29 and coworkers. The structures of 3 and 4 were determined by X-ray crystallography, which revealed the linear alignment of five C? Se???O???Se? C atoms in 3a and 4a. The Se-O distances in 3a and 4a are 2.673?2.688 ? and 2.731?2.744 ? respectively, which are about 25% shorter than the sum of van der Waals radii of the atoms. This evidence strongly supported the extended hypervalent [? * (C i ? Se)???n p (O)???? * (Se? C i )] 5c?6e O O SeSe YY R SeSe YY 3a Y = H 3b Y = Cl 4a (R = OMe, Y = H) 4b (R = H, Y = H) 4c (R = H, Y = Cl) interactions in 3a and 4a. They suggested that 5c?6e bond should be constructed by the combination of the two hypervalent n p (O)???? * ( Se? C i ) 3c?4e interactions through the central n p (O). The quantum chemical calculations performed on 3a, 4a and 4b suggested that the origin of the linear alignment of the five C? Se???O???Se? C atoms in 3a and 4a was stabilization due to 5c-6e extended hypervalent 5c?6e bonding. An approximate molecular orbital model which summarizes Nakanishi's ideas is shown in Figure 1.6. 29 ? 1 ? 3 ? 5 ? 2 ? 4 E Figure 1.6 Approximate molecular orbital model of the 5c-6e bond 9 10 1.2 Hypervalent compounds based on second row elements Since Claassen, Selig, and Malm 3 synthesized the xenon fluorides in 1962, there have been many papers published dealing with either the synthesis of new hypervalent species, the calculated and experimental geometries of hypervalent compounds, or descriptions of hypervalent bonding schemes. Especially in the past twenty years, many different hyper- valent compounds of elements from the third row or below were synthesized and stud- ied. 11 However, by contrast, just a few hypervalent compounds based on second row ele- ments were synthesized or even detected. Only hypervalent compounds of boron, carbon, and fluorine have been reported, and there exist only a few examples of these com- pounds. The first 10-F-2 hypervalent fluorine species was reported by Ault and Andrew 30 in 1976. It was the highly unstable trifluoride anion F 3 - generated by simultaneous deposi- tion of an Ar/F 2 mixture with CsF, RbF or KF. All three alkali metal trifluorides (M + F 3 - ) were detected at low temperature by Raman and infrared spectroscopy. The chemists most successful at synthesizing and characterizing second row hyper- valent species of carbon and boron are J. C. Martin and Kin-ya Akiba. They have pre- pared and characterized a series of compounds with boron and carbon hypervalent cen- ters. In 1979, Forbus and Martin 31 used the reaction in Figure 1.7 to prepare the first di- rectly observable pentavalent carbon species (10?C?5), an analogue to the transition state in the Walden inversion mechanism. 1 H NMR spectroscopy and, in the case of X = F, 19 F NMR spectroscopy were used to confirm that the structure of 5 was the symmetrical trigonal bipyramidal geometry, not an unsymmetrical 8?C?4 species, such as 6. Ph OH Ar OH SS XX S + XX Ph E E S + C + - 5, E = OMe TfO - TfO - liquid SO 2 CF 3 SO 3 H -80 ?C Ar = 2,6-dimethoxyphenyl S XX Ph E E S + C + 6, E = OMe TfO - TfO - Figure 1.7 The synthesis of 10-C-5 compound 5 31 Whereas very useful trianionic OCO pincer ligands (Figure 1.8) have been used to synthesize hypervalent phosphorus, sulfur, and iodine species, 32 application of these ligands to prepare hypervalent species from second row elements hasn't been reported. XL n O O XL n O O OO XL n O O O XL n O O F 3 C F 3 C CF 3 CF 3 Figure 1.8 Hypervalent compounds with O-C-O pincer ligands 33 Recently, Kin-ya Akiba and coworkers designed new kinds of ligands (Figure 1.9) for synthesis of a series of hypervalent carbon compounds (Figure 1.10) and boron species. 34 NMR spectra were used to confirm these hypervalent carbon species 10 - 12. In addition, Akiba and coworkers were able to obtain crystals of 10 and 12. X-ray analysis 11 MeO OTf OMe MOMO Li OMOM Br OAr 1 Ar 1 O Ar 1 = p-Tol, p-CH 3 C 6 H 4 7 16,34 8 33,34 9 18 Figure 1.9 Precursors to O-C-O pincer ligands for synthesis of hypervalent carbon species MeO C OMe MeO C OMe C Ar 1 = p-Tol, p-CH 3 C 6 H 4 Ar 2 = Ph, p-FC 6 H 4 , p-ClC 6 H 4 , p-MeOC 6 H 4 10 16,33,34 11 34 12 18 OMeMeO + + Ar 1 O OAr 1 Ar 2 Ar 2 Figure 1.10 Some hypervalent carbon compounds with Akiba's O-C-O pincer ligands showed a symmetrical structure (10-C-5) where the two C-O distances were almost iden- tical, and longer than that of a covalent C-O bond, but shorter than the sum of the van der Waals radii. The first hypervalent boron compounds were reported by Lee and Martin 35 in 1984 (Figure 1.11). They used pyridine diol 13 as starting material to synthesize isolable 10-B- 5 and 12-B-6 hypervalent boron species 16 and 17. 1 H-, 13 C-, and 19 F-NMR were all used to confirm the structures of 16 and 17, but the very important evidence in support of these geometries was 11 B NMR chemical shifts. Compounds 16 ( 11 B NMR, -20.1 ppm) and 17 12 ( 11 B NMR, -122.9 ppm) both displayed 11 B chemical shifts much farther upfield than any chemical shifts previously observed for 8-B-4 type compounds. N R CF 3 HO CF 3 F 3 C OH F 3 C N R CF 3 LiO CF 3 F 3 C OLi F 3 C N + R CF 3 O CF 3 F 3 C O F 3 C B ? Cl BCl 3 4h 25 ?C n-BuLi 0 ?C ether 13 14 15 N + R F 3 C O CF 3 F 3 C O CF 3 B 2- Et 4 N + 16 N + R F 3 C O CF 3 F 3 C O CF 3 B 3 - N + O O CF 3 CF 3 CF 3 CF 3 R Et 4 N + 17 2) Et 4 NCl, CH 2 Cl 2 Li Li Et 4 NBr 1) 14, 110 ?C, 4 h Figure 1.11 The synthesis of hypervalent boron species 35 The first fully characterized hypervalent boron species was reported in 2000 by Akiba and coworkers. 36 As shown in Figure 1.12, they used the versatile tridentate anthracene ligand 18 to synthesize hypervalent (10-B-5) boron compounds 19. Crystals of 19a-19c for X-ray analysis were obtained. The X-ray analysis showed the sum of the bond angles around the central boron of 19 are all 360.0?, which means that in each case the central boron atom is planar with sp 2 hybridization. The two B-OMe bond lengths are identical (2.436 ? in 19c) or almost identical (2.379 ? and 2.441 ? in 19a, 2.398 ? and 2.412 ? in 13 MeO Br OMe 18 MeO B OMe 19a: X = O, Y = H 19b: X = O, Y = OMe 19c: X = S, Y = H XX Y n-BuLi X B X Y Cl Figure 1.12 Synthesis of hypervalent boron compounds 19 19b). These bond lengths are longer than those of covalent B-O bonds (1.394 - 1.400 ?), 36 but shorter than the sum of the van der Waals radii (3.48 ?). 37 Recently, hypervalent boron compounds 20a-20c were synthesized by Akiba and coworkers as shown in Figure 1.13. 34 The results of X-ray crystallographic analysis of 20a-20c were very interesting. The structures of 20a and 20b were almost symmetrical, the two B-O distances almost identical. MeO Br OMe n-BuLi a) B(OMe) 3 or b) BF 3 or c) BCl 3 MeO B OMe 20a: X = OMe 20b: X = F 20c: X = Cl XX Figure 1.13 Synthesis of hypervalent boron compounds 20 34 14 15 1.3 Hypervalent nitrogen 1.3.1 Potential difficulties in forming hypervalent nitrogen There have been three major reasons advanced for the reluctance of second row ele- ments to expand their valence octet: (i) steric hindrance, (ii) high electronegativity and high first ionization potentials, and (iii) an inability to utilize d-orbitals. The inability to utilize d-orbitals in the bonding scheme of second row elements has been cited in many papers as the reason second row elements are resistant to becoming hypervalent. 14, 38-42 But both quantum calculations and experimental results have proved that the role of d-orbitals in hypervalent bonding is not as crucial as many had thought. 9,10,38,40,42 For sulfur hexafluoride, Reed and Weinhold 43 found that the d-orbital contribution to the bonding system is small. 14,38-42 They commented, ?The total 3d popu- lation in SF 6, however, is only around 0.25e, the 3d ? population (0.16e) being only one- sixth of what would be required for sp 3 d 2 hybridization on sulfur?.We therefore concur with the suggestions of MacLagan and Kutzelnigg that models of sp 3 d and sp 3 d 2 hyper- valent bonding in non-metals should no longer be taught in chemistry courses.? Steric hindrance is another reason for the failure of second row elements to bond to five or more ligands. The second row elements have very small atomic radii and the re- pulsion between the ligands is very strong. Also harmful to the possible hypervalency of second row elements is their very high first ionization potentials, which means second row elements are reluctant to donate electrons to the axial ligands as shown in the hypervalent bonding scheme of Figure 1.1. Compared to carbon and boron, nitrogen has a smaller atomic radius and higher first IP. These could be reasons that the syntheses of hypervalent species of nitrogen are particularly difficult. Fluorine has a smaller atomic radius and higher first IP than nitro- gen. But a hypervalent fluorine is required to coordinate only two ligands linearly (e.g. F 3 - ). The lack of steric repulsion between ligands in F 3 ? may in fact overcome the desta- bilizing effects of having a highly electronegative central atom. As previously discussed, hypervalent carbon, boron, and fluorine species have been observed, but evidence for a hypervalent nitrogen species or even transient hypervalent nitrogen species 41,44 have been very difficult to obtain. 1.3.2 Some attempts to synthesize hypervalent nitrogen species In 1916, Schlenk 45 believed he had synthesized pentacoordinate pentavalent nitrogen as in the following equations. But he failed. Ph 3 CNa + Me 4 NCl Ph 3 C-NMe 4 [1] PhCH 2 Na + Me 4 NCl PhCH 2 NMe 4 [2] Ph 2 NK + Me 4 NCl Ph 2 N-NMe 4 [3] In 1947, Wittig 46 also tried to make a hypervalent nitrogen species as in equation 4. He got nitrogen ylides instead of hypervalent nitrogen species. Fortunately, this led to the eventual discovery of phosphorus ylides. PhLi + Me 4 N + Cl ? Ph-NMe 4 Me 3 NCH 2 + [4] 16 Hellwinkel and Seifert 47 thought it should be possible to add a fifth ligand to an am- monium salt lacking ?-hydrogens as in equation 5. The experimental results showed that they were not successful. N I ? + N Ph N PhLi [5] Nishikida and Williams 48 reported a 9-N-4 species, trifluoramine oxide radical anion F 3 N ? -O ? , in which the three fluorines were equivalent. It was detected and identified by a second-derivative ESR spectrum of a ?-irradiated solid solution of 5 mol % F 3 NO in SF 6 recorded at ?170 ?C after irradiation at ?190 ?C. However, this radical anion is only sta- ble at very low temperature. It loses F ? above 102 K to form F 2 N-O ? . Hypervalent ammonium radicals (9-N-4), in which the nitrogen atoms have nine va- lence electrons, were reported by Scott et al. 49 Transient organic hypervalent ammonium radicals were produced in the gas phase by one-electron reduction of their ammonium ion counterparts, via collisional electron transfer (equation 6). Neutralization-reionization mass spectrometry was used to investigate hypervalent ammonium radicals and to study their dissociations. 17 N R R R R + M M + N R R R R - R? N R R R R = H, alkyl, aromatic ring M = Na, K, dimethyl sulfide [6] 9-N-4 NF 5 (10-N-5) was speculated to be formed from NF 3 -F 2 either by fission-fragment ra- diolysis at room temperature 50 or irradiation by 3-MeV bremsstrahlung at ?196 ?C 51 or from NF 4 AsF 6 by pyrolysis at 175 ?C. 52 However, in 1988 Christe, et al. 53 summarized all previous attempts, and finally concluded that five fluorines do not have enough space to bond to nitrogen. That means the repulsion between fluorines in NF 5 is very strong. However, Grohmann and coworkers recently discovered compound 21. 54 The nitrogen atom in 21 is in the center of a trigonal bipyramidal cluster of five gold atoms. The gold- gold interactions are presumably attractive. The nitrogen is hypercoordinate, not hyper- valent. N Au Au Au Au Au Ph 3 P Ph 3 P PPh 3 PPh 3 PPh 3 2+ 2 BF 4 ? 21 1. 3. 3 Ideas for the synthesis of precursors to hypervalent 10-N-5 species From the previous review, one might wonder whether it is possible to synthesize a hypervalent nitrogen species. In our group, we have long been interested in seeing whether nitrogen can be made to form 10-N-5 systems. To design such a system is chal- lenging. 18 a) Planarity at nitrogen. According to the hypervalent bonding scheme shown in Figure 1.1, oxidizing an 8-N-3 species to a 10-N-5 species involves changing the geome- try at nitrogen as shown in Figure 1.14. Changing the pyramidal geometry of nitrogen to the planar geometry (step 1, Figure 1.14) will impose an energy cost. However, if one were to begin with an amine having a planar ground state geometry, step 1 and its energy cost would be eliminated. N R R R NR R R NR R R Z Z NR R R Z Z 1 32 Figure 1.14 Conceptual steps in the conversion of an 8-N-3 species to a 10-N-5 species We know some amines have a planar geometry. For examples, the nitrogen atoms in following amines all have a planar geometry. The bicyclo[3.3.3]undecane system is an N N N N N N N N N O O O N O CF 3 CF 2 N CF 2 CF 3 CF 2 CF 3 N H 3 C H 3 C CH 3 CH 3 CH 3 CH 3 22 55 23 56 24 57 27 60 26 59 25 58 19 obvious motif in 22, 23, and 24. So some confidence can be gained that synthesizing some precursors of 10-N-5 species including a planar nitrogen geometry is a possible goal, although it may turn out to be an elusive one requiring either extreme ingenuity or conditions. b) Suitable axial ligands. As discussed, a 3c-4e bond has an accumulation of partial negative charge on the apical ligands and partial positive charge on the central atom. This charge distribution can be stabilized by using very electronegative apical ligands. Obvi- ously, each apical ligand must have an orbital capable of good overlap with that of the central element. Not only should the central atom be more electropositive in order to sta- bilize the partial positive charge on the hypervalent atom, but the equatorial ligands should be electropositive for the same purpose. c) Five-membered ring effect. Westheimer found that 10-P-5 species in which a five-membered ring that included an apical and an equatorial ligand in the trigonal bipyramidal geometry were several orders of magnitude more stable than model 10-P-5 species in which the five-membered ring was absent. 61 This has been called the ?five- membered ring effect.? Martin, et al. found the ?five-membered ring effect? was also manifested in sulfurane (10-S-4) chemistry. 62 The evidence for ?five-membered ring ef- fect? was tested by a series of hydrolysis experiments. Sulfurane 28 is extremely reactive S OR f OR f OR f = OC(CF 3 ) 2 Ph 28 + H 2 O very fast Ph 2 S=O + 2 HOR f [7] 20 toward water, producing the hydrolysis products alcohol and sulfoxide very fast at low temperature (eq. 7). 63 However, sulfurane 29 hydrolyzes very slowly (eq. 8), and 30 does not hydrolyze even after refluxing for two hours in HCl solution or aqueous sodium hy- droxide (eq. 9). 62f,64 Kinetic and calorimetric 65 studies showed that the five-membered S O OR f F 3 C CF 3 29 + H 2 O slow S OH F 3 C CF 3 + HOR f [8] O S O O CF 3 F 3 C CF 3 F 3 C 30 + H 2 O H + or OH ? reflux no reaction [9] ring effect provided 10-12 kcal/mol stabilization for pseudo TBP sulfuranes such as 30 relative to acyclic analogue 28. So the use of a bidentate ligand or ligands to form a five-membered ring spanning an apical and an equatorial position in a TBP geometry would be extremely useful. We think that it is wise to include the five-membered ring effect in one?s design of a 10-N-5 spe- cies, guessing that the species will have a TBP or pseudo-TBP geometry. d) Framework to ensure collinear Z-N-Z array. We require to hold atoms above and below nitrogen at a distance suitable for bonding to nitrogen. Our idea is to trap ni- trogen in a pre-formed pseudo TBP structure. 21 According to these considerations, Dr. John Northcott, a former student in our group, synthesized compound 31, which reacted with excess THF?BH 3 complex to produce 32. 66 OH OH HO HO N HO OH BH 3 ?THF O O O O N O O B B B O O O O O B O N O 31 32 33 In fact, x-ray crystallography showed 32 contained a THF of crystallization as shown in 33. Unfortunately, it was impossible to prepare 32 free of coordinating solvent, so it could not be determined experimentally whether this B-N-B array is intrinsically 34 or 35. The ab initio calculations indicated that the system 34 (with the symmetrical 3c-2e [B???N???B] array) is only 2.66 kcal/mol higher in energy than the system 35 (with the un- symmetrical [B-N B] array). BO O O O O B O N B O O O O O B O N 34 35 1.3.4 New target precursor for 10-N-5 species. a) Precursor 36 for 10-N-5 species Compared to 31, the symmetry of 36 should be higher than 31 and should have less steric hindrance. So we think 36 may be a better precursor for 10-N-5 species. Compound 22 36 is an extension of the well-known triethanolamine, 37. Reaction of suitable reagents with the three hydroxy groups of triethanolamine produces so-called"atranes" 38 or 39 N OHHO HO HO OH OH 36 N OH HO OH 37 (E = B, Al, Si, P, Sn, Ge, etc.). Compounds 38 and 39 have been made and there has been much discussion about the length of the dative bond made between nitrogen and the other (E = Si, Ge)(E = B, Al, P) 3938 E N O O O E N O O O Z heteroatom, the geometry enforced by this fourth bond, and the properties. 67 We hope 36 could incorporate some main group elements just like triethanolamine to provide 40 and 41. As mentioned before, molecules like 40 or 41 may have a static unsymmetrical structure 42, a static symmetrical structure with a 3-center bond 43 or a dynamic struc- ture. Compounds 40 and 41 are ?-allyl cation analogues. To create the possibility of nitro- gen hypervalency, two electrons must be added to 40 (or 41) to become ?-allyl anion analogues in which N is engaged, in a formal sense, in five single bonds. 23 (E = Si, Ge) (E = B, Al, P) 41 40 E N O O O O O O E E N O O O O O O E Z Z N OH HO HO HO OH HO 36 "EX 3 " "Z-EX 3 " + 6 HX + 6 HX N O O O E O O O E N O O O E O O O E N O O O E O O O E N O O O E O O O E 42 43 b) Precursor 45 for 10-N-5 species As discussed, the five-membered ring as a design element seems like a good idea. How about a six-membered ring? In view of Alder?s studies of ring size effects on bridgehead- bridgehead interactions in bicyclic compounds, 68 it may be well to explore variants of the proposed systems in which other ring sizes are present. One example, 46 (or 47), and its precursor 45 are shown. 24 40 44 10-N-5 2- 2- 2 e ? ? E N O O O O O O E E N O O O O O O E E N O O O O O O E N N N E N N E N H H H H H H N 46 N NH 2 NH 2 H 2 N NH 2 H 2 N H 2 N 45 N N N E N NE N H H H H H H N 47 Z Z or EX 3 or Z-EX 3 25 RESULTS AND DISCUSSION 2.1 The synthesis of tertiary amine 36. 2.1.1 Previous work in our lab. Tertiary amine 36 can be regarded as an analogue of triisopropylamine, which is among the most sterically hindered tertiary amines prepared to date. 70 There are only a few reported syntheses of triisopropylamine, and most of them required rather harsh con- ditions. 60,70,71 There are many methods for the synthesis of hindered secondary amines, but there are few general methods available for the preparation of extremely hindered tertiary amines, and these give the hindered amine product in low or modest yields. In 2001, Minmin Yang et al. 72 collected all reported routes to such compounds. These are shown in equations 10 - 15. There seems to be no simple, general method for the synthe- sis of extremely hindered tertiary amines. In fact, many approaches for synthesizing terti- ary amine 36 in our laboratory were fruitless. 77 NH 2 O SO 2 2 2 1) 110 ?C, 2 h 2) 140 ?C, 2 h 3) 160 ?C, 16 h N 18% [10] 70,71 + [11] 60 NH 2 + Cl ? 2 1) KCN 2) CH 3 CHO N CN MeMgBr N 17% 26 [12] 73 N 44% N H 3 CO H 3 CO + 2 EtMgBr [13] 74 NH 2 + 2 Br O N H + N O N H 17% 0 ?C NaOH [14] 75 + N H EtO 2 C EtO 2 C TfO CO 2 Et N EtO 2 C EtO 2 C CO 2 Et 32% CH 3 NO 2 reflux [15] 76 N O H N 74% N + Cl H COCl 2 Cl ? 2 CH 3 Li In 1999, Scott, Kr?lle, Finn, Nash, Winters, Asano, Butters and Fleet ("SKFNWABF") 78 also failed to synthesize 36 (Scheme 2). As shown in Scheme 2, dihy- droxyacetone dimer 48 underwent reductive amination to produce intermediate primary amine 49, secondary amine 50, but not hindered tertiary amine 36. So tertiary amine 36 would be expected to be a challenging synthetic target. Fortunately, recent work in our laboratory 79 pointed to a possible synthesis of tertiary amine 36. That work involved the Rh-stabilized carbene N-H insertion reaction (eq. 16). 80 Using this reaction, it was possible to produce sterically hindered tertiary amines, a N R H R N 2 R' R' N R R R' R' H Rh 2 (OAc) 4 + [16] 27 facet of this reaction which had been previously unexplored. In our laboratory, we have been exploring carbenoid N-H insertion into various congested secondary amines. Some results are shown in Table 1. 72,81 These results gave us confidence that the N-H insertion methodology might be used successfully to prepare 36. Scheme 2 Failure to prepare 36 by reductive amination 48 OH OH O OH OH H 2 N NH 4 Cl, NaBH 3 CN MeOH, HOAc 49 OH OH N H HO HO 50 NH 4 Cl MeOH NaBH 3 CN HOAc OH OH N HO HO OHOH 36 O O OH OH HO HO 2.1.2 The synthesis of compound 36 starting with dihydroxyacetone Based on SKFNWABF's work 78 and previous work in our laboratory, we decided to use cheap, commercially available dihydroxyacetone as the starting material. Our work in realizing this plan is shown in Scheme 3. We envisioned making secondary amine 50 by reductive amination (see Scheme 2) and using a carbenoid N-H insertion to complete the carbon skeleton of 36. 28 Table 1. Some reactions of hindered secondary amines with diazo compounds catalyzed by Rh 2 (OAc) 4 NH 2 CO 2 Me CO 2 Me N 2 N 2 CO 2 Me CO 2 Me 73% 72 NH 2 CO 2 Me CO 2 Me N 2 N 2 CO 2 Me CO 2 Me 85% Ph N H Ph CO 2 Me CO 2 Me N 2 N 2 O O 51 51 51 52 Ph N H Ph Ph N Ph CO 2 Me CO 2 Me Ph N Ph O HO 75% 81 84% 72 Ph N H OMe CO 2 Me CO 2 Me N 2 N 2 O O 51 52 Ph N H OMe Ph N OMe CO 2 Me CO 2 Me 78% 72 Ph N OMe O HO 70% 81 Amine Diazo compound Product Isolated yield Ref. 72 In order for the N-H insertion to succeed, the OH groups must be protected. We ini- tially decided to protect the OH groups prior to the reductive amination. SKFNWABF's method for preparing 50 using unprotected dihydroxyacetone involved ion exchange chromatography to isolate the water-soluble product. We felt that OH-protected 29 O HO OH 48 O TBDMSO OTBDMS 55 TBDMSCl a imidazole DMF N HO OH HO OH H NH 4 Cl, NaBH 3 CN CH 3 CO 2 H, MeOH 50 NaBH 3 CN, NH 4 Cl MeOH, CH 3 CO 2 H N TBDMSO OTBDMS TBDMSO OTBDMS H 56 TBDMSCl a imidazole DMF N TBDMSO OTBDMS TBDMSO OTBDMS 57 MeO 2 C CO 2 Me 40, Rh 2 (OAc) 4 PhH, reflux N O O O O H 58 acetone DMF, rt DMP, b H 2 SO 4 51 Rh 2 (OAc) 4 PhH, reflux N O O O O MeO 2 C CO 2 Me 59 a TBDMS = tert-butyldimethylsilyl b DMP = 2,2-dimethoxypropane O O OH HO HO OH Scheme 3. Initial investigations into the synthesis of 36 dihydroxyacetone would give a protected, organic-soluble analogue of 50 which would simplify isolation. Considering that TBDMS ethers 82 are more stable than TMS ethers and are easy to deprotect, first we chose TBDMSCl as protecting reagent. With DMF as solvent, imidazole as catalyst, dihydroxyacetone dimer reacted with TBDMSCl to pro- duce 55 in very high yield (92.0 %). We tried to prepare 56 from 55 by a reductive 30 amination reaction. Sodium cyanoborohydride or sodium triacetoxyborohydride was used as reducing reagent, ammonium chloride or ammonium acetate was used as amination re- agent, and a variety of reaction times and temperatures were chosen. Unfortunately, we always got an intractable mixture. We failed to produce 56 from 55, perhaps because the TBDMS group is too large. Then 2,2-dimethoxypropane was chosen as protecting reagent. According to previous work in our laboratory, dihydroxyacetone dimer 48 reacted with 2,2-dimethoxypropane (DMP) to give 53, not the desired 54 (eq. 17). 79 O OH OH 48 O O O acetone DMF, rt 53 54 [17] O O O O O O DMP a H 2 SO 4 O O OH OH HO HO a DMP = 2,2-dimethoxypropane not formed 31 Rather than protect dihydroxyacetone, we prepared 50 by the method of SKFNWABF. 78 With compound 50 in hand, we wanted to use TBDMS as a protecting group for the hydroxyls. Secondary amine 50, catalyzed by imidazole, reacted with TBDMSCl in DMF solvent to afford compound 56 in good yield (78.5 %). However, the carbenoid insertion into the N-H bond of 56 went poorly. In refluxing benzene, dimethyl diazomalonate (DDM) catalyzed by Rh 2 (OAc) 4 , reacted with protected secondary amine 56 to afford 57 in very low yield (5%). Again, the steric bulk of the TBDMS group may be a factor here. When we used DMP as protecting reagent with secondary amine 50 to afford protected secondary amine 58, the subsequent N-H insertion to form 59 went smoothly. The target 36 was obtained after 59 was reduced and the acetonide protecting groups were removed. The overall synthesis of tertiary amine 36 in five steps from dihy- droxyacetone dimer is shown in Scheme 4, and discussed in more detail in the following sections. O O OH HO OH HO N HO HO HO HO H N H O OO O NH 4 Cl NaBH 3 CN CH 3 COOH MeOH, rt N O OO O OO OMeMeO 5859 5048 N HO HO HO HO MeOH LiAlH 4, THF,rt N O OO O OH OH 60 61 36 CF 3 CO 2 - ion exchange resin H H Cl - DMP, DMF, p-TsOH, rt OMe O MeO O N 2 Rh 2 (OAc) 4 , PhH, reflux HCl + 50?HCl NH HO HO 3 N HO HO 3 + CF 3 CO 2 H H 2 O, THF rt Scheme 4. Route from dihydroxyacetone to tertiary amine 36 a) Synthesis of Acetonide 58 The first two steps of our synthesis are based on the work of SKFNWABF. 78 The first step was carried out by the method of SKFNWABF, but we modified the second step. In the second step, according to the literature method, secondary amine 50 reacted with 32 33 DMP in DMF and acetone catalyzed by concentrated sulfuric acid, then solid sodium bi- carbonate was used to neutralize the reaction solution. The solvent was removed on the rotary evaporator and the residue was partitioned between ethyl acetate and water. The aqueous layer was extracted with ethyl acetate, and the organic layer was washed with brine, dried with MgSO 4 , filtered, and concentrated to give 78% crude product 58. In our hands, the yield ranged from 30% to 70%. Also, this crude product 58 didn?t work for the next step (N-H insertion reaction). According to the paper, 78 pure 58 was obtained through the recrystallization from ether and hexane (however the yield was not reported). When we used this method to purify 58, we got a very low yield. Perhaps the following two reasons caused the yield to vary so widely: (i) solid sodium bicarbonate does not dis- solve in DMF/acetone solvent, so it is hard to completely neutralize the reaction solution. If the reaction solution cannot be totally neutralized, some protonated 58 still exists, and this protonated 58 will dissolve in the aqueous layer. Because it will not be extracted into ethyl acetate, it will lead to low yield. (ii) After removal of most of the solvent, a sticky solid was formed. The removal of the remainder of the DMF was difficult because of the high boiling point of DMF. Furthermore, the product 58 dissolves in DMF. The residual DMF will also entrain the secondary amine 58 to dissolve in the aqueous layer. In our improved method, secondary amine 50 was dissolved in methanolic HCl to form 50?HCl. Then 50?HCl was reacted with DMP in DMF, catalyzed by p-toluenesulfo- nic acid monohydrate 83 (p-TsOH). The solution was neutralized with triethylamine. The mixture was concentrated in vacuo, the residue diluted with triethylamine and ethyl ace- tate. The ammonium salts were simply filtered off, and the solvent evaporated to afford crude product 58. This crude product could be purified by column chromatography (73%) or crystallized from hexane (82%). Compared to the SKFNWABF method, we simplified the workup and improved the yield from 78% (crude yield of SKFNWABF 78 method) to 82% (purified yield of our improved method). Furthermore, we got very pure 58. This is very important for the next step: the N-H insertion reaction. b) Synthesis of tertiary amine 59 through N-H insertion reaction of rhodium(II) carbenoids The insertion of a carbene or carbenoid generated from a diazocarbonyl compound in- to an N-H bond is a very useful process which leads to C-N bond formation. Also, since the desired compound 36 has hydroxymethyl groups which can be generated by the re- duction of ester groups, dimethyl diazomalonate ("DDM") was chosen as the source of carbenoid. DDM was synthesized by a diazo transfer reaction (eq. 19). 84 [18] SO 2 N 3 NHCOCH 3 SO 2 Cl NHCOCH 3 NaN 3 CH 2 Cl 2 + SO 2 N 3 NHCOCH 3 CO 2 Me CO 2 Me CO 2 Me CO 2 Me N 2 SO 2 NH 2 NHCOCH 3 ++ Et 3 N CH 3 CN DDM (n-Bu) 4 N + Br - [19] Dirhodium tetraacetate-catalyzed insertion of DDM into the NH bond of secondary amine 58 is the key step for synthesizing hindered tertiary amine 36. However, dirhodium tetraacetate is well-known to form strong complexes with Lewis bases (including some amines), 85 which may inhibit the catalytic decomposition of DDM (Figure 2.1). In fact, Porter and his coworkers 86 found that the catalytic activity of Rh 2 (OAc) 4 was totally 34 inhibited by primary amines. This result is relevant to the N-H insertion reaction used to prepare tertiary amine 59. If the secondary amine 58 we used was impure, and included a O Rh Rh O CH 3 O O O CH 3 O O H 3 C O CH 3 B B Figure 2.1 Complex of dirhodium tetraacetate with Lewis base B little of the corresponding primary amine (i.e., the acetonide of 49), when the Rh 2 (OAc) 4 catalyst was added, the reaction solution immediately become red-brown instead of the normal green color of Rh 2 (OAc) 4 . The red-brown color of the reaction solution indicated that Rh 2 (OAc) 4 was poisoned. 87 After 10 h of refluxing in benzene, the reaction mixture showed by TLC unreacted DDM and 58 remaining. In such cases the yield of tertiary amine 59 was very low. The purity of acetonide 58 is therefore of crucial importance for this reaction. Fortunately, very pure crystalline 58 can be simply obtained by crystalliza- tion from hexane. In this key N-H insertion step, the yield was improved from 71% (us- ing 4 mole% Rh 2 (OAc) 4 ) 79 to 81% (using 2 mole% Rh 2 (OAc) 4 ). 35 Compared to acetonide 58, DDM is easy to prepare. 84a In order to attempt to drive all acetonide 58 to the desired tertiary amine 59, excess DDM was employed. However, it is very hard to convert all acetonide 58 to tertiary amine 59, even though 50% excess DDM was used. By TLC analysis, amine 58 still was present after DDM had disappeared. But the yield was improved from 81% to 84% by using a 20% excess of DDM (the yield was the same even when 50% excess DDM was used). 36 c) Reduction of diester 59 In order to reduce the ester groups of 59 to alcohols, the most commonly used rea- gents are lithium aluminum hydride (LAH) 88 and lithium borohydride. 89 According to previous work in our lab, 79 reduction of tertiary amine 59 with lithium borohydride af- forded a mixture of the fully reduced diol, the partially reduced monoalcohol, and starting material 59, which never disappeared completely even when excess lithium borohydride was used. So, we chose LAH as reducing reagent. 79,87,88a The reduction of 59 with LiAlH 4 af- forded the corresponding diol 60 at room temperature in THF under nitrogen. The yield of diol 60 was related to the ratio of diester 59 to LiAlH 4 . The 1:6 molar ratio of diester 59 to LAH was the best ratio, affording 93% isolated yield of diol 60. The yield of diol 60 could not be improved by using a larger excess of LAH; the diester 59 spot was still visible by TLC at the end of the reaction. But unreacted diester 59 is easy to recycle. The crude product was applied to a silica gel column. About 5% low-polarity starting material 59 was eluted first with hexane/EtOAc 1:3. Polar product 60 could be eluted next with ethyl acetate. The yield of diol 60 based on recovered starting material is 98%. d) Deprotection of acetonide 60 The acetonide functionality is commonly used as a protecting group for hydroxyl groups in polyhydroxylated compounds due to its stability to mildly acidic as well as ba- sic conditions. 82 As a consequence, many methods have been developed for deprotec- tion. 82,90 Basically, deprotection of acetals requires the use of protic or Lewis acids. How- ever, many of these methods suffer from disadvantages such as high acidity, long reac- tion times, inconvenient work up, unsatisfactory yields. Recently, some alternative 37 methods have been developed, including acid ion-exchange resins, 91 silica-supported sodium hydrogen sulfate as a heterogeneous catalyst, 92 and lanthanum(III)nitrate hexahydrate. 93 Acetonide 60 is a tertiary amine. At first, we thought if protic acids were employed as catalysts to deprotect the acetal groups of 60, the nitrogen would be protonated to form a salt (e.g. 61). We know that a salt like 61 would be soluble in water, and insoluble or sparingly soluble in organic solvents. So it would be challenging to purify 61 and get free tertiary amine 36. First, we tried to use insoluble acidic matrices such as silica supported sodium hydro- gen sulfate in THF, 92 or acidic ion-exchange resin (Amberlyst) in ethanol as catalysts to deprotect acetonide 60. 91 However, neither method worked for our compound 60. Pre- vious work in our lab showed HCl solution needed long reaction times. 79 Finally, trifluor- oacetic acid in aqueous THF was employed to cleave the acetal groups of 60, affording tertiary amine 36 and its trifluoroacetate salt. This mixture was applied to an ion- exchange resin column, Amberlite, IR-120, H + . The column was eluted with water first, and then a solution of 1 M aqueous ammonia. A white sticky liquid was obtained. The sticky liquid was kept on the vacuum line overnight, and it became a white solid. NMR spectra showed it was our target compound 36. 1 H and 13 C NMR spectra (in D 2 O) of compound 36 are shown in Figure 2.2. The 13 C NMR spectrum of 36 is easily assigned: According to the DEPT spectrum of 36, we knew the resonance at 61.0 ppm should be from carbon D, and 56.8 ppm peak is due to carbon E (methanol, 49.2 ppm by definition) in D 2 O. The 1 H NMR spectrum for 36 is analyzed as follows: the multiplet at 3.16 ppm is from H c . The two AB quartets at Figure 2.2 NMR spectra of compound 36 in D 2 O. Top: 400 MHz 1 H spectrum of 36 (HDO was set to 4.80 ppm). Bottom: 100 MHz 13 C spectrum (A trace of CH 3 OH is present as a chemical shift standard) 38 3.50 - 3.58 ppm are from H a and H b , which means H a and H b are magnetically non- equivalent. So H a and H b couple with each other and are also split by H c . A factor here is the chiral carbon (E) and hydrogen bonding shown below. Because of the hydrogen N OH OH O O O O H a H b H c E D 36 H H H H ? bonds, C E ? C D and C D ? O bonds cannot rotate freely, which results in H a and H b protons being more magnetically non-equivalent than in a freely rotating system. The 1 H NMR spectrum of 36 in DMSO-d 6 showed a triplet for the OH proton at 4.91 ppm. This means exchange of the OH protons was slow in this solvent, which very tentatively lends weight to the suggestion that H-bonding might be strong enough to hinder bond rotation. 2.1.3 Some properties of tertiary amine 36 In order to further prove the structure of 36, we worked very hard to get a single crystal of 36. Finally, we grew a very beautiful single crystal of 36 from THF solution. The structure of 36 as determined by X-ray crystallography is shown in Figure 2.3. For clarity, hydrogens bound to carbon have been omitted. Hydrogens bound to oxygen were located and refined during solution of the structure. From this X-ray crystal structure of 36, the distance between O 4 ---H 3 , O 2 ---H 1 is 1.80778 ?, 1.91697 ? respectively. These distances are shorter than the sum of van der Waals contact distance (2.6 ?) 113 of H???O for O-H???O hydrogen bond system. It is clear there are intramolecular hydrogen bonds (O 4 ???H 3 , O 2 ???H 1 ) in 36, just as the 1 H NMR spectrum suggested. 39 Figure 2.3 The X-ray crystal structure of compound 36. Atoms are represented as spheres of arbitrary diameter. Hydrogens bound to carbon have been omitted. More importantly, this crystal structure proves the nitrogen of 36 is essentially planar. There are two ways to quantify the planarity of nitrogen in tertiary amines. One is the sum of C-N-C angles, which will be 360? for a perfectly planar nitrogen. Another is the distance from nitrogen to the plane defined by the three carbons bound to nitrogen, which we will denote as ?h?. In tertiary amine 36, the sum of C-N-C angles is 359.05(7)?, and h is 0.082 ?. In Table 2, the h of 36 is compared to h for an ordinary trialkylamine (Et 3 N) 40 and several sterically congested trialkylamines. It is clear that 36 is one of the most planar trialkylamines known (taking the term "trialkylamine" to refer to nitrogen bound to three Table 2. h for various trialkylamines N h 0.467 ? 94 0.282 ? 94 0.140 ? 95 0.136 ? 87 0.082 ? 0.000 ? 96 Trialkyl amine N N Ph Ph Ph N HO HO N HO HO OH OH OH OH 36 N Cl Cl Cl Cl Cl Cl saturated (i.e. sp 3 ) carbons). Compound 36 is the key precursor of hypervalent nitrogen (10-N-5) for our project. As was previously discussed, oxidizing an 8-N-3 species to a 10-N-5 species includes changing the geometry of nitrogen from a pyramidal to a planar geometry, which will impose an energy cost. Now the tertiary amine 36 already has an almost planar geometry and the energy cost of changing geometry would be eliminated. So it should be a better precursor of hypervalent nitrogen species than 31. The average C(sp 3 )?N(sp 3 ) bond length among 1042 trialkylamines is 1.469 ? 0.014 ?, with the middle 50% in the range 1.460 ? 1.476 ?. 97 Remarkably, the average of the three C?N bond lengths in 36 is 1.4545(11) ?; that is, the C?N bonds of 36 are extremely short. Considering the steric crowing around nitrogen (every ?-carbon is branched), one might have predicted long C?N bonds rather than short ones. To explain this anomaly, we offer a qualitative argument based on orbital interac- tions. Consider planar 36, shown below (with CH 2 OH groups replaced by the letter A). 41 The Newman projection down an N-C bond suggests that the nitrogen p-orbital will inter- act with adjacent orbitals involved in A-C-A ?-bonding. In particular, the specific N H H A A H A A A A H A A NA 2 CH CHA 2 36 sidechain orbital shown, an antibonding 2a" orbital, is of proper symmetry for an inter- action with the p-orbital of nitrogen, also a". A more complete orbital diagram is given in Figure 2.4. The strength of the favorable N 2p ? 2a" interaction is inversely proportional to ?E. When A = CH 3 , the antibonding 2a" orbital is relatively high-lying, and the stabili- zation of the planar form by this orbital interaction is modest. However, as A becomes more electronegative, all the sidechain orbitals move to lower energy while the N 2p or- bital remains unchanged. This decreases ?E and in turn strengthens the filled-unfilled orbital interaction favoring the planar form of the amine. Having A = CH 2 OH provides significant stabilization of the planar amine. When A = Cl, the amine is absolutely planar, as noted in Table 2. The strengthening of the N 2p ? sidechain interaction along this series results in progressively shorter C-N bonds. In triisopropylamine (A = CH 3 ), the C-N bond length is 1.469(1) ? (at T = 84 K); 94 in 36 (A = CH 2 OH), it is 1.4545(11) ?; in N(CHCl 2 ) 3 (A = Cl), it is 1.418(2) ?. 96 Some interesting structural parameters of 36 from x-ray crystallography compared to various trialkylamines are shown in Table 3. 42 N H N H N H N H N 2a' 1a" a" 2a" 1a' A A A A A A A A ?E Figure 2.4. Orbital interaction diagram for an N-CHA 2 fragment Table 3. Structural parameters of 36 and various trialkylamines from X-ray crystallography h (?) Sum of C-N-C Angles (?) C-N Bond Lengths (?) a 0.082 1.4509(11), 1.4561(11), 1.4566(10) 36 NMe 3 b NEt 3 b NEt 3 d NEt 3 e N 3 b, f b, g N 3 359.05(7) 0.454 0.467 0.444 0.425 0.292 0.282 331.9 null c 335.1 336.0 348.6 349.2 1.448, 1.448, 1.448 null c 1.490, 1.517, 1.514 1.471, 1.475, 1.471 1.469(1) 1.469(1) Compound a Italics indicate an average value b reference 94 c disorder d Brady, S. F.; Singh, M. P.; Janso, J. E.; Clardy, J. Org. Lett. 2000, 2, 4047. e Born, M.; Mootz, D.; Schaefgen, S. Z. Naturforsch, Teil B 1995, 50, 101. f T = 84 K g T = 118K 43 The pK a of 36 was measured by titration of a 0.01 M aqueous solution of 36 with standard 0.01 M HCl at 25 ?C, and was found to be 3.08 ? 0.03. (We thank Dr. Yu Qin of this Department for performing this measurement). When compared with simple trialkyl- amines like triethylamine (Figure 2.5), it is clear that 36 is an unusually weak base. The diminished basicity of 36 might be due to difficulty in deforming the essentially- planar nitrogen of 36 to accommodate the additional ligand (H + ) in the conjugate acid. Examination of X?ray crystal structure of 36?HCl (Figure 2.6) lends support to this idea. (As a product of another experiment (vide infra), 36?HCl was available). N OH OHHO HO OH OH 36 N pK a = 3.08 pK a = 10.71 98a 62 N 37 pK a = 7.78 98b OH OH HO Figure 2.5. Comparison of basicities of 36 and other trialkylamines As shown in Table 4, the ammonium cation derived from 36 is severely flattened at nitrogen. Indeed it is even more deformed than the ammonium cation derived from triiso- propylamine. 94 According to Hamilton's 113 tabulation, the H???O distance is 2.6 ? in an N-H???O hy- drogen bonding system. From the X-ray crystal structure of 36?HCl, we can see the ?tri- ple? intramolecular hydrogen bond (H 1 ???O 4 , H 1 ???O 5 , H 1 ???O 6 ) in 36?HCl. It is very similar to what Holmes 114 reported in compounds 63A, 63B, and 64. The ?triple? hydrogen bonding interactions of some tertiary amine cations are summarized in Table 5. 44 Figure 2.6. The X-ray crystal structure of compound 36?HCl. Atoms are represented as spheres of arbitrary diameter. Hydrogens bound to carbon are not shown. 45 Table 4. Geometries of protonated trialkylamines Ammonium ion Average N-C length (?) Average H-N-C angle (?) Average C-N-C angle (?) Number of examples a Uncongested (CH 3 ) 3 NH + 1.48 107.5 111.4 49 (HOCH 2 CH 2 ) 3 NH + 1.50 107.0 111.8 21 Congested (acyclic) ((CH 3 ) 2 CH) 3 NH +b 1.533 105.1 113.5 1 ((HOCH 2 ) 2 CH) 3 NH +c 36?HCl 1.528 102.3 115.6 1 a Examples found in the Cambridge Crystallographic Database. b Bock, H.; G?bel, I.; Bensch, W.; Solouki, B. Chem. Ber. 1994, 127, 347-35l c This work O O P O PhPh O H N O O H H H O O P PhPh O H N O O H H H O O P PhPh O H NO OH H H 63A 63B 64 E 1/2 ox of 36 (eq. 20) was found to be 0.88 V from cyclic voltammetry on 36 (Au elec- trode, in aqueous Na 2 SO 4 , 100 mV/sec scan rate, 0 to 1.5 V, Ag/AgCl reference elec- trode). (We thank Dr. Wei Zhu of this Department for performing this measurement). This is in the same range as other hindered tertiary aliphatic amines (Figure 2.7). 87 46 tertiary anime cations 36null?Cl a 63A b 63B b 64 b d N-H (?) d O--H (?) Avg of d O--H (?) 0.90 2.22 2.26 2.18 2.22 0.91 2.40 2.26 2.24 2.3 0.91 2.21 2.18 2.50 2.30 0.91 2.37 3.29 2.17 2.27 Table 5. "Triple" hydrogen bonding interactions of some tertiary ammonium cations a This work. b see ref. 114 oxid'n red'n E 1/2 = 0.88 V (reversible) N OH OH HO HO OH OH N OH OH HO HO OH OH [20]+ e - NN 0.715 V 0.800 V 0.870 V 0.910 V N N OH OH OH OH OH OH OH OH Figure 2.7. Oxidation potentials (E 1/2 ox ) of several sterically congested trialkylamines However, in contrast to other sterically unhindered tertiary amines, the redox process for 36 was reversible. This suggests that the radical cation derived by oxidation of 36 is 47 kinetically stable. Usually, for unhindered tertiary amines, the radical cation will lose ?- H? to form the iminium cation (eq. 21 (a)), or lose ?-H + to form different products (eq. 21 (b)) according to electrochemical oxidation conditions (for example, secondary amine R 2 NH and aldehyde 115a under water) as shown below 115 (eq. 21). The C-H ? bond can N H ? R R N R R - H ? ? + NR R H ? NR R H ? ~90? ~0? HO HO + + (c) unhindered amine radical cation (d) 36 +? 21 N H ? R R - H ? + (a) (b) R R N products achieve periplanarity with the N p-orbital (i.e. dihedral angle = 0? or 180? as shown in (c)). Thus the loss of ?-H? or ?-H + is rapid and the redox process for unhindered tertiary amines is not usually reversible. However, in 36 +? , the ?-H is in the nodal plane of the p- orbital of nitrogen (dihedral angle = 90? as shown in (d)). This strongly disfavors loss of ?-H? or ?-H + and since rotating the sidechain so that the C-H ? bond is periplanar with the nitrogen p-orbital is sterically very difficult, the radical cation of 36 is relatively long- lived. Amine hexaol 36 is a highly atypical and fascinating tertiary amine. We hope it will prove to be useful in the synthesis of 41, 44, or similar systems. 48 2.2 Tris(1,3-dihydroxy-2-propyl)amine 36 incorporating some main group elements Triethanolamine reacts with a variety of main group element reagents to form the large and extensively studied class of compounds called atranes, 67 e.g. 38, 39 (eqs 22 and 23). Amine hexaol 36 may be thought of as a ?doubled? analogue of triethanolamine. So with 36 in hand, we explored a variety of reagents which might be used analogously to form compounds 40, or 41 (eqs 24 and 25). 39 (E = Si, Ge) 38 (E = B, Al, P) E N O O O E N O O O Z N OH HO HO "EX 3 " "Z-EX 3 " [22] [23] + 3 HX + 3 HX 37 41 (E = Si, Ge) 40 (E = B, Al, P) E N O O O O O O E E N O O O O O O E Z Z N OH HO HO HO OH HO 36 "EX 3 " "Z-EX 3 " [24] [25] + 6 HX + 6 HX 49 2.2.1 Reactions of 36 with various sources of boron "Double closure" of 36 to 40 or 41 is not without potential problems. Consider the reaction of 36 with "EX 3 " reagent B(OMe) 3 , for example (see Scheme 5). To reach 40 (E = B), six transesterification steps are required. Intermediate 65 is formed after the first Scheme 5 Possible pathways in the reaction of 36 with (MeO) 3 B c B OMeO O HO N OH OH OH OH N OH OH OH HO HO N B O OH OH OMe N O B O OHHO OHOH OMe N O B O HO HO OH OH OMe HO OH O N OH OHO HO OH OH b a 65 B OMeMeO 36 b c polymer 40 66 transesterification. The next transesterification may proceed either intramolecularly or intermolecularly. The latter is illustrated in Scheme 5 as path a. Further steps of this type type would eventually lead to polymeric products. Intramolecular transesterification may occur in one of two ways, shown in Scheme 5 as paths b and c. Path b could be called the "inter-sidearm" mode of cyclization, and path c the "intra-sidearm" mode of cyclization. 50 Path b is the only path which would lead to the desired product 40. Path b involves for- mation of an eight-membered ring and path c a six-membered ring, which would tend to favor path c over path b on entropic grounds. However, the B-N dative bond possible in path b (66) may provide an enthalpic driving force sufficient to favor path b over path c. If paths b and c, as well as subsequent transesterification steps, are reversible, and if the reaction is carried out under conditions of thermodynamic control, it is possible that 40 could represent the deepest thermodynamic sink and so be formed in high yield re- gardless of whether path b or c is preferred. Against the background of such considera- tions, investigations of the "double closure" of 36 were undertaken. a) The reaction of 36 with trimethyl borate, (MeO) 3 B A well-investigated method to prepare boratranes is transesterification of trialkyl- borates with tris(2-hydroxyalkyl)amines 98 (eq. 26). Normally, the reaction occurs upon B(OR') 3 + (HOCHRCH 2 ) 3 N B(OCHRCH 2 ) 3 N + 3 R'OH [26] short heating of the reagent mixture without any solvent. 99 So, the first source of boron tried with 36 was trimethyl borate. Under N 2 , the reaction proceeded on heating excess trimethyl borate and 36. Unfortunately the product didn?t dissolve in most organic sol- vents, but very easily dissolved in D 2 O. The NMR spectra are shown in Figure 2.8. The 1 H NMR spectrum was complex, but the 13 C NMR spectrum appeared much simpler. Peak A is methanol (as chemical shift standard), peak B and peak C are due to starting material 36. The other three peaks are from the product in this reaction. We tried to purify it, but it was insoluble in most common organic solvents. Our attempts to purify the product failed, so finally we gave up. 51 Figure 2.8 NMR spectra of the product of reaction of 36 with (MeO) 3 B. (a) 400 MHz 1 H NMR spectrum (b) 100 MHz 13 C NMR spectrum 52 b) The reaction of 36 and boric acid, H 3 BO 3 The simplest route to prepare boratranes is esterfication of boric acid by tris(2-hy- droxyalkyl)amines 98 (eq. 27). The second source of boron tried with 36 was boric acid. B(OH) 3 + (HOCHRCH 2 ) 3 N B(OCHRCH 2 ) 3 N + 3 H 2 O [27] A mixture of boric acid and 36 in DMF was heated under nitrogen (oil bath 130-150 ?C). A white precipitate formed after several hours. This white precipitate also didn?t dissolve in most organic solvents (CHCl 3, acetone, THF, ethyl acetate, ether, DMF, DMSO), and very easily dissolved in D 2 O (the NMR spectra were the same as in Figure 2.8). So it?s hard to determine its structure. But in an NMR tube, this white solid dissolved in DMSO- d 6 after heating for 2 - 3 h. The 1 H and 13 C spectra are shown in Figure 2.9. The mass spectrum showed molecular ions at m/e 247, and m/e 246, in the intensity ratio 5:1, as well as peaks at m/e 208, 148, and 44. The elemental analysis was (C, 43.88; H, 7.28; N, 5.55). Based on these data, this white solid may be assigned the structure 67 or 68 (cal'd for C 9 H 18 NO 6 B: C 43.76; H 7.34; N 5.67; molecular weight C 9 H 18 NO 6 11 B = 247 g/mol, C 9 H 18 NO 6 10 B = 246 g/mol). For convenience we will refer to this compound as N O HO O OH OH 67 N O O 68 OH HO HO B O BO the "one-boron" compound. Structure 67, a "triptych," implies a transannular dative bond between boron and nitrogen, and structure 68 implies none. Does the one-boron com- pound resemble triethanolamine borate (TEAB, 38 E = B), which was proved to have the 53 Figure 2.9 NMR spectra of the reaction of 36 with boric acid. (DMSO-d 6 solvent) Top: 400 MHz 1 H NMR spectrum. Bottom: 100 MHz 13 C NMR spectrum. 54 triptych structure? 100 The X-ray crystal structure, intramolecular bond distances and angles of TEAB are shown in Figure 2.10. 100c Figure 2.10. X-Ray crystal structure and some structural data for TEAB 100c 55 In order to distinguish 67 from 68, we tried to grow a crystal of the one-boron com- pound. Crystallization from DMSO/ethyl acetate (open to air for several days) gave a crystal suitable for X-ray analysis. The X-ray analysis (Figure 2.11) revealed that the one-boron compound has the triptych structure 67, and the existence of the transannular Figure 2.11 X-ray crystal structure of one-boron compound 67. Hydrogens bonded to carbon have been omitted. 56 B-N bond is confirmed by the experimental distance of 1.6875(13) ?. This is comparable with the sum of the van der Waals radii of boron and nitrogen, 3.11 ?, 101a and the sum of the covalent B-N bond, 1.58 ?. 101b The average C-N-C and B-N-C bond angles are 115.88(7)? and 101.87(7)?, respectively. All five-membered rings, e.g. N-B-O(3)-C(5)- C(8), are non-planar. Some geometric parameters of 67 and TEAB are summarized in Table 6. From the X-ray crystal structure (Figure 2.11) of one-boron 67, one may note there is no intramolecular hydrogen bonding in 67. The 1 H NMR spectrum of 67 in DMSO-d 6 showed a triplet for the OH proton at 5.025 ppm. This means exchange of the OH protons was slow in this solvent, which pro- vides evidence to the suggestion that H-bonding might be strong enough to somewhat hinder bond rotation. Table 6. Geometric parameters of 67 and TEAB Average N-C length (?) Average B-O length (?) B-N length (?) Average B-N-C angle( o ) Average C-N-C angle( o ) Average O-B-O angle( o ) Compound 67 a TEAB b 1.5093 (12) 1.4380 (13) 1.6875 (13) 1.49 1.43 1.647 (9) 114.3 104.0 114.7 (6) 115.88 (7) 101.88 (7) 114.62 (9) a This work b ref. 100c Initially, we thought the reaction of 36 with boric acid produced solely the one-boron compound 67; the two-boron compound 69 was not detected in this reaction (eq. 28). 57 + H 3 BO 3 DMF, 4-6 h 130-150 ?C [28]N O O O O O 69 B O B not formed ? N OH OH HO HO OH OH 36 N O HO O OH OH 67 B O We were interested in testing the strength of the internal B-N dative bond of 67 by reacting 67 with various nucleophiles, e.g. pyridine or triethylamine (eq. 29). + [29] ? N OHO O HO HO 67 B N N OHO O HO HO 70 B N O O We repeated the reaction of equation 28 to obtain some white solid. When we had done so several times, we were faced with results that were confusing. Sometimes the white solid product very easily dissolved in pyridine. Sometimes it was very hard to dissolve in pyridine, even after heating for several hours. We also found this white solid was very moisture sensitive (open to air just a few minutes). Eventually, we noted this white solid was very easily dissolved in pyridine before it hydrolyzed in moist air. After it was hydrolyzed, it was very hard to dissolve in pyridine. But the hydrolyzed product easily dissolved in DMSO-d 6 and the 1 H and 13 C NMR spectra were those of the one- boron compound 67 (Figure 2.9). At this point, we realized the white precipitate in equation 28 was not compound 67, but rather it was possibly the two-boron compound 69, which dissolves in pyridine. Com- pound 69 then hydrolyzes rapidly to one-boron compound 67, which does not dissolve in pyridine. To confirm this proposal, we very carefully did the reaction of equation 28 at differ- ent temperatures under nitrogen, with attention paid to the exclusion of moisture. At rt, no precipitate was formed after 36 and boric acid in DMF were stirred for one day. No re- action occurred according to the NMR spectra. The same reaction was done at 85 ? 90 ?C 58 for one day and also no white precipitate was formed. But some white solid was obtained after DMF was very carefully removed under nitrogen. This white solid did not dissolve in pyridine, but it dissolved in DMSO-d 6 . The NMR spectra were the same as 67 (Figure 2.9). However, at a reaction temperature over 130 ?C, some white precipitate was formed after approximately 4 - 6 h. This white precipitate easily dissolved in pyridine. In order to determine the molecular structure of the precipitate formed at 130 ?C, it was carefully dissolved in pyridine under nitrogen and the excess pyridine was slowly re- moved in a stream of nitrogen. A very nice crystal was formed. X-ray analysis revealed that this white crystal was 71, a complex of two-boron compound 69 with one pyridine (Figure 2.12). OO O O NB O 71 N B O Consequently, when tertiary amine 36 reacted with boric acid in DMF, at various reaction temperatures, the product could be one-boron 67 (reaction temperature below 100 ?C) or ?two-boron? 69 (reaction temperature over 100 ?C). So, equation 28 must be revised; the real product (white precipitate) is the two-boron compound 69 (eq. 30). The one-boron compound 67 dissolved in DMF, DMSO, but did not dissolve in pyridine and triethylamine. Perhaps the dative bond between nitrogen and boron in 67 is sufficiently strong that 67 doesn't react with nucleophiles such as pyridine or triethylamine. Two- boron compound 69 didn?t dissolve in most organic solvents including DMF and DMSO, however it very easily dissolved in pyridine because of reacting with pyridine to form compound 71. That means in the two-boron compound there was weaker or no dative 59 bond between nitrogen and boron compared to one-boron compound. Thus the boron of 69 has stronger electrophilicity and reacts with pyridine (a nucleophile). Both 69 and 71 are extremely moisture sensitive, hydrolyzing to give one-boron compound 67 as shown in Scheme 6. N OH OHHO HO OH OH + H 3 BO 3 DMF, 4-6 h 130 -150 ?C O O O O O 69 B N O HO O HO HO 67 B O H 2 O H 2 O [30] 36 DMF, overnight 85 - 90 ?C N OO O O NB O 71 N B O B O N Scheme 6. Reaction of 36 with H 3 BO 3 For 71, the crystal structure is shown in Figure 2.12. The unit cell contains two independent molecules, labeled A and B. The X-ray analysis revealed that 71 has a "trip- tych-and-cage" structure. Some structural parameters of 71 are shown in Table 7. The existence of the transannular (i.e. triptych) B-N bond is confirmed by the B-N distance of 1.701(4) ? (average of molecules A and B). The "cage" B????N distance is 3.093(4) ? (average of molecules A and B). The average C-N(3)-C and B-N(3)-C bond angles are 115.8(2)? and 101.99(13)?, respectively. Compared to TEAB and one-boron 67, the triptych B-N(sp 3 ) dative bond in 71 (1.701(4) ?) is longer and weaker than that of TEAB (1.647(9) ?) and 67 (1.6875(13) ?). 60 Figure 2.12. X-ray crystal structure of compound 71. There are two independent molecules in the unit cell. Atoms are represented by spheres of arbitrary diameter. All hydrogens have been omitted. Formation of two-boron compound 69 (and its hydrolysis to 67) is amazingly easy. We found the one-boron compound 67 could be prepared by mixing 36 and excess boric acid together in a mortar and grinding it for 5-10 minutes with a pestle. Excess boric acid was removed by washing with hot THF and very pure 67 was obtained in more than 98% yield. 61 Table 7. Geometric data of 71 from X-ray crystallography Average N-C length (?) B-N a length (?) Average B-N a -C angle ( ? ) Average C-N a -C angle ( ? ) Entry 71(A) c 71(B) c 1.505(3) 1.7029 3.0911 1.495(4) 1.6992 3.0958 B-N b length (?) 1.642(4) 1.645(4) 115.8(2) 101.99(13) 115.8(2) 101.93(2) a Tertiary amine nitrogen b Pyridine nitrogen c The labels A and B refer to two inde- pendent molecules in the unit cell c) Some properties of 67 1. Stability with water and nucleophilic reagents In 1960, Steinberg and Hunter 102 reported the hydrolysis rate of boratrane is 130 times as slow as that of triethylborate under neutral conditions. Such a result suggested an equilibrium between two boratrane forms with planar and tetrahedral boron configura- tion, the tetrahedral configuration having a BN bond. From the kinetic data, a hydroly- sis mechanism includes initial BN bond cleavage (equation 31). 103 N(CH 2 CH 2 OH) 3 H 3 BO 3 [31] H 2 O + B N O O O B N O O O A BN dative bond also exists in 67, according to the X-ray crystal structure of one- boron compound 67. This dative bond should stabilize 67. The following facts will prove it. NMR spectra in D 2 O demonstrated that 67 only partially hydrolyzed to tertiary amine 36 at rt and the hydrolysis ratio did not change several days later. That means 67 could 62 not be hydrolyzed completely in water at rt. And 67 was stored in a small white vial for almost 17 months under air at rt. The NMR spectra of 67 (in DMSO-d 6 ) illustrated that no 67 was hydrolyzed to tertiary amine 36. So, 67 is very stable at rt. Attack of a nucleophilic reagent at the boron atom of 67 should be slowed by the ex- istence of the BN transannular bond. This decreases the electrophilicity of the boron of 67. Perhaps, it is the reason that boratrane 67 is very hard to dissolve in pyridine and triethylamine, even after heating it. 2) Reaction of 67 with Z-Si(OC 2 H 5 ) 3 (Z = Me, Ph) In DMF, mixtures were obtained when 67 reacted with Z-Si(OC 2 H 5 ) 3 (Z = Me, Ph) at a molar ratio of 1:1. The mixtures were starting material 67, one-boron one-silicon com- pound 72 and two-silicon compound 73. But only 73 was obtained when the reaction ra- tio was 1:2. That means the siloxane is more stable than the borate for tertiary amine 36. Z-Si(OC 2 H 5 ) 3 [32]+ DMF, 4-6 h 80-150 ?C + 73 72 N O HO O OH OH 67 O O O O O SiZ Z O O O O O Si Z B O NSi O NB O d) Properties of two-boron compound 69 As discussed, two-boron compound 69 is extremely moisture sensitive and insoluble in virtually all organic solvents. It did not melt or sublime at 350-400 ?C in vacuum (2 - 5 Torr). So, it is difficult to determine its molecular structure. 63 2.2.2 Reactions of 36 with various sources of silicon a) Reactions with Z-Si(OC 2 H 5 ) 3 (Z = Ph, Me) Phenylsilatrane was first prepared by Finestone 104 through azeotropic distillation of triethanolamine and phenyl triethoxysilane with benzene (eq. 33). The same method was employed for the synthesis of silatranes by Frye and coworkers. 105 PhSi(OC 2 H 5 ) 3 + (HOCH 2 CH 2 ) 3 NPhSi(OCH 2 CH 2 ) 3 N + 3 C 2 H 5 OH [33] This method of transesterification of Si-substituted trialkoxysilanes was also used in the case of tertiary amine 36 to try to synthesize two-silicon silatranes (eq. 34). This method in DMF solution was successful in our hands in preparing two-Me two-Si com- pound 76 and two-Ph two-Si compound 75 in high yield (> 90 %). TLC was employed to follow the reactions. During these reactions, there were two new spots on TLC plates. + Z-Si(OC 2 H 5 ) 3 DMF 80 - 150 ?C 4 - 6 h O O O O O Si Z Z (Z = Ph, Me) [34] 36 N HO HO OH OH OH OH N Si O The more polar spot of the two gradually disappeared. Finally, there was only one new spot, which was identified as the two-Si compound, (either 74 or 76). The more polar spots which disappeared during the course of the reaction were regarded as intermediate one-Si compounds 75 and 77. These materials were obtained by stopping the reaction at the point at which the concentration of the polar intermediate was greatest, and 64 N O O O O O Si Ph Ph 74 N O O O O O Si Me Me N O HO O OH OH 75 N O HO O OH OH 77 Ph Me 76 Si O Si O Si O Si O performing silica gel chromatography of that reaction mixture. The 1 H and 13 C NMR spectra were consistent with the proposed structures of 75 and 77. (Figure 2.13 and 2.14) Silatranes were the first examples of atrane to be reported 105 and have been reviewed exhaustively by Voronkov. 106 The molecular structure of silatranes has been elucidated by X-ray crystal structural and conformational methods. Bond angles and lengths, includ- ing distances in silatranes (ZSi(OCH 2 CH 2 ) 3 N) could presumably range between 1.87 ? (the sum of the covalent radii of silicon and nitrogen) and 3.65 ? (the sum of the van der Waals radii of silicon and nitrogen). 107 The reported longest Si?N distance in a silatrane is in 78 (2.89(1) ?), which is 21% shorter than the sum of the van der Waals radii. 116 The shortest one is in 79 (1.965(5) ?). 117 Si N O O O Si N O O O Pt Cl PPhMe 2 Me 2 PhP 78 O Me Me BF 4 79 + ? However, in almost all of the silatranes which have been studied, the distance be- tween the silicon and nitrogen is in the range 2.0 - 2.4 ?. This distance is considerably 65 Figure 2.13 NMR spectra of compound 75. (CDCl 3 solvent) Top: 400 MHz 1 H NMR spectrum. Bottom: 100 MHz 13 C NMR spectrum. 66 Figure 2.14 NMR spectra of compound 77. (CDCl 3 solvent) Top: 400 MHz 1 H NMR spectrum. Bottom: 100 MHz 13 C NMR spectrum. 67 shorter than the sum of van der Waals radii of the silicon and nitrogen atoms. This is persuasive evidence for the existence of a transannular interaction between the silicon and nitrogen in silatranes. In silatranes ZSi(OCH 2 CH 2 ) 3 N, the Si?N dative bond length is essentially dependent on the substituent (Z) at the silicon atom (see Table 8). Thus, for example, the presence of an electron-withdrawing substituent at the silicon atom (Cl, CH 3 CH 2 O, 3-O 2 NC 6 H 4 ) should shorten the Si?N bond length. Table 8. Some structural features of silatranes ZSi(OCH 2 CH 2 ) 3 N Z Cl Me 2 O + ClCH 2 3-O 2 NC 6 H 4 Cl(CH 2 ) 3 EtO Ph(?) Et Si? N length (?) Si? Z length (?) 1.965 2.02 2.12 2.12 2.13 2.152 2.18 2.21 2.89 2.15 1.91 1.91 1.89 1.87 1.88 CH 3 2.17 1.88 2.29 1.658 1.830 Entry 1 a 2 b 3 b 4 b 5 b 6 a 7 b 8 b 9 b 10 b Average O-Si-O Angle( ) Average Z-Si-O Angle( ) Si? O length (?) 1.642 1.648 120.0 118.9 96.4 93.6 1.65 1.67 1.66 1.65 1.67 1.66 1.66 1.65 120.0 119.0 119.0 118.0 118.0 119.0 118.0 110.0 96.0 96.0 96.0 93.0 108c a ref. 117 b ref. 106 c (C 6 H 5 (CH 3 ) 2 P) 2 PtCl 68 Does a dative bond between the silicon and nitrogen exist in compounds 74 - 77? Our greatest interest is in compounds 74 and 76. The nitrogen in 74 and 76 should be consi- dered hypervalent (10-N-5) if there is a maximal transannular interaction between the silicon and nitrogen in 74 or 76. The solid-state structures of 74 and 76 will certainly of- fer unambiguous structural information. Therefore, we tried to grow crystals of 74 and 76. Recrystallization of 74 from benzene and 76 from hexane gave nice crystals suitable for X-ray analysis. The X-ray crystal structures are shown in Figure 2.15 and Figure 2.16. The results of X-ray crystallographic studies on 74 and 76 are summarized and compared to those for 1-methylsilatrane 80 and 1-phenylsilatrane 81 in Table 9. N O O CH 3 N O O Si O 80 81 Si O From Table 9, it is clear the distances between silicon and nitrogen in 74 and 76 are significantly shorter than the sum of van der Waals radii for the silicon and nitrogen at- oms, 3.65 ?. 106 This provides evidence for the existence of an attractive transannular in- teraction between silicon and nitrogen in 74 and 76. That means there exists to some ex- tent a 5c-6e bond (C???Si???N???Si???C) in 74 and 76.To the extent the 5c-6e description ap- plies, the nitrogens in 74 and 76 would be hypervalent (10-N-5). But the O-Si-O and C-Si-O angles in 74 and 76 are closer to pure tetrahedral values than the corresponding 69 Figure 2.15 X-ray crystal structure of compound 74. Atoms are represented by spheres of arbitrary diameter. All hydrogens have been omitted. 70 Figure 2.16. X-ray crystal structure of compound 76. The unit cell contains two independent molecules. Atoms are represented by spheres of arbitrary diameter. All hydrogens have been omitted. 71 Average N-C Length (?) Si-N Length (?) Compound 76(A) a 76(B) a Si-C Length (?) 2.8717 2.9736 1.829(5) 1.826(5) 2.8808 2.9607 1.829(5) 1.833(5) 81(?) e Table 9. Some interesting X-ray structural parameters of 74, 76 compared to 80, 81 Average C-Si-O Angle (?) Average O-Si-O Angle (?) Sum of C-N-C Angle (?) 1.452(6) 1.455(5) 106.8(2) 107.9(2) 107.8(3) 106.8(2) 359.9(4) 359.9(4) 112.0(2) 111.0(2) 111.1(2) 112.0(2) 80 b 1.47 2.17 1.87 93 342 118 81(?) c 81(?) d 1.46 2.19 1.88 97 345 119 1.46 1.47 2.15 2.13 1.91 1.89 97 96 342 339 118 118 a This work. The labels A and B refer to independent molecules in the unit cell b ref. 110 c ref. 111a d ref. 111b e ref. 111c 74 a 2.7662 3.0182 1.8592 1.8531 1.4652 359.0(3) 113.56(18) 111.39(18) 104.99(16) 107.47(17) angles in 80 and 81. Distances between silicon and nitrogen are longer in 74 and 76 than in 80 and 81. Perhaps this is due to the absence of a strong transannular interaction between silicon and nitrogen in 74 and 76. So, it is hard to say to what extent a transan- nular interaction exists between silicon and nitrogen in 74 and 76. b) Reaction with Si(OC 2 H 5 ) 4 In 1960, Finestone 104 tried to use transesterification to synthesize 1-ethoxysilatrane (equation 35). He failed to obtain pure 1-ethoxysilatrane due to the low melting point Si(OC 2 H 5 ) 4 + (HOCH 2 CH 2 ) 3 N C 2 H 5 OSi(OCH 2 CH 2 ) 3 N + 3C 2 H 5 OH [35] reported (35-37 ?C). However, Fry, Vogel and Hall using the same method synthesized 1-ethoxysilatrane. 105 Maybe we can also use this method to produce 82 (eq. 36). 72 Under N 2 , 36 and tetraethoxysilane were heated (oil bath below 100 ?C) in DMF so- lution. Some white solid was obtained after removal of solvent. This white solid partly dissolved in CDCl 3 . NMR spectra showed it was 82. But it was not pure and not stable. + 36 N HO HO OH OH OH OH Si(OC 2 H 5 ) 4 N O O O O O Si OC 2 H 5 OC 2 H 5 82 Si O [36] It gradually deposited a white precipitate from CDCl 3 solution. This white precipitate didn?t dissolve in any organic solvent (C 6 H 6 , CHCl 3 , THF, CH 3 OH, DMF, DMSO, ace- tone, ether) or H 2 O. We got the white precipitate directly from the reaction solution if the reaction temperature was over 130 ?C. We thought this precipitate might be the polymer 83. But the elemental analysis results demonstrate it is not the simple polymer 83. n 83 N O O O O O Si OSi O n 84 N O O O O O Si OSi O Si OH OH O m The elemental analysis results were as follows: Calculated for C 9 H 15 NSi 2 O 7 : C, 35.40; H, 4.95; N, 4.59. Found: C, 21.65; H, 4.69; N, 2.47. A copolymer like 84 (n/m = 2.5) fits the elemental analysis more closely; Calculated for 84: C, 21.59; H, 4.03; N, 2.80. Found: C, 21.65; H, 4.69; N, 2.47.) 73 c) Reaction with HSi(OC 2 H 5 ) to form 85 First we tried to use transesterification method (eq. 38) to synthesize 85. We failed to obtain 85. Instead, a white precipitate was always formed which didn?t dissolve in any organic solvent. We repeated this reaction and used CaH 2 to dry DMF. This time, no precipitate was formed. After removal of solvent, some solid was obtained. This solid easily dissolved in chloroform. NMR spectra (Figure 2.17) were consistent with 82, not 85, as the product of this reaction. + 36 N HO HO OH OH OH OH HSi(OC 2 H 5 ) 3 N O O O O O Si H H 85 Si O DMF 130 - 145 ?C [38] Voronkov and coworkers 106 thought the reactivity of the Si-H bond in trichloro-, triacetoxy- and trialkoxysilanes didn?t permit the preparation of 1-hydrosilatrane and its derivatives. Maybe this is the reason we failed to produce 85 by the method shown in equation 37. But Voronkov and coworkers 119 performed the reaction of 1-hydrosilatranes with alcohols and phenols in the presence of sodium alkoxide or phenoxide to form the corresponding 1-organoxysilatranes (eq. 38). We dried DMF by adding CaH 2 and letting it stand for two days. This DMF was used in the reaction of 36 with HSi(OEt) 3 without filtration or distillation. So, the solvent may have contained basic species (e.g. CaH 2 or Ca(OH) 2 ). A by-product of the formation of 85 is ethanol. Under basic conditions, as Voronkov found, ethanol may react with 85 to form 82. (eq. 39). 74 Figure 2.17 NMR spectra of compound 82 (CDCl 3 solvent). Top: 400 MHz 1 H NMR spectrum. Bottom: 100 MHz 13 C NMR spectrum. 75 HSi(OCHRCH 2 ) 3 N + ROH ROSi(OCHRCH 2 ) 3 N + H 2 [38] RO ? + 36 N HO HO OH OH OH OH HSi(OC 2 H 5 ) 3 N O O O O O Si H H 85 Si O [39] DMF 130 - 145 ?C N O O O O O Si OEt OEt 82 Si O CaH 2 EtOH In 1967, Zelchan and Voronkov found an interesting method for preparing difficultly accessible 1-hydrosilatranes. That was the transesterification of trialkoxysilanes with the corresponding boratranes (eq. 40). 108,109 HSi(OR') 3 + B(OCHRCH 2 ) 3 N HSi(OCHRCH 2 ) 3 N R = H, CH 3 ; R' = CH 3 , C 2 H 5 ; R'' = alkyl Al(OR'') 3 [40] The synthesis was carried out by heating a mixture of one-boron 67 and triethoxy- silane in DMF under nitrogen. A white solid was obtained after removal of the solvent. NMR spectra showed it was 85. However, does a dative bond between the silicon and nitrogen exist in compound 85? The nitrogen in 85 should be hypervalent (10-N-5) if there is a transannular interaction between the silicon and nitrogen in 85. Therefore, we tried to grow up a crystal of 85. Unfortunately, it was not successful. 2.3 Synthesis of tertiary amine 86 Tertiary amine 36 has six hydroxyl groups. It dissolves only in very polar organic solvents (DMF, DMSO) or water. Most reactions of 36 require the use of DMF as solvent. Reaction work-up is inconvenient because DMF has a high boiling point. 76 Therefore, we protected the hydroxyl groups of 36 using ClSi(CH 3 ) 3 (eq. 41). Compound 86 dissolves in many low polarity organic solvents. Compound 86 was prepared as shown in equation 41 in 82% yield. 86 N O O O O O O SiMe 3 SiMe 3 SiMe 3 Me 3 Si Me 3 Si SiMe 3 + 36 N HO HO OH OH OH OH Cl-SiMe 3 DMF [41] 77 Figure 2.18 NMR spectra of compound 85 (CDCl 3 solvent). Top: 400 MHz 1 H NMR spectrum. Bottom: 100 MHz 13 C NMR spectrum. 78 79 CONCLUSIONS 1. A very interesting precursor to a proposed hypervalent 10-N-5 species, very hindered hexaolamine 36, was imagined many years ago in our group. But many approaches for synthesizing tertiary amine 36 in our laboratory were fruitless. Fortunately, we have finally achieved the preparation of 36 with an overall yield of 49%, which was obtained in five steps by using cheap, commercially available dihydroxyacetone dimer as the starting material. 2. Some properties and structure of 36 have been studied. The pK a of 36 was found to be 3.08 ? 0.03, a low value for a tertiary amine. The X-ray crystal structure of 36 showed the nitrogen is essentially planar (sum of C-N-C angles 359.05(7) ?), and the average C-N bond length (1.454 ?) was shorter than normal. An explanation of this bond contraction is offered. The oxidation potential E 1/2 ox of 36 measured by cyclic voltammetry was found to be 0.88 V. The oxidation was reversible; oxidations of ordinary tertiary amines are usually irreversible. 3. The X-ray crystal structure of 36?HCl revealed a severely flattened tetrahedral geometry about nitrogen (average H-N-C angle 102.3 ?). That is the reason why tertiary amine 36 is an unusually weak base. 4. The reaction of 36 with boric acid is very easily led to a ?one- boron? compound, 67 which is very stable. The X-ray crystal structure of 67 showed a dative bond between 80 nitrogen and boron (1.6875(13) ?). 5. Under nitrogen, ?two-boron? compound 69 was formed in the reaction of 36 with boric acid in DMF solution. The compound 69 is very hydrolytically unstable, but the X- ray crystal structure of a complex (71) of 69 with pyridine confirmed the presence in 69 of two borons. 6. The reaction of 36 with Z-Si(OEt) 3 (Z = Me, Ph) led to analogous "one-silicon" and "two-silicon" compounds. The X-ray crystal structures of both two-silicon compounds revealed a nearly symmetrical SiNSi array (Z = Me) and an unsymmetrical one (Z = Ph). 7. The ?2H, 2Si? compound 85 was prepared by the reaction of ?one-boron? compound 67 with HSi(OEt) 3 . 8. The reaction of 36 with HSi(OEt) 3 in the basic DMF solution led to form ?2EtO, 2Si? compound 82. 81 Experimental General: DMF was dried by stirring with calcium hydride, followed by distillation under vacuum after removing calcium hydride, and then storage over calcium hydride. Benzene, THF, and toluene were distilled over sodium benzophenone ketyl under nitrogen. Acetone was dried with anhydrous calcium sulfate followed by distillation after removing calcium sulfate and storage over 4A molecular sieves. Rh 2 (OAc) 4 and other reagents used in the syntheses were purchased from the Aldrich Chemical Company and were used without further purification. Melting points were determined on a Mel-Temp ? apparatus in open capillaries and are uncorrected. The 1 H and 13 C NMR spectra were obtained on a Bruker AC-250 (operated at 250 and 62.5 MHz respectively) and Bruker Avance-400 (operated at 400 and 100 MHz respectively) spectrometers. TMS (0.00 ppm) was used as internal standard for 1 H NMR chemical shifts in all solvents except deuterium oxide, in which case, HDO was used as an internal reference (4.80 ppm). 11 B NMR was referenced to boron trifluoride etherate as 0.00 ppm. The results are reported as parts per million and coupling constant are reported in Hz. The spin multiplicities are indicated by the symbols s (singlet), d (doublet), t (triplet), q (quartet), quin (quintet), m (multiplet) and br (broad). DEPT experiments were 82 conducted at ? = 135?. A z-gradient magnitude-mode COSY microprogram was used to record COSY spectra. In 13 C NMR, chemical shifts were reported in ppm relative to the centerline of the multiplet for deuterium solvent peaks (CDCl 3 , 77.23 ppm; DMSO-d 6 , 39.51 ppm; acetone-d 6 , 29.92 ppm). For deuterium oxide, methanol was used as an internal reference (49.2 ppm). Mass spectral data were obtained using either a Finnegan 3300 or a VG 7070E mass spectrometer using a solid probe. The results are presented in terms of intensity percentage relative to the base peak. Elemental analysis was performed by Atlantic Microanalytical Lab, GA. X-ray crystallography was performed on a Bruker SMART APEX CCD X-ray diffractometer by Dr. Thomas Albrecht-Schmitt and his graduate students. Some reactions were followed by thin-layer chromatography (TLC) using pre-coated silica gel plates and visualized using a Mineralight UVGL-25 lamp, or by exposure to iodine vapor, or dipping in KMnO 4 solution. Column chromatography was performed on Sorbent Technologies silica gel (60 ?) and eluted with the indicated solvent system. Bis(1,3-dihydroxy-2-propyl)amine, 50. Sodium cyanoborohydride (10.0 g, 159 mmol) dissolved in 50 mL methanol was added dropwise to a solution of dihydroxyacetone dimer (28.7 g, 159 mmol) and ammonium chloride (2.84 g, 53.0 mmol) in a mixture of methanol (400 mL) and acetic acid (40.0 mL). After stirring for 20 to 24 h, aqueous hydrochloric acid (2.00 M, 100 mL) was added and stirring was continued for 4 h. The reaction was concentrated on a vacuum rotary evaporator. The sticky liquid residue was dissolved in methanol (100 mL), filtered and concentrated once 83 more. The viscous residue was dissolved in water and applied to an ion-exchange column (Amberlite, IR-120, H + ) prepared as described in the following paragraph. The column was eluted with water first, and then a solution of aqueous ammonia (1.00 M). The solvent was removed to give secondary amine 50, a hygroscopic sticky liquid (yield 80 - 87%). 1 H NMR (400 MHz, D 2 O) ? H : 2.98 (2 H, quin, J = 5.6, NCH), 3.58 (4 H, dd, J = 6.6, 11.8, OCH 2 ), 3.65 (4 H, dd, J = 5.6, 11.8, OCH 2 ); 13 C NMR (62 MHz, D 2 O) ? C : 57.6 (NCH), 61.3 (OCH 2 ). Preparing ion exchange column. The resin (Amberlite, IR-120, H + ) was soaked in 7% HCl solution 24 h twice (fresh HCl solution for second time). The ion exchange column was set up as an ordinary chromatography column. The column was flushed with deionized water until the eluate was neutral, at which time the column was ready for use. Bis(4,4-dimethyl-3,5-dioxanyl)amine, 58. Method A: Under nitrogen, acetone (30 mL), 2,2-dimethoxypropane (10.0 mL, 81.6 mmol) and concentrated sulfuric acid (1.00 mL) were added to a solution of 50 (1.71 g, 10.4 mmol) in DMF (10.0 mL) at room temperature. An initially formed precipitate gradually dissolved. The reaction mixture was stirred for 4 h, after which solid sodium bicarbonate (5.00 g) was added until the pH had risen to 7 (overnight). The solvent was removed on the rotary evaporator and the sticky residue was partitioned between ethyl acetate (100 mL), and water (50.0 mL). The aqueous layer was extracted with ethyl acetate (2 ? 50 mL), and organic layer was washed with brine (50 mL), dried with MgSO 4 , filtered, and concentrated. The residue was purified with column chromatography (elution solvent; hexane:ethyl acetate = 1:1 to 1:10) (yield 30-70%). 1 H NMR (400 MHz, CDCl 3 ) ? H : 1.41 (6 H, s, CCH 3 ), 1.42 (6 H, s, CCH 3 ), 2.75 (2 H, tt, J = 4.1, 6.8, NCH), 3.62 (4 H, dd, J = 6.8, 11.7, OCH 2 ), 3.93 (4 H, 84 dd, J = 4.1, 11.7, OCH 2 ). 13 C NMR (100 MHz, CDCl 3 ) ? C : 23.2, 24.7 (C(CH 3 ) 2 ), 50.0 (NCH), 64.7 (CH 2 ), 98.4 (C(CH 3 ) 2 ). Method B: Secondary amine 50 (4.00 g, 24.2 mmol) was dissolved in methanol (60 mL), 37.5% HCl solution (10 mL) was added and stirred for 2 h at rt. The solvent was removed on the rotary evaporator. The residue was dissolved in DMF (40 mL). Under nitrogen, PTSA (0.700 g, 3.60 mmol) and 2,2-dimethoxypropane (10.0 mL, 81.6 mmol) were added to the solution. The resulting clear solution was allowed to stir overnight (at least 12 h) at which time Et 3 N (0.600 mL, 4.00 mmol) was added and allowed to stir for an additional 10 min. The mixture was concentrated in vacuo and treated with Et 3 N (3.40 mL, 24.2 mmol) and EtOAc (150 mL). The precipitate was removed via filtration and the filtrate was concentrated. The residue was purified as method A to obtain 58 (4.30 g, 73.0%) or crystallized from hexane to give 82% yield. p-Acetamidobenzensulfonyl azide, 87. 112 At 0 ?C, a solution of sodium azide (16.2 g, 0.250 mol) in 50 mL water was added dropwise to a suspension of p-acetamido- benzenesulfonyl chloride (50.0 g, 0.220 mol) and tetrabutylammonium iodide (0.500 g) in 500 mL CH 2 Cl 2 . The reaction was allowed to reach rt and was stirred overnight. The organic layer was separated and washed with water (2 ? 80 mL) and brine (100 mL), dried with Na 2 SO 4 and evaporated to give pure product 87 (49.7 g, 95.7%), mp 107-109 ?C. (Lit. 112 106-108 0 C) Dimethyl diazomalonate (DDM), 51. To a stirred solution of dimethyl malonate (14.3 g, 0.110 mol) and p-acetamidobenzenesulfonyl azide (29.4 g, 0.120 mol) in acetonitrile (600 mL) at 0 ?C was added dropwise triethylamine (22.2 g, 0.220 mol). The mixture was allowed to reach rt and was stirred for 18 h. The mixture was filtered and the 85 filtrate was evaporated under reduced pressure. The residue was washed with ether/hexanes (1:1), filtered, and the solvent was evaporated. Further purification by column chromatography (hexanes/ethyl acetate = 4:1) gave light yellow liquid (15.2 g, 86.7%). 1 H NMR (250 MHz, CDCl 3 ) ? H : 3.85 (s). Dimethyl 2-(N,N-bis(4,4-dimethyl-3,5-dioxanyl)amino)malonate, 59. Under N 2 , to a solution of acetonide amine 58 (0.980 g, 4.00 mmol) in benzene (20 mL), was added 0.760 g DDM (4.80 mmol) and rhodium(II)acetate dimer (32.0 mg, 0.0700 mmol) at rt. The mixture was heated to reflux and continued for 2.0 to 2.5 h, at which time TLC showed the absence of diazo compound and acetonide amine. The solvent was removed in vacuo. The residue was purified by silica gel chromatography (EtOAc/hexane 1:3 v/v), which yielded white tertiary amine 59 (1.25 g, 83.3%). 1 H NMR (400 MHz, CDCl 3 ) ? H : 1.36, 1.40 (12H, 2s, C(CH 3 ) 2 ), 3.34 (2 H, m, 2NCH), 3.72 (4H, dd, J = 6.9, 12.0, 4 OCH), 3.77 (6H, s, OCH 3 ), 3.96 (4H, dd, OCH); 4.99 (1H, s, NCHCO). 13 C NMR (100 MHz, CDCl 3 ) ? C : 23.0, 24.3 (CCH 3 ), 51.4 (NCH), 52.6 (OCH 3 ), 63.5 (NCH 2 O), 64.3 (NCHCO), 98.2 (OCCH 3 ), 170.3 (CO). 2-(N,N-bis(4,4-dimethyl-3,5-dioxanyl)amino)-1,3-propanediol, 60. Tertiary amine 59 (0.380 g, 1.00mmol) was dissolved in THF (4 mL) and added dropwise to a suspension of LAH (0.230 g, 6.00 mmol) in THF (10 mL). The reaction was stirred overnight at room temperature and then were added sequentially water (0.230 mL), 15% sodium hydroxide (0.230 mL) and water (3 ? 0.230 mL). The mixture was filtered and the filtrate was evaporated. The residue was purified by silica gel chromatography (ethyl acetate) to give a colorless sticky liquid 60 (0.300 g, 93.0%). 1 H NMR (400 MHz, CDCl 3 ) ? H : 1.38, 1.45 (12 H, s, C(CH 3 ) 2 ), 3.15 (2 H, m, NCH), 3.27 (1 H, quint, NCH), 86 3.47 (2 H, dd, J = 7.4, 10.7, CH 2 OH), 3.59 (2 H, dd, J= 10.9, 6.05, CH 2 OH), 3.71 (4 H, dd, J = 12.0, 5.5, CH 2 O), 3.82 (4 H, dd, J = 12.0, 9.54 CH 2 O). 13 C NMR (100 MHz, CDCl 3 ) ? C : 20.4, 27.0, 49.1, 58.8, 62.3, 63.7, 97.7. Tris(1,3-dihydroxy-2-propyl)amine, 36. At 0 ?C, trifluoroacetic acid (1.00 mL) was added to a solution of 60 (1.49 g, 4.67mmol) in THF and H 2 O (25 mL, THF/H 2 O = 4:1 (v/v)). The resulting solution was allowed to warm to rt and was left overnight. Then solvent was removed in vacuo. The residue was purified on an ion exchange column (Amberlite, IR?120, H + ). The column was eluted with water first, and then a solution of aqueous ammonia (1 M). The solvent was removed to give white solid tertiary amine 7 (1.10 g, 92.0 %). mp > 190 ?C (dec.); pK a = 3.08 (T = 25 ?C, 0.01 M, titrant: 0.1 N HCl standard solution). E 1/2 = 0.88 V (rt, 0.5 M Na 2 SO 4 , in water, Au electrode); 1 H NMR (400 MHz, D 2 O) ? H : 3.16 (3 H, m, NCH), 3.54 (12 H, m, CH 2 O); 13 C NMR (100 MHz, D 2 O, methanol, 49.2) ? C : 56.8, 61.0; 1 H NMR (400 MHz, DMSO-d 6 ) ? H : 2.91 (3H, m, NCH), 3.31(12H, CH 2 O); 4.91 (6H, q, OH); 13 C NMR (100 MHz, DMSO-d 6 ) ? C : 57.1, 61.8; Anal. Calcd for C 9 H 12 NO 6 : C, 45.18; H, 8,85; N, 5.85. Found: C, 45.02; H, 8.82; N, 5.74. A crystal 0.32 mm ? 0.20 mm ? 0.39 mm was selected for X-ray crystallography with 0.71073 ? (Mo K?) radiation. Unit cell dimensions a = 10.915(2) ?, b = 8.9100(18) ?, c = 23.635(5) ?, ? = ? = ? = 90?; Z = 8. Ambient temperature, absorption coefficient = 0.114 mm -1 ; 2858 reflections were collected, 2682independent (R int = 0.0239), -14 ? h ? 14, -11 ? k ? 11, -31 ? l ? 30; Full-matrix least-squares on F 2 , data-to-parameter ratio = 16.8, Goodness-of-fit 1.026, R1 = 0.0361, wR2 = 0.1009 (I>2? (I)), R1 = 0.0378, wR2 = 87 0.1032 (all data); extinction coefficient = 0.0235(19). Complete details are given in Appendix 1. 1,3-Bis(tert-butyldimethylsilyloxy)-2-propanone, 55. At 0 ?C, tert-butyldimethyl- silyl chloride (2.11 g, 14.0 mmol) was added to a stirred solution of 1,3-dihydroxy- acetone dimer (504 mg, 2.80 mmol) and imidazole (958 mg, 14.1 mmol) in DMF (4 mL) and the mixture was stirred at rt for 7 h. It was cooled to 0 ?C, water (15 mL) was added and the reaction mixture was extracted with ether (2 ? 15 mL). The organic layer was washed with brine (25 mL), dried (Na 2 SO 4 ) and evaporated. The residue was purified by column chromatography (hexane/ethyl acetate 15:1 (v/v)) to give 55 (0.820 g, 92.0%) as a colorless oil. 1 H NMR (250 MHz, CDCl 3 ) ? H : 4.46 (4 H, s, OCH 2 ), 0.96 (18 H, s, SiC(CH 3 ) 3 ), 0.13 (12 H, s, Si(CH 3 ) 2 ); 13 C NMR (62.0 MHz, CDCl 3 ) ? C : -5.4, 18.5, 25.9, 68.0, 208.8. Bis(1,3-di-tert-butyldimethylsilyloxy-2-propyl)amine, 56. Under N 2 , at 0 ?C, TBDMSCl (1.36 g, 9.00 mmol) was added to a solution of bis(1,3-dihydroxy-2- propyl)amine 50 (0.300 g, 1.80 mmol) and imidazole (0.610 g, 9.00 mmol) in DMF (3 mL). The mixture was gradually warmed to rt and stirred for 3 ? 4 h. Workup was the same as compound 55 to give white solid compound 56 (0.880 g, 78.5%). 1 H NMR (400 MHz, CDCl 3 ) ? H : 3.57 (8 H, d, J = 5.6 Hz, OCH 2 ), 2.74 (2 H, J = 5.6 Hz, NCH), 0.89 (36 H, s, SiC(CH 3 ) 3 ), 0.03 (24 H, s, Si(CH 3 ) 2 ); 13 C NMR (100 MHz, CDCl 3 ) ? C : 63.0, 58.8, 25.9, 18.3, -5.39, -5.41. Anal. Calcd for C 30 H 71 NO 4 Si 4 : C, 57.91; H, 11.50; N, 2.25. Found: C, 58.11; H, 11.62; N, 2.23; EI?MS, m/e: 622 (M + ), 606, 564, 490, 477, 412, 330, 274, 186, 147, 71, 53. 88 56 + DDM, 57. Under N 2 , a mixture of dimethyl diazomalonate (DDM) (0.240 g, 1.50 mmol), protected secondary amine 56 (0.620 g, 1.00 mmol) and rhodium(II)acetate (15.0 mg, 0.0300 mmol) in dry benzene (10 mL) was heated (oil bath 55?60 ?C) overnight. The solvent was removed under reduced pressure. The residue was purified by column chromatography with CH 2 Cl 2 as eluent to give the title compound (0.300 g, 40.0%). 1 H NMR (250 MHz, CDCl 3 ) ? H : 4.95 (1 H, s, CHCOO), 3.68?3.86 (14 H, m, CH 2 OSi and OCH 3 ), 3.23 (2 H, m, NCH), 0.88 (36 H, s, SiC(CH 3 ) 3 ), 0.34 (24 H, s, Si(CH 3 ) 2 ); 13 C NMR (62.9 MHz, CDCl 3 ) ? C : 170.7, 64.6, 62.8, 58.9, 52.0, 25.9, 18.2, 14.1, -5.6; Anal. Calcd for C 35 H 77 NO 8 Si 4 : C, 55.88; H, 10.32; N, 1.86; Found: C, 56.11; H, 10.38; N, 1.89. EI-MS, m/e: 751(M-1), 736, 692, 662, 606, 462, 404, 330, 316, 253. 2,8,9-Tris(hydroxymethyl)-5-bora-1-aza-4,6,11-trioxatricyclo[3.3.3.0 1,5 ]- undecane, ("one-boron compound"), 67. Method A: Under nitrogen, the mixture of tertiary amine 36 (100 mg, 0.420 mmol) and H 3 BO 3 (25.8 mg, 0.420 mmol) in DMF (3.00 mL) was heated (oil bath 165?175 ?C) for 3 - 5 h. Solvent was removed in a gentle stream of N 2 providing white solid product. The product was further purified by washed with hot THF and then keeping on the vacuum line for 2 days to give the title compound 67 (101 mg, 97.0%) mp: 222?223.5 ?C. 1 H NMR (400 MHz, DMSO?d 6 ) ? H : 4.50 (3 H, t, OH), 3.73-3.79 (6 H, m, CH 2 ), 3.57 (3 H, q, CH 2 ), 3.44 (3 H, t, CH 2 ), 3.31-3.37 (3 H, m, CH). 13 C NMR (100 MHz, DMSO-d 6 ) ? C : 64.2, 62.0, 57.2; Anal. Calcd for C 9 H 18 NO 6 B: C, 43.73; H, 7.37; N, 5.67. Found: C, 43.88; H, 7.28; N, 5.55. EI-MS, m/e: 247 (M + ), 246, 208, 148, 44. A crystal 0.156 mm ? 0.160 mm ? 1.540 mm was selected for X-ray crystallography with 0.71073 ? (Mo K?) radiation: monoclinic a = 16.9503(11) ?, b = 16.9503(11) ?, c = 14.8701(10) ?, ? = ? = ? = 90.00?; Z = 16, 2651 reflections were 89 collected, 2615 independent, -22 ? h ? 22, -22 ? k ? 22, -19 ? l ? 19.The structure was solved by direct methods with refinement by full-matrix least squares on F 2 , Goodness- of-fit 1.056, resulting in final R indices of R1 = 0.0316, wR2 = 0.0804 (I > 2? (I)), R1 = 0.0319, wR2 = 0.0807 (all data). Full details are given in Appendix 2. Method B: Tertiary amine 36 (0.478 g, 2.00 mmol) and H 3 BO 3 (0.310 g, 5.00 mmol) were mixed together and ground thoroughly with a mortar and pestle. First the mixture became wet, and grinding was continued until it became very dry. THF (60 mL) was added and refluxed for 2 h. The mixture was filtered (hot) to give white solid product 67 (0.482 g, 97.6%). Reaction of 67 with pyridine. Under N 2 , at rt, the mixture of compound 67 (50.0 mg) and pyridine (3.00 mL) was stirred overnight. Compound 67 didn?t dissolve in pyridine. Then the mixture was heated to reflux for 3-4 h. The solid still didn?t dissolve in pyridine. After filtration, the solvent was removed to give some white solid. NMR showed it still was compound 67. So 1-B compound didn?t react with pyridine. 1,7-Dibora-11-aza-2,6,8,14,15,17-hexaoxatetracyclo[8.4.2.2. 7,12 0 4,11 ]octadecane, ("two-boron compound"), 69. Under N 2 , the solution of tertiary amine 36 (200 mg, 0.840 mmol) and boric acid (104 mg, 1.68 mmol) in DMF (10 mL) was heated (oil bath 145 ? 155 ?C) for 4-6 h (A stream of nitrogen was used to carefully to blow off some water drops which formed on flask neck). After 3 h heating, some solid was formed. The solvent was removed (the best way is to use nitrogen to blow off DMF) to give white solid (234 mg). It does not dissolve in most organic solvents and is very moisture sensitive, hydrolyzing to the one-boron compound, mp > 260 ?C. 90 Two-boron?pyridine compound, 71. Method A: Under N 2 , compound 69 (60.0 mg) was added to pyridine (2.50 mL). At rt, stirred for 4 - 5 h and then the solvent was slowly blown off by nitrogen to give white crystalline compound 71 (85.1 mg, 87.5%) This white crystal is very moisture-sensitive, hydrolyzing to 67. 1 H NMR (400 MHz, CDCl 3 ) ? H : 8.79 (2 H, dd, pyridine), 8.08 (1 H, tt, pyridine), 7.64 (2 H, m, pyridine), 4.15 (3 H, m, CH 2 ), 3.95 (3 H, m, CH 2 ), 3.62-3.75 (9 H, m, CH 2, CH). 13 C NMR (100 MHz, CDCl 3 ) ? C : 143.9, 141.7, 125.5, 63.9, 63.6, 57.3; mp > 40 ?C (dec.). A crystal 0.34 ? 0.16 ? 0.16 mm was selected for X-ray crystallography with 0.71073 ? radiation: monoclinic a = 11.5031(8) ?, b = 11.6639(8) ?, c = 12.9997(9) ?, ? = 97.56(3)?, ? = 92.13(3)?, ? = 117.95(3)?; Z = 4; 7490 reflections were collected, 4658 independent, -15 ? h ? 15, -15 ? k ? 15, -17 ? l ? 17. Full-matrix least- squares refinement on F 2 , data-to-parameter ratio = 17.3, Goodness-of-fit = 1.092, R1 = 0.0762, wR2 = 0.2046 (I > 2? (I)), R1 = 0.1132, wR2 = 0.2235 (all data). The structure revealed the compound had crystallized as a pyridine adduct. Full details are given in Appendix 3. Method B: Under N 2 , a solution of tertiary amine 36 (100 mg, 0.420 mmol) and pyr?BH 3 (0.11 mL, 0.84 mmol, 8 M) in DMF was stirred overnight at rt. The solvent was slowly blown off by nitrogen to give white crystal 2 B?pyridine 71(154 mg, 89 %) directly. 2Ph?2Si compound, 74. Phenyl triethoxysilane (0.606 mL, 2.52 mmol) was added to the solution of tertiary amine 36 (100 mg, 0.420 mmol) in DMF (2.50 mL). Under N 2 , the solution was heated (oil bath 135-145 ?C) for 4-6 h (or TLC may be used to follow the reaction). The solvent was removed under reduced pressure and the residue was purified 91 by recrystallization from xylene to afford white solid compound 74 (159 mg, 84%). 1 H NMR (400 MHz, CDCl 3 ) ? H : 7.69 (4 H, m, Ph), 7.39 (6 H, m, Ph), 3.81 (6 H, dd, CH 2 ), 3.74 (6 H, t, CH 2 ), 3.50 (3 H, m, CH); 13 C NMR (100 MHz, CDCl 3 ) ? C : 134.3, 131.9, 130.5, 128.0, 61.1, 57.6; Anal. Calcd for C 21 H 25 NSi 2 O 6 : C, 56.86; H, 5.68; N, 3.16. Found: C, 56.90; H, 5.85; N, 3.17. A crystal 0.325 mm ? 0.290 mm ? 0.280 mm was selected for X-ray crystallography with 0.71073 ? (Mo K?) radiation: monoclinic, a = 10.483(2) ?, b = 11.489(2) ?, c = 17.440(4) ?, ? = 90.00?, ? = 101.86(3)?, ? = 90.00?; Z = 4; 4672 reflections were collected, 3223 independent, -13 ? h ? 13, -15 ? k ? 15, -23 ? l ? 22. Full-matrix least-squares refinement on F 2 , data-to-parameter ratio = 17.2, Goodness-of-fit = 1.819, R1 = 0.1253, wR2 = 0.2892 (all data), R1 = 0.0977, wR2 = 0.2747 (I > 2?(I)). The complete details are given in Appendix 4. "One-phenyl-one-silicon" (1Ph-1Si) compound, 75. The solution of tertiary amine 36 (200 mg, 0.820 mmol) and phenyl triethoxysilane (0.820 mL, 3.36 mmol) in DMF (5 mL) was heated (oil bath 130-145 ?C). TLC was used to follow the reaction. The reaction was stopped immediately when the spot of 1Ph-1Si 75 was detected (acetone solvent, KMnO 4 as visualization reagent) on TLC plate. The solvent was removed under reduced pressure and the residue was purified by column chromatography with ethyl acetate and acetone as eluent to give 2Ph?2Si 74 (40 mg) and 1Ph?1Si (148 mg, 40%). 1 H NMR (400 HMz, CDCl 3 ) ? H : 7.69 (2 H, m, Ph), 7.34 (3 H, m, Ph), 4.18 (3 H, br, OH), 3.58-3.78 (12 H, m, CH 2 ), 3.42 (3 H, m, CH). 13 C NMR (100 MHz, CDCl 3 ) ? C : 134.3, 134.2, 129.9, 127.9, 61.8, 61.1, 57.0; Anal. Calcd for C 15 H 23 NSiO 6 : C, 52.77; H, 6.79; N, 4.10; Found: C, 52.39; H, 6.83; N, 4.08. 92 "Two-methyl-two-silicon" (2Me-2Si) compound, 76. Tertiary amine 36 (100 mg, 0.420 mmol) was added to a solution of methyl triethoxysilane (0.500 mL) and DMF (2.50 mL). The mixture was heated (oil bath 95-120 ?C) for 7-9 h until TLC indicated no starting tertiary amine 36. The solvent was removed under reduced pressure to afford white solid compound 76 (122 mg, 91.0%). This was further purified by recrystallization with hexanes, mp > 325 ?C. 1 H NMR (400 MHz, CDCl 3 ) ? H : 3.63 (6 H, dd, CH 2 ), 3.55 (6 H, t, CH 2 ), 3.29 (3 H, m, CH). 13 C NMR (100 MHz, CDCl 3 ) ? C : 60.8, 57.2, -4.9; Anal. Calcd for C 11 H 21 NSiO 6 : C, 41.36; H, 6.63; N, 4.38. Found: C, 41.51; H, 6.71; N, 4.39; EI-MS, m/e, 319 (M + ), 298, 284, 257. A crystal 0.183 mm ? 0.138 mm ? 0.113 mm was selected for X-ray crystallography with 0.71073 ? (Mo K?) radiation: monoclinic, a = 10.2030(6) ?, b = 11.1393(7) ?, c = 26.179(2) ?, ? = 90.0000(10)?, ? = 98.2610(10)?, ? = 90.0000(10)?; Z = 8; 7280 reflections were collected, 4542 independent, -13 ? h ? 13, - 14 ? k ? 14, -34 ? l ? 34. Full-matrix least-squares refinement on F 2 , data-to-parameter ratio = 17.2, Goodness-of-fit = 1.053, R1 = 0.1389, wR2 = 0.3176 (all data), R1 = 0.1010, wR2 = 0.2919 (I > 2?(I)). The complete details are given in Appendix 5. One-methyl-one-silicon (1Me-1Si) compound, 77. The solution of tertiary amine 36 (200 mg, 0.840 mmol) and MeSi(OEt) 3 (0.680 mL, 3.40 mmol) in DMF (6 mL) was heated (oil bath 120-135 ?C). The reaction was followed by TLC. After 4 h, the spot of 2Me-2Si 76 compound was detected on the TLC plate. The solvent was removed under reduced pressure to give some sticky residue. This residue was purified as follows: hexanes (55 mL) was added to the residue and refluxed for 5-10 minutes, filtered (hot), filtrate was evaporated to give 2Me-2Si 76 (87 mg). The solid (insoluble in hexanes) was 93 purified by column chromatography to give 1Me?1Si 77 (89 mg, 39%) and tertiary amine 36 (60 mg) (acetone and methanol as solvent). 1 H NMR (400 MHz, CDCl 3 ) ? H : 4.69 (3 H, br, OH), 3.51-3.67 (12 H, m, CH 2 ), 3.34 (3 H, m, CH), 0.10 (3 H, s, CH 3 ); 13 C NMR (100 MHz, CDCl 3 ) ? C : 61.6, 60.9, 57.0, -4.5; Anal. Calcd for C 10 H 21 NSiO 6 : C, 42.99; H, 7.58; N, 5.01; Found: C, 42.91; H, 7.39; N, 5.58. Attempts to synthesize two-hydrogen-two-silicon compound 85. Method A: Under nitrogen, the solution of tertiary amine 36 (100 mg, 0.420 mmol) and triethoxysilane (154 ?L, 0.840 mmol) in DMF (3 mL) was heated (oil bath 110-130 ?C) for 6-8 h, at which time TLC (ethyl acetate as solvent) indicated no tertiary amine remained and also some white solid was formed. The reaction was halted, the solvent was removed under reduced pressure to give a white solid. This solid was washed DMF, benzene, acetone and then put on vacuum for 4 days to give white solid (120 mg). It didn?t dissolve in any solvent (H 2 O, DMF, DMSO, alcohols, CHCl 3 , acetone, acetonitrile, ethyl acetate, trifluoroacetic acid). Method B: Under N 2 , the solution of 67 compound (100 mg, 0.410 mmol) and triethoxysilane (149 ?L, 0.820 mmol) in DMF (3 mL) was heated (oil bath 80-110 ?C). The reaction was followed by TLC. After about 4 h, no 67 compound was detected on TLC plate. The solvent was removed under reduced pressure to give white solid. This solid was dissolved in xylene, filtered and the xylene was removed to give 2H?2Si 85 (102 mg). 1 H NMR (400 MHz, CDCl 3 ) ? H : 4.22 (2 H, s, HSi), 3.69 (6 H, dd, CH 2 ), 3.58 (6 H, t, CH 2 ), 3.34 ( 3 H, tt, CH). 13 C NMR (100 MHz, CDCl 3 ) ? C : 60.5, 57.4. Reaction of tertiary amine 36 with tetraethoxysilane. Under N 2 , the solution of tertiary amine 36 (100 mg, 0.420 mmol) and tetraethoxysilane (0.500 ml, 2.24 mmol) in 94 DMF (3 mL) was heated (oil bath 135-145 ?C) overnight. Some white precipitate was formed. The precipitate was filtered and filter cake was washed with water, benzene and acetone to give white solid 0.1 g. This white solid didn?t dissolved in any solvent. The elemental analysis results were: C, 21.65; H, 4.69; N, 2.47. Reaction of tertiary amine 36 with SiCl 4 . The solution of tertiary amine 36 (100 mg, 0.420 mmol) in DMF (3 mL) was cooled to -5 ?C, then silicon tetrachloride (96.5 ?L, 0.840 mmol) was added dropwise. The reaction mixture was warmed gradually to room temperature and an initially formed precipitate dissolved. The reaction was stirred for 4 h at rt (after 1.5 h, the solution became cloudy and some precipitate was formed again). The reaction mixture was filtered to give 120 mg of a white solid. This was dissolved in H 2 O (15 mL) and filtered. The filtrate was concentrated under reduced pressure to give white solid (91.7 mg). This was recrystallized from methanol to give white crystal. 1 H NMR (400 MHz, D 2 O) ? H : 3.99 (1 H, m, CH; 2 H, m, CH 2 ), 3.90 (2 H, q, CH 2 ), 2.68 (2 H, t, OH); 13 C NMR (100 MHz, D 2 O) ? C ; 63.5, 57.6. The X-ray crystal structure showed it was tertiary amine HCl salt 36?HCl. A crystal 0.278 mm x 0.165 mm x 0.280 mm was selected for X-ray crystallography with 0.71073 ? (Mo K?) radiation: monoclinic a = 6.8972(4) ?, b = 8.2335(5) ?, c = 11.2422(7) ?, ? = 92.2850(10)?, ? = 102.8470(10)?, ? = 91.2820(10)?; Z = 2; 3019 reflections were collected, 2805 independent, -9 ? h ? 9, -10 ? k ? 10, -14 ? l ? 14. Full-matrix least-squares refinement on F 2 , data-to-parameter ratio = 12.4, Goodness-of-fit = 1.068, R1 = 0.0313, wR2 = 0.0842 (all data), R1 = 0.0297, wR2 = 0.0831 (I > 2? (I)). Full details are given in Appendix 6. 95 Protected tertiary amine, 86. At 0 ?C, trimethylsilyl chloride (0.480 mL, 3.78 mmol) was added to a stirred solution of tertiary amine 36 (100 mg, 0.420 mmol) and imidazole (260 mg, 3.78 mmol) in DMF (10 mL). The mixture was stirred at 0 ?C for 1 h and stirred for 4 h at rt. Water (20 mL) was added to the reaction solution at 0 ?C. The reaction mixture was extracted with ether (3 ? 20 mL) and the organic layer was washed with brine (2 ? 15 mL), dried with sodium sulfate and evaporated. The residue was purified by column chromatography on silica gel using hexane:ethyl acetate (20:1) as the eluent to give 230 mg (82%) of compound 86 as a colorless oil. 1 H NMR (400 MHz, CDCl 3 ) ? H : 3.60 (12 H, d, CH 2 ), 3.06 (3 H, m, CH), 0.15 (54 H, s, CH 3 ); 13 C NMR (100 MHz, CDCl 3 ) ? C : 62.9, 58.1, -0.3; Anal. Cacld for C 27 H 69 NO 6 Si 6 : C, 48.23; H, 10.34; N, 2.08; Found: C, 48.51; H 10.56; N, 2.21. Reaction of tertiary amine 36 with aluminum isopropoxide. This reaction was tried several times under the following conditions (in all reactions the molar ratio of tertiary amine 36 and aluminum isopropoxide was 1:2): (a) benzene as solvent, the mixture was refluxed for 6-8 h. (b) DMF as solvent, the mixture was heated (oil bath 125- 135 ?C) for 6-8 h. (c) 1:1 benzene and DMF (v/v) as solvent, the solution was stirred overnight at rt. Under these conditions, all gave a white precipitate, mp> 260 0 C. 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APPENDICES 107 APPENDIX 1 CRYSTAL STRUCTURE DATA FOR COMPOUND 36 108 data_pbca (tertiary amine) _audit_creation_method SHELXL-97 _chemical_name_systematic _chemical_name_common ? _chemical_melting_point ? _chemical_formula_moiety ? _chemical_formula_sum 'C9 H15 N O6' _chemical_formula_weight 233.22 loop_ _atom_type_symbol _atom_type_description _atom_type_scat_dispersion_real _atom_type_scat_dispersion_imag _atom_type_scat_source 'C' 'C' 0.0033 0.0016 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'H' 'H' 0.0000 0.0000 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'N' 'N' 0.0061 0.0033 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'O' 'O' 0.0106 0.0060 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' _symmetry_cell_setting ? _symmetry_space_group_name_H-M ? loop_ _symmetry_equiv_pos_as_xyz 'x, y, z' '-x+1/2, -y, z+1/2' '-x, y+1/2, -z+1/2' 'x+1/2, -y+1/2, -z' '-x, -y, -z' 'x-1/2, y, -z-1/2' 'x, -y-1/2, z-1/2' '-x-1/2, y-1/2, z' _cell_length_a 10.915(2) _cell_length_b 8.9100(18) _cell_length_c 23.635(5) _cell_angle_alpha 90.00 _cell_angle_beta 90.00 _cell_angle_gamma 90.00 _cell_volume 2298.6(8) _cell_formula_units_Z 8 _cell_measurement_temperature 193(2) _cell_measurement_reflns_used ? 109 _cell_measurement_theta_min ? _cell_measurement_theta_max ? _exptl_crystal_description ? _exptl_crystal_colour ? _exptl_crystal_size_max 0.39 _exptl_crystal_size_mid 0.32 _exptl_crystal_size_min 0.20 _exptl_crystal_density_meas ? _exptl_crystal_density_diffrn 1.348 _exptl_crystal_density_method 'not measured' _exptl_crystal_F_000 992 _exptl_absorpt_coefficient_mu 0.114 _exptl_absorpt_correction_type ? _exptl_absorpt_correction_T_min ? _exptl_absorpt_correction_T_max ? _exptl_absorpt_process_details ? _exptl_special_details ; ? ; _diffrn_ambient_temperature 193(2) _diffrn_radiation_wavelength 0.71073 _diffrn_radiation_type MoK\a _diffrn_radiation_source 'fine-focus sealed tube' _diffrn_radiation_monochromator graphite _diffrn_measurement_device_type ? _diffrn_measurement_method ? _diffrn_detector_area_resol_mean ? _diffrn_standards_number ? _diffrn_standards_interval_count ? _diffrn_standards_interval_time ? _diffrn_standards_decay_% ? _diffrn_reflns_number 21931 _diffrn_reflns_av_R_equivalents 0.0239 _diffrn_reflns_av_sigmaI/netI 0.0136 _diffrn_reflns_limit_h_min -14 _diffrn_reflns_limit_h_max 14 _diffrn_reflns_limit_k_min -11 _diffrn_reflns_limit_k_max 11 _diffrn_reflns_limit_l_min -31 _diffrn_reflns_limit_l_max 30 _diffrn_reflns_theta_min 1.72 _diffrn_reflns_theta_max 28.32 _reflns_number_total 2858 _reflns_number_gt 2682 _reflns_threshold_expression >2sigma(I) _computing_data_collection ? _computing_cell_refinement ? 110 _computing_data_reduction ? _computing_structure_solution 'SHELXS-97 (Sheldrick, 1990)' _computing_structure_refinement 'SHELXL-97 (Sheldrick, 1997)' _computing_molecular_graphics ? _computing_publication_material ? _refine_special_details ; Refinement of F^2^ against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F^2^, conventional R-factors R are based on F, with F set to zero for negative F^2^. The threshold expression of F^2^ > 2sigma(F^2^) is used only for calculating R- factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F^2^ are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. ; _refine_ls_structure_factor_coef Fsqd _refine_ls_matrix_type full _refine_ls_weighting_scheme calc _refine_ls_weighting_details 'calc w=1/[\s^2^(Fo^2^)+(0.0650P)^2^+0.5358P] where P=(Fo^2^+2Fc^2^)/3' _atom_sites_solution_primary direct _atom_sites_solution_secondary difmap _atom_sites_solution_hydrogens geom _refine_ls_hydrogen_treatment mixed _refine_ls_extinction_method SHELXL _refine_ls_extinction_coef 0.0235(19) _refine_ls_extinction_expression 'Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^' _refine_ls_number_reflns 2858 _refine_ls_number_parameters 170 _refine_ls_number_restraints 0 _refine_ls_R_factor_all 0.0378 _refine_ls_R_factor_gt 0.0361 _refine_ls_wR_factor_ref 0.1032 _refine_ls_wR_factor_gt 0.1009 _refine_ls_goodness_of_fit_ref 1.026 _refine_ls_restrained_S_all 1.026 _refine_ls_shift/su_max 0.001 _refine_ls_shift/su_mean 0.000 loop_ 111 _atom_site_label _atom_site_type_symbol _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_U_iso_or_equiv _atom_site_adp_type _atom_site_occupancy _atom_site_symmetry_multiplicity _atom_site_calc_flag _atom_site_refinement_flags _atom_site_disorder_assembly _atom_site_disorder_group O3 O 0.54781(7) 0.02502(8) 0.29744(3) 0.02818(18) Uani 1 1 d . . . N1 N 0.54025(7) 0.31619(9) 0.37092(3) 0.01954(18) Uani 1 1 d . . . O5 O 0.79707(6) 0.22275(9) 0.46848(3) 0.02734(18) Uani 1 1 d . . . O2 O 0.70558(7) 0.47638(8) 0.29885(3) 0.03115(19) Uani 1 1 d . . . O6 O 0.23938(7) 0.41860(9) 0.43489(3) 0.0320(2) Uani 1 1 d . . . O1 O 0.57161(7) 0.63151(9) 0.37812(3) 0.03117(19) Uani 1 1 d . . . O4 O 0.49101(7) -0.00440(8) 0.40596(3) 0.03160(19) Uani 1 1 d . . . C9 C 0.70469(8) 0.31217(10) 0.44233(4) 0.0238(2) Uani 1 1 d . . . H9A H 0.7443 0.3895 0.4185 0.029 Uiso 1 1 calc R . . H9B H 0.6570 0.3644 0.4720 0.029 Uiso 1 1 calc R . . C8 C 0.54598(8) 0.10566(10) 0.44156(4) 0.0224(2) Uani 1 1 d . . . H8A H 0.6024 0.0563 0.4686 0.027 Uiso 1 1 calc R . . H8B H 0.4818 0.1583 0.4635 0.027 Uiso 1 1 calc R . . C7 C 0.44848(8) 0.40750(10) 0.39898(4) 0.02057(19) Uani 1 1 d . . . H7A H 0.4702 0.4086 0.4401 0.025 Uiso 1 1 calc R . . C6 C 0.61682(7) 0.21878(9) 0.40556(3) 0.01820(18) Uani 1 1 d . . . H6A H 0.6689 0.1593 0.3789 0.022 Uiso 1 1 calc R . . C5 C 0.53957(8) 0.30275(10) 0.30952(4) 0.02108(19) Uani 1 1 d . . . H5A H 0.4875 0.3874 0.2956 0.025 Uiso 1 1 calc R . . C4 C 0.66648(9) 0.32921(11) 0.28415(4) 0.0246(2) Uani 1 1 d . . . H4A H 0.7251 0.2542 0.2991 0.030 Uiso 1 1 calc R . . H4B H 0.6631 0.3187 0.2425 0.030 Uiso 1 1 calc R . . C3 C 0.31751(8) 0.34618(11) 0.39490(4) 0.0253(2) Uani 1 1 d . . . H3A H 0.2855 0.3627 0.3562 0.030 Uiso 1 1 calc R . . H3B H 0.3181 0.2368 0.4022 0.030 Uiso 1 1 calc R . . 112 C2 C 0.45118(9) 0.57150(11) 0.37894(4) 0.0267(2) Uani 1 1 d . . . H2A H 0.4159 0.5775 0.3404 0.032 Uiso 1 1 calc R . . H2B H 0.3995 0.6330 0.4044 0.032 Uiso 1 1 calc R . . C1 C 0.48189(9) 0.16001(11) 0.28532(4) 0.0263(2) Uani 1 1 d . . . H1A H 0.3978 0.1502 0.3006 0.032 Uiso 1 1 calc R . . H1B H 0.4752 0.1710 0.2438 0.032 Uiso 1 1 calc R . . H1 H 0.6136(15) 0.5766(18) 0.3567(6) 0.043(4) Uiso 1 1 d . . . H2 H 0.7841(16) 0.4846(17) 0.2956(7) 0.044(4) Uiso 1 1 d . . . H3 H 0.5303(14) 0.0024(16) 0.3317(7) 0.039(4) Uiso 1 1 d . . . H4 H 0.4234(16) -0.0281(18) 0.4183(7) 0.047(4) Uiso 1 1 d . . . H5 H 0.8444(16) 0.1926(17) 0.4418(7) 0.048(4) Uiso 1 1 d . . . H6 H 0.2589(17) 0.3829(19) 0.4660(8) 0.055(4) Uiso 1 1 d . . . loop_ _atom_site_aniso_label _atom_site_aniso_U_11 _atom_site_aniso_U_22 _atom_site_aniso_U_33 _atom_site_aniso_U_23 _atom_site_aniso_U_13 _atom_site_aniso_U_12 O3 0.0274(4) 0.0288(4) 0.0284(4) -0.0075(3) -0.0001(3) - 0.0008(3) N1 0.0184(3) 0.0241(4) 0.0162(3) -0.0003(3) -0.0005(2) 0.0048(3) O5 0.0211(3) 0.0373(4) 0.0237(3) 0.0024(3) -0.0056(2) 0.0018(3) O2 0.0240(4) 0.0257(4) 0.0437(4) 0.0003(3) 0.0061(3) - 0.0019(3) O6 0.0219(3) 0.0467(5) 0.0275(4) 0.0037(3) 0.0055(3) 0.0099(3) O1 0.0267(4) 0.0252(4) 0.0416(4) -0.0062(3) 0.0022(3) - 0.0024(3) O4 0.0305(4) 0.0321(4) 0.0321(4) -0.0050(3) 0.0046(3) - 0.0139(3) C9 0.0216(4) 0.0242(4) 0.0255(4) -0.0015(3) -0.0062(3) - 0.0006(3) C8 0.0217(4) 0.0237(4) 0.0220(4) 0.0014(3) -0.0003(3) - 0.0030(3) C7 0.0174(4) 0.0239(4) 0.0204(4) -0.0016(3) 0.0002(3) 0.0029(3) C6 0.0162(4) 0.0199(4) 0.0185(4) 0.0002(3) -0.0013(3) 0.0000(3) 113 C5 0.0199(4) 0.0255(4) 0.0178(4) -0.0007(3) -0.0012(3) 0.0012(3) C4 0.0247(4) 0.0270(4) 0.0222(4) 0.0001(3) 0.0040(3) - 0.0003(3) C3 0.0174(4) 0.0327(5) 0.0257(4) -0.0004(4) 0.0016(3) 0.0010(3) C2 0.0222(4) 0.0248(4) 0.0329(5) -0.0006(4) 0.0001(3) 0.0035(3) C1 0.0217(4) 0.0333(5) 0.0239(4) -0.0068(4) -0.0037(3) - 0.0005(4) _geom_special_details ; All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. ; loop_ _geom_bond_atom_site_label_1 _geom_bond_atom_site_label_2 _geom_bond_distance _geom_bond_site_symmetry_2 _geom_bond_publ_flag O3 C1 1.4306(13) . ? O3 H3 0.855(17) . ? N1 C7 1.4509(11) . ? N1 C5 1.4561(11) . ? N1 C6 1.4566(10) . ? O5 C9 1.4262(11) . ? O5 H5 0.858(18) . ? O2 C4 1.4221(12) . ? O2 H2 0.864(18) . ? O6 C3 1.4273(11) . ? O6 H6 0.829(18) . ? O1 C2 1.4192(12) . ? O1 H1 0.839(16) . ? O4 C8 1.4247(11) . ? O4 H4 0.821(18) . ? C9 C6 1.5387(12) . ? C9 H9A 0.9900 . ? C9 H9B 0.9900 . ? C8 C6 1.5290(12) . ? 114 C8 H8A 0.9900 . ? C8 H8B 0.9900 . ? C7 C3 1.5335(12) . ? C7 C2 1.5364(14) . ? C7 H7A 1.0000 . ? C6 H6A 1.0000 . ? C5 C4 1.5278(13) . ? C5 C1 1.5301(13) . ? C5 H5A 1.0000 . ? C4 H4A 0.9900 . ? C4 H4B 0.9900 . ? C3 H3A 0.9900 . ? C3 H3B 0.9900 . ? C2 H2A 0.9900 . ? C2 H2B 0.9900 . ? C1 H1A 0.9900 . ? C1 H1B 0.9900 . ? loop_ _geom_angle_atom_site_label_1 _geom_angle_atom_site_label_2 _geom_angle_atom_site_label_3 _geom_angle _geom_angle_site_symmetry_1 _geom_angle_site_symmetry_3 _geom_angle_publ_flag C1 O3 H3 106.0(10) . . ? C7 N1 C5 119.87(7) . . ? C7 N1 C6 118.25(7) . . ? C5 N1 C6 120.93(7) . . ? C9 O5 H5 106.4(11) . . ? C4 O2 H2 110.7(10) . . ? C3 O6 H6 105.1(12) . . ? C2 O1 H1 107.1(11) . . ? C8 O4 H4 110.2(11) . . ? O5 C9 C6 112.54(7) . . ? O5 C9 H9A 109.1 . . ? C6 C9 H9A 109.1 . . ? O5 C9 H9B 109.1 . . ? C6 C9 H9B 109.1 . . ? H9A C9 H9B 107.8 . . ? O4 C8 C6 109.75(7) . . ? O4 C8 H8A 109.7 . . ? C6 C8 H8A 109.7 . . ? O4 C8 H8B 109.7 . . ? C6 C8 H8B 109.7 . . ? H8A C8 H8B 108.2 . . ? N1 C7 C3 114.52(7) . . ? N1 C7 C2 112.28(7) . . ? C3 C7 C2 109.72(7) . . ? N1 C7 H7A 106.6 . . ? 115 C3 C7 H7A 106.6 . . ? C2 C7 H7A 106.6 . . ? N1 C6 C8 114.54(7) . . ? N1 C6 C9 110.66(7) . . ? C8 C6 C9 110.94(7) . . ? N1 C6 H6A 106.7 . . ? C8 C6 H6A 106.7 . . ? C9 C6 H6A 106.7 . . ? N1 C5 C4 111.95(7) . . ? N1 C5 C1 116.30(8) . . ? C4 C5 C1 110.77(7) . . ? N1 C5 H5A 105.6 . . ? C4 C5 H5A 105.6 . . ? C1 C5 H5A 105.6 . . ? O2 C4 C5 108.58(8) . . ? O2 C4 H4A 110.0 . . ? C5 C4 H4A 110.0 . . ? O2 C4 H4B 110.0 . . ? C5 C4 H4B 110.0 . . ? H4A C4 H4B 108.4 . . ? O6 C3 C7 110.75(8) . . ? O6 C3 H3A 109.5 . . ? C7 C3 H3A 109.5 . . ? O6 C3 H3B 109.5 . . ? C7 C3 H3B 109.5 . . ? H3A C3 H3B 108.1 . . ? O1 C2 C7 112.35(8) . . ? O1 C2 H2A 109.1 . . ? C7 C2 H2A 109.1 . . ? O1 C2 H2B 109.1 . . ? C7 C2 H2B 109.1 . . ? H2A C2 H2B 107.9 . . ? O3 C1 C5 114.65(7) . . ? O3 C1 H1A 108.6 . . ? C5 C1 H1A 108.6 . . ? O3 C1 H1B 108.6 . . ? C5 C1 H1B 108.6 . . ? H1A C1 H1B 107.6 . . ? _diffrn_measured_fraction_theta_max 0.998 _diffrn_reflns_theta_full 28.32 _diffrn_measured_fraction_theta_full 0.998 _refine_diff_density_max 0.360 _refine_diff_density_min -0.166 _refine_diff_density_rms 0.047 116 APPENDIX 2 CRYSTAL STRUCTURE DATA FOR COMPOUND 67 117 data_face(one boron) _audit_creation_method SHELXL-97 _chemical_name_systematic ; ? ; _chemical_name_common ? _chemical_melting_point ? _chemical_formula_moiety ? _chemical_formula_sum 'C9 H18 B N O6' _chemical_formula_weight 247.05 loop_ _atom_type_symbol _atom_type_description _atom_type_scat_dispersion_real _atom_type_scat_dispersion_imag _atom_type_scat_source 'C' 'C' 0.0033 0.0016 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'H' 'H' 0.0000 0.0000 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'N' 'N' 0.0061 0.0033 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'O' 'O' 0.0106 0.0060 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'B' 'B' 0.0013 0.0007 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' _symmetry_cell_setting ? _symmetry_space_group_name_H-M ? loop_ _symmetry_equiv_pos_as_xyz 'x, y, z' '-x+1/2, -y+1/2, z+1/2' '-y, x+1/2, z+1/4' 'y+1/2, -x, z+3/4' 'x, -y, z+1/2' '-x+1/2, y+1/2, z' '-y, -x+1/2, z+3/4' 'y+1/2, x, z+1/4' 'x+1/2, y+1/2, z+1/2' '-x+1, -y+1, z+1' '-y+1/2, x+1, z+3/4' 118 'y+1, -x+1/2, z+5/4' 'x+1/2, -y+1/2, z+1' '-x+1, y+1, z+1/2' '-y+1/2, -x+1, z+5/4' 'y+1, x+1/2, z+3/4' _cell_length_a 16.9503(11) _cell_length_b 16.9503(11) _cell_length_c 14.8701(10) _cell_angle_alpha 90.00 _cell_angle_beta 90.00 _cell_angle_gamma 90.00 _cell_volume 4272.4(5) _cell_formula_units_Z 16 _cell_measurement_temperature 193(2) _cell_measurement_reflns_used ? _cell_measurement_theta_min ? _cell_measurement_theta_max ? _exptl_crystal_description ? _exptl_crystal_colour ? _exptl_crystal_size_max 1.540 _exptl_crystal_size_mid 0.160 _exptl_crystal_size_min 0.156 _exptl_crystal_density_meas ? _exptl_crystal_density_diffrn 1.536 _exptl_crystal_density_method 'not measured' _exptl_crystal_F_000 2112 _exptl_absorpt_coefficient_mu 0.126 _exptl_absorpt_correction_type ? _exptl_absorpt_correction_T_min ? _exptl_absorpt_correction_T_max ? _exptl_absorpt_process_details ? _exptl_special_details ; ? ; _diffrn_ambient_temperature 193(2) _diffrn_radiation_wavelength 0.71073 _diffrn_radiation_type MoK\a _diffrn_radiation_source 'fine-focus sealed tube' _diffrn_radiation_monochromator graphite _diffrn_measurement_device_type ? _diffrn_measurement_method ? _diffrn_detector_area_resol_mean ? _diffrn_standards_number ? _diffrn_standards_interval_count ? _diffrn_standards_interval_time ? _diffrn_standards_decay_% ? _diffrn_reflns_number 20614 119 _diffrn_reflns_av_R_equivalents 0.0257 _diffrn_reflns_av_sigmaI/netI 0.0201 _diffrn_reflns_limit_h_min -22 _diffrn_reflns_limit_h_max 22 _diffrn_reflns_limit_k_min -22 _diffrn_reflns_limit_k_max 22 _diffrn_reflns_limit_l_min -19 _diffrn_reflns_limit_l_max 19 _diffrn_reflns_theta_min 2.40 _diffrn_reflns_theta_max 28.32 _reflns_number_total 2651 _reflns_number_gt 2615 _reflns_threshold_expression >2sigma(I) _computing_data_collection ? _computing_cell_refinement ? _computing_data_reduction ? _computing_structure_solution 'SHELXS-97 (Sheldrick, 1990)' _computing_structure_refinement 'SHELXL-97 (Sheldrick, 1997)' _computing_molecular_graphics ? _computing_publication_material ? _refine_special_details ; Refinement of F^2^ against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F^2^, conventional R-factors R are based on F, with F set to zero for negative F^2^. The threshold expression of F^2^ > 2sigma(F^2^) is used only for calculating R- factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F^2^ are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. ; _refine_ls_structure_factor_coef Fsqd _refine_ls_matrix_type full _refine_ls_weighting_scheme calc _refine_ls_weighting_details 'calc w=1/[\s^2^(Fo^2^)+(0.0673P)^2^+0.2442P] where P=(Fo^2^+2Fc^2^)/3' _atom_sites_solution_primary direct _atom_sites_solution_secondary difmap _atom_sites_solution_hydrogens geom _refine_ls_hydrogen_treatment mixed _refine_ls_extinction_method none 120 _refine_ls_extinction_coef ? _refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881' _refine_ls_abs_structure_Flack 0.6(5) _refine_ls_number_reflns 2651 _refine_ls_number_parameters 226 _refine_ls_number_restraints 1 _refine_ls_R_factor_all 0.0319 _refine_ls_R_factor_gt 0.0316 _refine_ls_wR_factor_ref 0.0807 _refine_ls_wR_factor_gt 0.0804 _refine_ls_goodness_of_fit_ref 1.056 _refine_ls_restrained_S_all 1.056 _refine_ls_shift/su_max 0.002 _refine_ls_shift/su_mean 0.000 loop_ _atom_site_label _atom_site_type_symbol _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_U_iso_or_equiv _atom_site_adp_type _atom_site_occupancy _atom_site_symmetry_multiplicity _atom_site_calc_flag _atom_site_refinement_flags _atom_site_disorder_assembly _atom_site_disorder_group B1 B 0.09550(7) 0.36668(7) 0.33552(8) 0.0217(2) Uani 1 1 d . . . N1 N 0.03293(5) 0.28950(5) 0.32844(6) 0.01637(16) Uani 1 1 d . . . O1 O 0.06661(5) 0.41124(5) 0.41000(6) 0.02660(18) Uani 1 1 d . . . O2 O 0.08735(5) 0.40382(5) 0.24837(5) 0.02675(19) Uani 1 1 d . . . O3 O 0.17149(5) 0.33075(5) 0.34936(6) 0.02599(19) Uani 1 1 d . . . O4 O -0.14732(6) 0.29248(6) 0.47798(7) 0.0315(2) Uani 1 1 d . . . H4 H -0.1544(13) 0.2521(13) 0.5075(17) 0.039(5) Uiso 1 1 d . . . O5 O -0.06881(6) 0.25192(5) 0.10899(6) 0.0298(2) Uani 1 1 d . . . H5 H -0.0683(13) 0.2093(14) 0.0717(16) 0.048(5) Uiso 1 1 d . . . O6 O 0.04810(5) 0.14230(5) 0.46764(5) 0.02376(18) Uani 1 1 d . . . H6 H 0.0056(17) 0.1249(13) 0.4795(16) 0.048(6) Uiso 1 1 d . . . 121 C4 C -0.01544(7) 0.39457(6) 0.41842(8) 0.0244(2) Uani 1 1 d . . . H4A H -0.0471(11) 0.4198(11) 0.3727(13) 0.031(4) Uiso 1 1 d . . . H4B H -0.0342(10) 0.4120(10) 0.4730(13) 0.026(4) Uiso 1 1 d . . . C5 C 0.05972(7) 0.34632(7) 0.18537(7) 0.0244(2) Uani 1 1 d . . . H5A H 0.0408(11) 0.3733(11) 0.1374(13) 0.031(4) Uiso 1 1 d . . . H5B H 0.1026(10) 0.3123(10) 0.1672(12) 0.025(4) Uiso 1 1 d . . . C6 C 0.15896(6) 0.25481(7) 0.38828(8) 0.0240(2) Uani 1 1 d . . . H6A H 0.1476(11) 0.2580(11) 0.4525(14) 0.030(4) Uiso 1 1 d . . . H6B H 0.2023(12) 0.2249(12) 0.3785(15) 0.038(4) Uiso 1 1 d . . . C7 C -0.02155(6) 0.30497(6) 0.40683(7) 0.01882(19) Uani 1 1 d . . . H7 H -0.0010(9) 0.2807(8) 0.4561(10) 0.012(3) Uiso 1 1 d . . . C8 C -0.00365(6) 0.30088(6) 0.23701(7) 0.01886(19) Uani 1 1 d . . . H8 H -0.0442(9) 0.3374(9) 0.2457(12) 0.019(3) Uiso 1 1 d . . . C9 C 0.08895(5) 0.22051(6) 0.33631(7) 0.01901(19) Uani 1 1 d . . . H9 H 0.1074(9) 0.2111(9) 0.2762(11) 0.019(3) Uiso 1 1 d . . . C10 C -0.10551(6) 0.27417(7) 0.39802(8) 0.0234(2) Uani 1 1 d . . . H10A H -0.1068(11) 0.2190(11) 0.3899(13) 0.030(4) Uiso 1 1 d . . . H10B H -0.1327(12) 0.2985(12) 0.3485(15) 0.038(5) Uiso 1 1 d . . . C11 C -0.03248(6) 0.22639(6) 0.19060(7) 0.0217(2) Uani 1 1 d . . . H11A H 0.0117(10) 0.1936(9) 0.1803(12) 0.024(4) Uiso 1 1 d . . . H11B H -0.0717(10) 0.1984(10) 0.2259(12) 0.025(3) Uiso 1 1 d . . . C12 C 0.05740(6) 0.14282(6) 0.37226(7) 0.0207(2) Uani 1 1 d . . . H12A H 0.0098(12) 0.1272(10) 0.3429(14) 0.034(4) Uiso 1 1 d . . . H12B H 0.0945(10) 0.1030(10) 0.3542(11) 0.029(4) Uiso 1 1 d . . . loop_ _atom_site_aniso_label _atom_site_aniso_U_11 122 _atom_site_aniso_U_22 _atom_site_aniso_U_33 _atom_site_aniso_U_23 _atom_site_aniso_U_13 _atom_site_aniso_U_12 B1 0.0222(5) 0.0205(5) 0.0223(5) 0.0017(4) 0.0001(4) - 0.0063(4) N1 0.0170(3) 0.0165(3) 0.0156(4) 0.0022(3) 0.0011(3) 0.0000(3) O1 0.0288(4) 0.0243(4) 0.0267(4) -0.0039(3) -0.0006(3) - 0.0056(3) O2 0.0347(4) 0.0223(4) 0.0232(4) 0.0049(3) -0.0005(3) - 0.0092(3) O3 0.0192(3) 0.0276(4) 0.0311(4) 0.0057(3) 0.0010(3) - 0.0059(3) O4 0.0326(4) 0.0284(4) 0.0335(4) 0.0077(3) 0.0157(4) 0.0070(3) O5 0.0393(5) 0.0302(4) 0.0200(4) -0.0019(3) -0.0072(3) 0.0037(3) O6 0.0233(4) 0.0268(4) 0.0211(4) 0.0040(3) 0.0014(3) - 0.0046(3) C4 0.0272(5) 0.0223(4) 0.0237(5) -0.0017(4) 0.0022(4) 0.0011(3) C5 0.0283(5) 0.0267(5) 0.0184(5) 0.0037(4) 0.0012(4) - 0.0064(4) C6 0.0185(4) 0.0270(5) 0.0264(5) 0.0052(4) -0.0013(4) - 0.0018(4) C7 0.0204(4) 0.0202(4) 0.0159(4) 0.0015(3) 0.0034(3) 0.0013(3) C8 0.0208(4) 0.0193(4) 0.0164(4) 0.0025(3) -0.0006(3) - 0.0004(3) C9 0.0179(4) 0.0190(4) 0.0202(5) 0.0024(3) 0.0011(3) 0.0019(3) C10 0.0206(4) 0.0241(5) 0.0254(5) 0.0027(4) 0.0046(4) - 0.0002(3) C11 0.0241(5) 0.0210(4) 0.0199(4) -0.0003(4) -0.0026(4) - 0.0009(4) C12 0.0231(4) 0.0175(4) 0.0215(5) 0.0022(3) 0.0002(4) 0.0007(3) _geom_special_details ; All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) 123 treatment of cell esds is used for estimating esds involving l.s. planes. ; loop_ _geom_bond_atom_site_label_1 _geom_bond_atom_site_label_2 _geom_bond_distance _geom_bond_site_symmetry_2 _geom_bond_publ_flag B1 O1 1.4272(15) . ? B1 O3 1.4396(14) . ? B1 O2 1.4473(14) . ? B1 N1 1.6875(13) . ? N1 C8 1.5067(12) . ? N1 C7 1.5101(12) . ? N1 C9 1.5109(12) . ? O1 C4 1.4246(14) . ? O2 C5 1.4306(14) . ? O3 C6 1.4273(13) . ? O4 C10 1.4186(13) . ? O4 H4 0.82(2) . ? O5 C11 1.4281(13) . ? O5 H5 0.91(2) . ? O6 C12 1.4270(13) . ? O6 H6 0.80(3) . ? C4 C7 1.5321(15) . ? C4 H4A 0.97(2) . ? C4 H4B 0.920(19) . ? C5 C8 1.5285(14) . ? C5 H5A 0.91(2) . ? C5 H5B 0.967(17) . ? C6 C9 1.5308(14) . ? C6 H6A 0.98(2) . ? C6 H6B 0.90(2) . ? C7 C10 1.5216(14) . ? C7 H7 0.910(14) . ? C8 C11 1.5196(14) . ? C8 H8 0.934(16) . ? C9 C12 1.5186(13) . ? C9 H9 0.961(17) . ? C10 H10A 0.944(19) . ? C10 H10B 0.96(2) . ? C11 H11A 0.946(17) . ? C11 H11B 0.971(17) . ? C12 H12A 0.95(2) . ? C12 H12B 0.962(17) . ? loop_ _geom_angle_atom_site_label_1 _geom_angle_atom_site_label_2 _geom_angle_atom_site_label_3 124 _geom_angle _geom_angle_site_symmetry_1 _geom_angle_site_symmetry_3 _geom_angle_publ_flag O1 B1 O3 114.84(10) . . ? O1 B1 O2 115.59(9) . . ? O3 B1 O2 113.42(9) . . ? O1 B1 N1 104.06(8) . . ? O3 B1 N1 104.08(8) . . ? O2 B1 N1 102.79(8) . . ? C8 N1 C7 115.00(8) . . ? C8 N1 C9 115.32(7) . . ? C7 N1 C9 117.32(7) . . ? C8 N1 B1 102.45(7) . . ? C7 N1 B1 101.63(7) . . ? C9 N1 B1 101.55(7) . . ? C4 O1 B1 107.35(8) . . ? C5 O2 B1 108.74(8) . . ? C6 O3 B1 107.84(8) . . ? C10 O4 H4 109.8(16) . . ? C11 O5 H5 105.8(14) . . ? C12 O6 H6 108.7(18) . . ? O1 C4 C7 104.64(8) . . ? O1 C4 H4A 113.2(11) . . ? C7 C4 H4A 108.8(11) . . ? O1 C4 H4B 110.5(10) . . ? C7 C4 H4B 113.2(10) . . ? H4A C4 H4B 106.6(15) . . ? O2 C5 C8 104.15(8) . . ? O2 C5 H5A 106.7(12) . . ? C8 C5 H5A 113.7(12) . . ? O2 C5 H5B 110.1(11) . . ? C8 C5 H5B 111.6(10) . . ? H5A C5 H5B 110.3(17) . . ? O3 C6 C9 104.66(8) . . ? O3 C6 H6A 112.1(11) . . ? C9 C6 H6A 111.2(11) . . ? O3 C6 H6B 108.6(13) . . ? C9 C6 H6B 109.6(13) . . ? H6A C6 H6B 110.4(18) . . ? N1 C7 C10 116.48(8) . . ? N1 C7 C4 102.57(8) . . ? C10 C7 C4 114.39(8) . . ? N1 C7 H7 108.0(9) . . ? C10 C7 H7 105.8(9) . . ? C4 C7 H7 109.4(8) . . ? N1 C8 C11 115.83(8) . . ? N1 C8 C5 103.22(8) . . ? C11 C8 C5 114.62(9) . . ? N1 C8 H8 105.3(11) . . ? C11 C8 H8 112.1(10) . . ? C5 C8 H8 104.6(10) . . ? 125 N1 C9 C12 118.49(8) . . ? N1 C9 C6 103.44(8) . . ? C12 C9 C6 115.13(9) . . ? N1 C9 H9 105.2(9) . . ? C12 C9 H9 107.3(9) . . ? C6 C9 H9 106.3(10) . . ? O4 C10 C7 108.67(9) . . ? O4 C10 H10A 108.2(12) . . ? C7 C10 H10A 111.9(11) . . ? O4 C10 H10B 108.0(12) . . ? C7 C10 H10B 111.5(12) . . ? H10A C10 H10B 108.4(17) . . ? O5 C11 C8 105.83(8) . . ? O5 C11 H11A 112.4(11) . . ? C8 C11 H11A 108.0(10) . . ? O5 C11 H11B 108.2(10) . . ? C8 C11 H11B 112.4(10) . . ? H11A C11 H11B 110.0(15) . . ? O6 C12 C9 113.21(9) . . ? O6 C12 H12A 111.1(12) . . ? C9 C12 H12A 112.1(11) . . ? O6 C12 H12B 110.2(10) . . ? C9 C12 H12B 106.3(10) . . ? H12A C12 H12B 103.3(15) . . ? _diffrn_measured_fraction_theta_max 0.999 _diffrn_reflns_theta_full 28.32 _diffrn_measured_fraction_theta_full 0.999 _refine_diff_density_max 0.274 _refine_diff_density_min -0.227 _refine_diff_density_rms 0.053 126 APPENDIX 3 CRYSTAL STRUCTURE DATA FOR COMPOUND 71 127 data_p-1 (2 boron + pyridine) _audit_creation_method SHELXL-97 _chemical_name_systematic ; ? ; _chemical_name_common ? _chemical_melting_point ? _chemical_formula_moiety ? _chemical_formula_sum 'C14 H20 B2 N2 O6' _chemical_formula_weight 333.94 loop_ _atom_type_symbol _atom_type_description _atom_type_scat_dispersion_real _atom_type_scat_dispersion_imag _atom_type_scat_source 'C' 'C' 0.0033 0.0016 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'H' 'H' 0.0000 0.0000 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'B' 'B' 0.0013 0.0007 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'N' 'N' 0.0061 0.0033 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'O' 'O' 0.0106 0.0060 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' _symmetry_cell_setting ? _symmetry_space_group_name_H-M ? loop_ _symmetry_equiv_pos_as_xyz 'x, y, z' '-x, -y, -z' _cell_length_a 11.5031(8) _cell_length_b 11.6639(8) _cell_length_c 12.9997(9) _cell_angle_alpha 97.56(3) _cell_angle_beta 92.13(3) _cell_angle_gamma 117.95(3) _cell_volume 1517.55(18) _cell_formula_units_Z 4 _cell_measurement_temperature 193(2) _cell_measurement_reflns_used ? _cell_measurement_theta_min ? _cell_measurement_theta_max ? 128 _exptl_crystal_description ? _exptl_crystal_colour ? _exptl_crystal_size_max 0.16 _exptl_crystal_size_mid 0.16 _exptl_crystal_size_min 0.34 _exptl_crystal_density_meas ? _exptl_crystal_density_diffrn 1.462 _exptl_crystal_density_method 'not measured' _exptl_crystal_F_000 704 _exptl_absorpt_coefficient_mu 0.111 _exptl_absorpt_correction_type ? _exptl_absorpt_correction_T_min 0.9633 _exptl_absorpt_correction_T_max 0.9825 _exptl_absorpt_process_details ? _exptl_special_details ; ? ; _diffrn_ambient_temperature 193(2) _diffrn_radiation_wavelength 0.71073 _diffrn_radiation_type MoK\a _diffrn_radiation_source 'fine-focus sealed tube' _diffrn_radiation_monochromator graphite _diffrn_measurement_device_type ? _diffrn_measurement_method ? _diffrn_detector_area_resol_mean ? _diffrn_standards_number ? _diffrn_standards_interval_count ? _diffrn_standards_interval_time ? _diffrn_standards_decay_% ? _diffrn_reflns_number 15700 _diffrn_reflns_av_R_equivalents 0.0351 _diffrn_reflns_av_sigmaI/netI 0.0587 _diffrn_reflns_limit_h_min -15 _diffrn_reflns_limit_h_max 15 _diffrn_reflns_limit_k_min -15 _diffrn_reflns_limit_k_max 15 _diffrn_reflns_limit_l_min -17 _diffrn_reflns_limit_l_max 17 _diffrn_reflns_theta_min 1.59 _diffrn_reflns_theta_max 28.30 _reflns_number_total 7490 _reflns_number_gt 4658 _reflns_threshold_expression >2sigma(I) _computing_data_collection ? _computing_cell_refinement ? _computing_data_reduction ? _computing_structure_solution 'SHELXS-97 (Sheldrick, 1990)' 129 _computing_structure_refinement 'SHELXL-97 (Sheldrick, 1997)' _computing_molecular_graphics ? _computing_publication_material ? _refine_special_details ; Refinement of F^2^ against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F^2^, conventional R-factors R are based on F, with F set to zero for negative F^2^. The threshold expression of F^2^ > 2sigma(F^2^) is used only for calculating R- factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F^2^ are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. ; _refine_ls_structure_factor_coef Fsqd _refine_ls_matrix_type full _refine_ls_weighting_scheme calc _refine_ls_weighting_details 'calc w=1/[\s^2^(Fo^2^)+(0.1065P)^2^+0.5031P] where P=(Fo^2^+2Fc^2^)/3' _atom_sites_solution_primary direct _atom_sites_solution_secondary difmap _atom_sites_solution_hydrogens geom _refine_ls_hydrogen_treatment mixed _refine_ls_extinction_method none _refine_ls_extinction_coef ? _refine_ls_number_reflns 7490 _refine_ls_number_parameters 433 _refine_ls_number_restraints 0 _refine_ls_R_factor_all 0.1132 _refine_ls_R_factor_gt 0.0762 _refine_ls_wR_factor_ref 0.2235 _refine_ls_wR_factor_gt 0.2046 _refine_ls_goodness_of_fit_ref 1.092 _refine_ls_restrained_S_all 1.092 _refine_ls_shift/su_max 0.060 _refine_ls_shift/su_mean 0.007 loop_ _atom_site_label _atom_site_type_symbol _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z 130 _atom_site_U_iso_or_equiv _atom_site_adp_type _atom_site_occupancy _atom_site_symmetry_multiplicity _atom_site_calc_flag _atom_site_refinement_flags _atom_site_disorder_assembly _atom_site_disorder_group O12 O 0.54794(18) 0.65314(18) 0.11245(15) 0.0360(5) Uani 1 1 d . . . O11 O 0.65986(19) 0.88823(19) 0.17156(15) 0.0360(5) Uani 1 1 d . . . O10 O 0.70195(18) 0.7971(2) 0.00664(15) 0.0378(5) Uani 1 1 d . . . O9 O 1.00268(19) 0.8396(2) 0.35091(16) 0.0432(5) Uani 1 1 d . . . O8 O 1.06281(19) 0.7803(2) 0.18288(16) 0.0399(5) Uani 1 1 d . . . N3 N 0.8404(2) 0.7594(2) 0.19485(16) 0.0277(5) Uani 1 1 d . . . O7 O 0.9052(2) 0.6110(2) 0.26928(17) 0.0430(5) Uani 1 1 d . . . C22 C 0.8905(3) 0.7920(3) 0.0917(2) 0.0313(6) Uani 1 1 d . . . H22A H 0.8637 0.7070 0.0440 0.038 Uiso 1 1 calc R . . N4 N 0.4918(2) 0.7953(2) 0.02290(18) 0.0341(5) Uani 1 1 d . . . C16 C 0.7248(3) 0.6241(3) 0.1924(2) 0.0344(6) Uani 1 1 d . . . H16A H 0.6856 0.6260 0.2596 0.041 Uiso 1 1 calc R . . C19 C 0.8373(3) 0.8700(3) 0.2664(2) 0.0326(6) Uani 1 1 d . . . H19A H 0.9022 0.9540 0.2447 0.039 Uiso 1 1 calc R . . C17 C 0.6139(3) 0.5770(3) 0.1051(2) 0.0374(6) Uani 1 1 d . . . H17A H 0.6508 0.5805 0.0373 0.045 Uiso 1 1 calc R . . H17B H 0.5492 0.4841 0.1068 0.045 Uiso 1 1 calc R . . C21 C 1.0407(3) 0.8598(3) 0.1185(2) 0.0365(6) Uani 1 1 d . . . H21A H 1.0853 0.8633 0.0544 0.044 Uiso 1 1 calc R . . H21B H 1.0742 0.9506 0.1565 0.044 Uiso 1 1 calc R . . C20 C 0.7059(3) 0.8709(3) 0.2669(2) 0.0335(6) Uani 1 1 d . . . H20A H 0.6387 0.7866 0.2848 0.040 Uiso 1 1 calc R . . H20B H 0.7153 0.9425 0.3223 0.040 Uiso 1 1 calc R . . C23 C 0.8404(3) 0.8693(3) 0.0372(2) 0.0343(6) Uani 1 1 d . . . H23A H 0.8609 0.9518 0.0846 0.041 Uiso 1 1 calc R . . H23B H 0.8870 0.8934 -0.0254 0.041 Uiso 1 1 calc R . . C18 C 0.8956(3) 0.8640(3) 0.3715(2) 0.0406(7) Uani 1 1 d . . . H18A H 0.9270 0.9483 0.4198 0.049 Uiso 1 1 calc R . . 131 H18B H 0.8283 0.7924 0.4036 0.049 Uiso 1 1 calc R . . B4 B 0.6121(3) 0.7830(3) 0.0838(2) 0.0316(6) Uani 1 1 d . . . C24 C 0.5052(3) 0.8463(3) -0.0640(2) 0.0445(7) Uani 1 1 d . . . H24A H 0.5859 0.8738 -0.0945 0.053 Uiso 1 1 calc R . . C15 C 0.7909(3) 0.5375(3) 0.1964(3) 0.0438(7) Uani 1 1 d . . . H15A H 0.7304 0.4538 0.2191 0.053 Uiso 1 1 calc R . . H15B H 0.8154 0.5172 0.1267 0.053 Uiso 1 1 calc R . . B3 B 0.9661(3) 0.7465(3) 0.2561(3) 0.0356(7) Uani 1 1 d . . . C28 C 0.3782(3) 0.7571(3) 0.0655(3) 0.0491(8) Uani 1 1 d . . . H28A H 0.3694 0.7220 0.1284 0.059 Uiso 1 1 calc R . . C26 C 0.2869(3) 0.8194(3) -0.0681(3) 0.0546(9) Uani 1 1 d . . . H26A H 0.2160 0.8274 -0.1000 0.065 Uiso 1 1 calc R . . C27 C 0.2741(3) 0.7671(4) 0.0211(3) 0.0581(10) Uani 1 1 d . . . H27A H 0.1938 0.7379 0.0523 0.070 Uiso 1 1 calc R . . C25 C 0.4038(4) 0.8602(4) -0.1111(3) 0.0553(9) Uani 1 1 d . . . H25A H 0.4152 0.8979 -0.1729 0.066 Uiso 1 1 calc R . . O6 O 0.3389(2) 0.6937(2) 0.35640(19) 0.0544(6) Uani 1 1 d . . . N1 N 0.1580(2) 0.3929(2) 0.31308(17) 0.0306(5) Uani 1 1 d . . . O5 O 0.2453(2) 0.6069(2) 0.50763(18) 0.0601(7) Uani 1 1 d . . . N2 N 0.4702(2) 0.7917(2) 0.52717(18) 0.0362(5) Uani 1 1 d . . . O3 O 0.1175(2) 0.1759(2) 0.22368(18) 0.0512(6) Uani 1 1 d . . . O4 O 0.4259(2) 0.5761(2) 0.4439(2) 0.0571(7) Uani 1 1 d . . . O2 O 0.0227(2) 0.2907(2) 0.14279(18) 0.0572(6) Uani 1 1 d . . . O1 O -0.0609(2) 0.1977(2) 0.2980(2) 0.0559(6) Uani 1 1 d . . . B2 B 0.3609(3) 0.6539(3) 0.4527(2) 0.0329(7) Uani 1 1 d . . . C14 C 0.4302(3) 0.8693(3) 0.5838(2) 0.0440(7) Uani 1 1 d . . . H14A H 0.3384 0.8427 0.5818 0.053 Uiso 1 1 calc R . . C10 C 0.5988(3) 0.8291(3) 0.5304(2) 0.0444(7) Uani 1 1 d . . . H10A H 0.6266 0.7746 0.4895 0.053 Uiso 1 1 calc R . . C9 C 0.2189(3) 0.6293(3) 0.2958(2) 0.0437(7) Uani 1 1 d . . . H9A H 0.2218 0.6816 0.2409 0.052 Uiso 1 1 calc R . . H9B H 0.1503 0.6281 0.3401 0.052 Uiso 1 1 calc R . . 132 C7 C 0.0531(3) 0.4228(3) 0.1668(3) 0.0484(8) Uani 1 1 d . . . H7A H -0.0214 0.4298 0.1971 0.058 Uiso 1 1 calc R . . H7B H 0.0692 0.4631 0.1028 0.058 Uiso 1 1 calc R . . C4 C 0.2536(3) 0.2631(3) 0.2417(3) 0.0493(8) Uani 1 1 d . . . H4A H 0.2861 0.3002 0.1780 0.059 Uiso 1 1 calc R . . H4B H 0.3022 0.2166 0.2610 0.059 Uiso 1 1 calc R . . C8 C 0.1756(3) 0.4924(3) 0.2443(3) 0.0482(8) Uani 1 1 d . . . H8A H 0.2494 0.4983 0.2030 0.058 Uiso 1 1 calc R . . C2 C 0.0867(3) 0.3947(3) 0.4056(3) 0.0491(8) Uani 1 1 d . . . H2A H 0.0338 0.4383 0.3869 0.059 Uiso 1 1 calc R . . C6 C 0.4083(3) 0.4863(3) 0.3568(3) 0.0458(8) Uani 1 1 d . . . H6A H 0.4727 0.4537 0.3670 0.055 Uiso 1 1 calc R . . H6B H 0.4311 0.5334 0.2965 0.055 Uiso 1 1 calc R . . C13 C 0.5205(3) 0.9867(3) 0.6447(3) 0.0492(8) Uani 1 1 d . . . H13A H 0.4914 1.0416 0.6832 0.059 Uiso 1 1 calc R . . C5 C 0.2751(3) 0.3706(3) 0.3288(3) 0.0438(7) Uani 1 1 d . . . H5A H 0.2593 0.3271 0.3919 0.053 Uiso 1 1 calc R . . C12 C 0.6529(3) 1.0233(3) 0.6491(3) 0.0507(8) Uani 1 1 d . . . H12A H 0.7162 1.1027 0.6921 0.061 Uiso 1 1 calc R . . C3 C 0.1661(3) 0.4757(3) 0.5067(2) 0.0462(8) Uani 1 1 d . . . H3A H 0.1041 0.4658 0.5598 0.055 Uiso 1 1 calc R . . H3B H 0.2226 0.4383 0.5289 0.055 Uiso 1 1 calc R . . C11 C 0.6927(3) 0.9442(3) 0.5909(3) 0.0524(8) Uani 1 1 d . . . H11A H 0.7840 0.9685 0.5924 0.063 Uiso 1 1 calc R . . C1 C -0.0146(4) 0.2548(4) 0.4029(3) 0.0603(10) Uani 1 1 d . . . H1A H 0.0252 0.2074 0.4355 0.072 Uiso 1 1 calc R . . H1B H -0.0886 0.2503 0.4418 0.072 Uiso 1 1 calc R . . B1 B 0.0463(3) 0.2494(3) 0.2367(3) 0.0423(8) Uani 1 1 d . . . loop_ _atom_site_aniso_label _atom_site_aniso_U_11 _atom_site_aniso_U_22 _atom_site_aniso_U_33 _atom_site_aniso_U_23 _atom_site_aniso_U_13 _atom_site_aniso_U_12 O12 0.0281(10) 0.0321(10) 0.0457(11) 0.0024(8) -0.0031(8) 0.0142(8) 133 O11 0.0371(11) 0.0366(11) 0.0370(11) 0.0004(8) -0.0024(8) 0.0218(9) O10 0.0311(10) 0.0517(12) 0.0333(10) 0.0061(9) 0.0015(8) 0.0225(9) O9 0.0352(11) 0.0547(13) 0.0401(11) 0.0031(10) -0.0074(9) 0.0238(10) O8 0.0306(10) 0.0516(12) 0.0460(12) 0.0166(10) 0.0042(9) 0.0243(9) N3 0.0260(11) 0.0257(11) 0.0310(11) 0.0050(9) 0.0019(9) 0.0120(9) O7 0.0385(11) 0.0423(12) 0.0524(13) 0.0157(10) -0.0017(9) 0.0213(10) C22 0.0298(13) 0.0377(15) 0.0296(13) 0.0062(11) 0.0042(10) 0.0186(12) N4 0.0278(12) 0.0360(13) 0.0389(13) 0.0028(10) -0.0005(9) 0.0168(10) C16 0.0304(14) 0.0280(13) 0.0418(15) 0.0057(11) -0.0009(11) 0.0118(11) C19 0.0322(14) 0.0316(14) 0.0308(14) -0.0022(11) -0.0018(11) 0.0148(11) C17 0.0317(14) 0.0269(14) 0.0478(17) 0.0010(12) -0.0056(12) 0.0114(11) C21 0.0291(14) 0.0453(16) 0.0412(16) 0.0136(13) 0.0065(12) 0.0210(13) C20 0.0324(14) 0.0371(15) 0.0309(14) -0.0009(11) 0.0003(11) 0.0184(12) C23 0.0298(14) 0.0438(16) 0.0351(14) 0.0121(12) 0.0065(11) 0.0208(12) C18 0.0348(15) 0.0490(18) 0.0351(15) 0.0006(13) -0.0038(12) 0.0198(14) B4 0.0253(14) 0.0373(16) 0.0342(16) 0.0036(13) -0.0010(12) 0.0175(13) C24 0.0401(16) 0.060(2) 0.0423(17) 0.0108(15) 0.0030(13) 0.0308(15) C15 0.0387(16) 0.0339(16) 0.059(2) 0.0116(14) -0.0030(14) 0.0172(13) B3 0.0286(15) 0.0419(18) 0.0387(17) 0.0093(14) -0.0040(13) 0.0188(14) C28 0.0389(17) 0.055(2) 0.067(2) 0.0229(17) 0.0146(15) 0.0294(15) C26 0.0400(18) 0.053(2) 0.073(2) -0.0034(18) -0.0120(16) 0.0297(16) C27 0.0339(17) 0.054(2) 0.095(3) 0.023(2) 0.0113(17) 0.0255(16) C25 0.059(2) 0.075(2) 0.0452(19) 0.0146(17) -0.0004(16) 0.042(2) O6 0.0560(14) 0.0335(11) 0.0624(15) 0.0051(10) -0.0239(11) 0.0151(10) N1 0.0302(11) 0.0273(11) 0.0342(12) 0.0011(9) -0.0037(9) 0.0152(9) O5 0.0619(15) 0.0450(13) 0.0492(14) -0.0048(11) 0.0144(12) 0.0083(12) 134 N2 0.0376(13) 0.0306(12) 0.0341(12) 0.0016(10) -0.0032(10) 0.0127(10) O3 0.0479(13) 0.0364(12) 0.0605(14) -0.0111(10) -0.0048(11) 0.0186(10) O4 0.0470(13) 0.0461(13) 0.0744(16) -0.0168(11) -0.0211(11) 0.0279(11) O2 0.0607(15) 0.0415(13) 0.0551(14) -0.0040(10) -0.0248(12) 0.0179(11) O1 0.0412(13) 0.0377(12) 0.0671(16) -0.0066(11) 0.0012(11) 0.0053(10) B2 0.0354(16) 0.0266(15) 0.0347(16) 0.0019(12) 0.0000(13) 0.0144(13) C14 0.0425(17) 0.0361(16) 0.0489(18) -0.0029(13) -0.0058(14) 0.0183(14) C10 0.0388(17) 0.0408(17) 0.0463(18) 0.0014(13) 0.0019(13) 0.0147(14) C9 0.0559(19) 0.0331(15) 0.0406(16) 0.0060(12) -0.0092(14) 0.0211(14) C7 0.059(2) 0.0453(18) 0.0440(18) -0.0070(14) -0.0186(15) 0.0327(16) C4 0.054(2) 0.0422(18) 0.054(2) -0.0085(15) -0.0102(15) 0.0311(16) C8 0.0539(19) 0.0373(17) 0.0468(18) 0.0090(14) -0.0170(15) 0.0176(15) C2 0.0428(17) 0.0405(17) 0.0490(19) -0.0028(14) 0.0126(14) 0.0096(14) C6 0.0375(16) 0.0447(17) 0.0567(19) -0.0092(14) -0.0079(14) 0.0263(14) C13 0.058(2) 0.0352(16) 0.0512(19) -0.0055(14) -0.0060(15) 0.0234(15) C5 0.0384(16) 0.0385(16) 0.0568(19) -0.0052(14) -0.0042(14) 0.0242(14) C12 0.056(2) 0.0301(16) 0.0499(19) -0.0001(14) -0.0128(15) 0.0103(14) C3 0.0449(17) 0.0408(17) 0.0379(16) 0.0038(13) 0.0071(13) 0.0089(14) C11 0.0378(17) 0.0437(19) 0.059(2) 0.0031(15) -0.0032(15) 0.0076(14) C1 0.048(2) 0.049(2) 0.059(2) 0.0085(17) 0.0076(17) 0.0023(16) B1 0.0397(18) 0.0318(17) 0.0454(19) -0.0071(14) -0.0117(15) 0.0136(14) _geom_special_details ; All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles 135 and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. ; loop_ _geom_bond_atom_site_label_1 _geom_bond_atom_site_label_2 _geom_bond_distance _geom_bond_site_symmetry_2 _geom_bond_publ_flag O12 C17 1.410(3) . ? O12 B4 1.449(4) . ? O11 C20 1.406(3) . ? O11 B4 1.436(4) . ? O10 C23 1.418(3) . ? O10 B4 1.436(4) . ? O9 C18 1.415(4) . ? O9 B3 1.435(4) . ? O8 C21 1.427(3) . ? O8 B3 1.436(4) . ? N3 C22 1.503(3) . ? N3 C19 1.503(3) . ? N3 C16 1.508(3) . ? N3 B3 1.703(4) . ? O7 C15 1.414(4) . ? O7 B3 1.436(4) . ? C22 C23 1.508(4) . ? C22 C21 1.528(4) . ? C22 H22A 1.0000 . ? N4 C24 1.327(4) . ? N4 C28 1.336(4) . ? N4 B4 1.642(4) . ? C16 C17 1.513(4) . ? C16 C15 1.527(4) . ? C16 H16A 1.0000 . ? C19 C20 1.516(4) . ? C19 C18 1.525(4) . ? C19 H19A 1.0000 . ? C17 H17A 0.9900 . ? C17 H17B 0.9900 . ? C21 H21A 0.9900 . ? C21 H21B 0.9900 . ? C20 H20A 0.9900 . ? C20 H20B 0.9900 . ? C23 H23A 0.9900 . ? C23 H23B 0.9900 . ? C18 H18A 0.9900 . ? C18 H18B 0.9900 . ? 136 C24 C25 1.382(4) . ? C24 H24A 0.9500 . ? C15 H15A 0.9900 . ? C15 H15B 0.9900 . ? C28 C27 1.371(5) . ? C28 H28A 0.9500 . ? C26 C27 1.362(5) . ? C26 C25 1.369(5) . ? C26 H26A 0.9500 . ? C27 H27A 0.9500 . ? C25 H25A 0.9500 . ? O6 C9 1.372(4) . ? O6 B2 1.445(4) . ? N1 C2 1.484(4) . ? N1 C5 1.499(4) . ? N1 C8 1.501(4) . ? N1 B1 1.700(4) . ? O5 C3 1.364(4) . ? O5 B2 1.438(4) . ? N2 C10 1.328(4) . ? N2 C14 1.346(4) . ? N2 B2 1.645(4) . ? O3 C4 1.399(4) . ? O3 B1 1.437(4) . ? O4 C6 1.375(4) . ? O4 B2 1.418(4) . ? O2 C7 1.398(4) . ? O2 B1 1.431(4) . ? O1 C1 1.400(4) . ? O1 B1 1.423(5) . ? C14 C13 1.379(4) . ? C14 H14A 0.9500 . ? C10 C11 1.374(5) . ? C10 H10A 0.9500 . ? C9 C8 1.482(4) . ? C9 H9A 0.9900 . ? C9 H9B 0.9900 . ? C7 C8 1.505(4) . ? C7 H7A 0.9900 . ? C7 H7B 0.9900 . ? C4 C5 1.492(4) . ? C4 H4A 0.9900 . ? C4 H4B 0.9900 . ? C8 H8A 1.0000 . ? C2 C1 1.490(5) . ? C2 C3 1.493(4) . ? C2 H2A 1.0000 . ? C6 C5 1.480(4) . ? C6 H6A 0.9900 . ? C6 H6B 0.9900 . ? C13 C12 1.372(5) . ? C13 H13A 0.9500 . ? 137 C5 H5A 1.0000 . ? C12 C11 1.368(5) . ? C12 H12A 0.9500 . ? C3 H3A 0.9900 . ? C3 H3B 0.9900 . ? C11 H11A 0.9500 . ? C1 H1A 0.9900 . ? C1 H1B 0.9900 . ? loop_ _geom_angle_atom_site_label_1 _geom_angle_atom_site_label_2 _geom_angle_atom_site_label_3 _geom_angle _geom_angle_site_symmetry_1 _geom_angle_site_symmetry_3 _geom_angle_publ_flag C17 O12 B4 119.0(2) . . ? C20 O11 B4 119.2(2) . . ? C23 O10 B4 119.5(2) . . ? C18 O9 B3 109.0(2) . . ? C21 O8 B3 107.8(2) . . ? C22 N3 C19 115.2(2) . . ? C22 N3 C16 116.2(2) . . ? C19 N3 C16 116.0(2) . . ? C22 N3 B3 101.68(19) . . ? C19 N3 B3 102.4(2) . . ? C16 N3 B3 101.88(19) . . ? C15 O7 B3 109.1(2) . . ? N3 C22 C23 116.2(2) . . ? N3 C22 C21 102.8(2) . . ? C23 C22 C21 114.6(2) . . ? N3 C22 H22A 107.6 . . ? C23 C22 H22A 107.6 . . ? C21 C22 H22A 107.6 . . ? C24 N4 C28 119.1(3) . . ? C24 N4 B4 122.6(2) . . ? C28 N4 B4 118.2(2) . . ? N3 C16 C17 116.5(2) . . ? N3 C16 C15 103.2(2) . . ? C17 C16 C15 115.5(2) . . ? N3 C16 H16A 107.0 . . ? C17 C16 H16A 107.1 . . ? C15 C16 H16A 107.0 . . ? N3 C19 C20 117.0(2) . . ? N3 C19 C18 102.8(2) . . ? C20 C19 C18 115.2(2) . . ? N3 C19 H19A 107.1 . . ? C20 C19 H19A 107.1 . . ? C18 C19 H19A 107.1 . . ? O12 C17 C16 112.6(2) . . ? O12 C17 H17A 109.1 . . ? 138 C16 C17 H17A 109.1 . . ? O12 C17 H17B 109.1 . . ? C16 C17 H17B 109.1 . . ? H17A C17 H17B 107.8 . . ? O8 C21 C22 104.7(2) . . ? O8 C21 H21A 110.8 . . ? C22 C21 H21A 110.8 . . ? O8 C21 H21B 110.8 . . ? C22 C21 H21B 110.8 . . ? H21A C21 H21B 108.9 . . ? O11 C20 C19 114.2(2) . . ? O11 C20 H20A 108.7 . . ? C19 C20 H20A 108.7 . . ? O11 C20 H20B 108.7 . . ? C19 C20 H20B 108.7 . . ? H20A C20 H20B 107.6 . . ? O10 C23 C22 112.1(2) . . ? O10 C23 H23A 109.2 . . ? C22 C23 H23A 109.2 . . ? O10 C23 H23B 109.2 . . ? C22 C23 H23B 109.2 . . ? H23A C23 H23B 107.9 . . ? O9 C18 C19 106.2(2) . . ? O9 C18 H18A 110.5 . . ? C19 C18 H18A 110.5 . . ? O9 C18 H18B 110.5 . . ? C19 C18 H18B 110.5 . . ? H18A C18 H18B 108.7 . . ? O10 B4 O11 115.8(2) . . ? O10 B4 O12 114.0(2) . . ? O11 B4 O12 113.6(2) . . ? O10 B4 N4 103.7(2) . . ? O11 B4 N4 103.4(2) . . ? O12 B4 N4 104.4(2) . . ? N4 C24 C25 121.2(3) . . ? N4 C24 H24A 119.4 . . ? C25 C24 H24A 119.4 . . ? O7 C15 C16 105.9(2) . . ? O7 C15 H15A 110.6 . . ? C16 C15 H15A 110.6 . . ? O7 C15 H15B 110.6 . . ? C16 C15 H15B 110.6 . . ? H15A C15 H15B 108.7 . . ? O9 B3 O7 115.0(3) . . ? O9 B3 O8 115.4(3) . . ? O7 B3 O8 114.4(3) . . ? O9 B3 N3 103.0(2) . . ? O7 B3 N3 103.3(2) . . ? O8 B3 N3 103.3(2) . . ? N4 C28 C27 122.0(3) . . ? N4 C28 H28A 119.0 . . ? C27 C28 H28A 119.0 . . ? 139 C27 C26 C25 118.8(3) . . ? C27 C26 H26A 120.6 . . ? C25 C26 H26A 120.6 . . ? C26 C27 C28 119.3(3) . . ? C26 C27 H27A 120.3 . . ? C28 C27 H27A 120.3 . . ? C26 C25 C24 119.6(3) . . ? C26 C25 H25A 120.2 . . ? C24 C25 H25A 120.2 . . ? C9 O6 B2 122.0(2) . . ? C2 N1 C5 116.5(2) . . ? C2 N1 C8 116.4(3) . . ? C5 N1 C8 114.6(2) . . ? C2 N1 B1 101.7(2) . . ? C5 N1 B1 102.0(2) . . ? C8 N1 B1 102.1(2) . . ? C3 O5 B2 121.3(3) . . ? C10 N2 C14 119.3(3) . . ? C10 N2 B2 120.5(2) . . ? C14 N2 B2 120.2(2) . . ? C4 O3 B1 109.2(2) . . ? C6 O4 B2 124.0(2) . . ? C7 O2 B1 108.4(2) . . ? C1 O1 B1 109.0(2) . . ? O4 B2 O5 116.2(3) . . ? O4 B2 O6 114.4(3) . . ? O5 B2 O6 111.9(3) . . ? O4 B2 N2 103.4(2) . . ? O5 B2 N2 104.8(2) . . ? O6 B2 N2 104.4(2) . . ? N2 C14 C13 121.0(3) . . ? N2 C14 H14A 119.5 . . ? C13 C14 H14A 119.5 . . ? N2 C10 C11 122.0(3) . . ? N2 C10 H10A 119.0 . . ? C11 C10 H10A 119.0 . . ? O6 C9 C8 117.1(3) . . ? O6 C9 H9A 108.0 . . ? C8 C9 H9A 108.0 . . ? O6 C9 H9B 108.0 . . ? C8 C9 H9B 108.0 . . ? H9A C9 H9B 107.3 . . ? O2 C7 C8 107.7(3) . . ? O2 C7 H7A 110.2 . . ? C8 C7 H7A 110.2 . . ? O2 C7 H7B 110.2 . . ? C8 C7 H7B 110.2 . . ? H7A C7 H7B 108.5 . . ? O3 C4 C5 107.6(3) . . ? O3 C4 H4A 110.2 . . ? C5 C4 H4A 110.2 . . ? O3 C4 H4B 110.2 . . ? 140 C5 C4 H4B 110.2 . . ? H4A C4 H4B 108.5 . . ? C9 C8 N1 117.6(3) . . ? C9 C8 C7 119.3(3) . . ? N1 C8 C7 103.7(2) . . ? C9 C8 H8A 104.9 . . ? N1 C8 H8A 104.9 . . ? C7 C8 H8A 104.9 . . ? N1 C2 C1 105.0(3) . . ? N1 C2 C3 118.3(3) . . ? C1 C2 C3 119.4(3) . . ? N1 C2 H2A 104.0 . . ? C1 C2 H2A 104.0 . . ? C3 C2 H2A 104.0 . . ? O4 C6 C5 117.4(3) . . ? O4 C6 H6A 107.9 . . ? C5 C6 H6A 107.9 . . ? O4 C6 H6B 108.0 . . ? C5 C6 H6B 108.0 . . ? H6A C6 H6B 107.2 . . ? C12 C13 C14 119.3(3) . . ? C12 C13 H13A 120.4 . . ? C14 C13 H13A 120.4 . . ? C6 C5 C4 119.8(3) . . ? C6 C5 N1 118.8(2) . . ? C4 C5 N1 104.9(2) . . ? C6 C5 H5A 103.7 . . ? C4 C5 H5A 103.7 . . ? N1 C5 H5A 103.7 . . ? C11 C12 C13 119.3(3) . . ? C11 C12 H12A 120.4 . . ? C13 C12 H12A 120.4 . . ? O5 C3 C2 117.0(3) . . ? O5 C3 H3A 108.1 . . ? C2 C3 H3A 108.1 . . ? O5 C3 H3B 108.1 . . ? C2 C3 H3B 108.1 . . ? H3A C3 H3B 107.3 . . ? C12 C11 C10 119.1(3) . . ? C12 C11 H11A 120.4 . . ? C10 C11 H11A 120.4 . . ? O1 C1 C2 107.6(3) . . ? O1 C1 H1A 110.2 . . ? C2 C1 H1A 110.2 . . ? O1 C1 H1B 110.2 . . ? C2 C1 H1B 110.2 . . ? H1A C1 H1B 108.5 . . ? O1 B1 O2 117.0(3) . . ? O1 B1 O3 114.5(3) . . ? O2 B1 O3 113.3(3) . . ? O1 B1 N1 103.4(2) . . ? O2 B1 N1 103.3(2) . . ? 141 O3 B1 N1 103.0(2) . . ? _diffrn_measured_fraction_theta_max 0.990 _diffrn_reflns_theta_full 28.30 _diffrn_measured_fraction_theta_full 0.990 _refine_diff_density_max 1.301 _refine_diff_density_min -0.561 _refine_diff_density_rms 0.065 142 APPENDIX 4 CRYSTAL STRUCTURE DATA FOR COMPOUND 74 143 data_final(2Ph,2Si) _audit_creation_method SHELXL-97 _chemical_name_systematic ; ? ; _chemical_name_common ? _chemical_melting_point ? _chemical_formula_moiety ? _chemical_formula_sum 'C21 H25 N O6 Si2' _chemical_formula_weight 443.60 loop_ _atom_type_symbol _atom_type_description _atom_type_scat_dispersion_real _atom_type_scat_dispersion_imag _atom_type_scat_source 'C' 'C' 0.0033 0.0016 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'H' 'H' 0.0000 0.0000 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'N' 'N' 0.0061 0.0033 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'O' 'O' 0.0106 0.0060 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'Si' 'Si' 0.0817 0.0704 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' _symmetry_cell_setting ? _symmetry_space_group_name_H-M ? loop_ _symmetry_equiv_pos_as_xyz 'x, y, z' '-x, y+1/2, -z+1/2' '-x, -y, -z' 'x, -y-1/2, z-1/2' _cell_length_a 10.483(2) _cell_length_b 11.489(2) _cell_length_c 17.440(4) _cell_angle_alpha 90.00 _cell_angle_beta 101.86(3) _cell_angle_gamma 90.00 _cell_volume 2055.7(7) _cell_formula_units_Z 4 _cell_measurement_temperature 193(2) _cell_measurement_reflns_used ? _cell_measurement_theta_min ? 144 _cell_measurement_theta_max ? _exptl_crystal_description ? _exptl_crystal_colour ? _exptl_crystal_size_max 0.325 _exptl_crystal_size_mid 0.290 _exptl_crystal_size_min 0.280 _exptl_crystal_density_meas ? _exptl_crystal_density_diffrn 1.433 _exptl_crystal_density_method 'not measured' _exptl_crystal_F_000 936 _exptl_absorpt_coefficient_mu 0.212 _exptl_absorpt_correction_type ? _exptl_absorpt_correction_T_min ? _exptl_absorpt_correction_T_max ? _exptl_absorpt_process_details ? _exptl_special_details ; ? ; _diffrn_ambient_temperature 193(2) _diffrn_radiation_wavelength 0.71073 _diffrn_radiation_type MoK\a _diffrn_radiation_source 'fine-focus sealed tube' _diffrn_radiation_monochromator graphite _diffrn_measurement_device_type ? _diffrn_measurement_method ? _diffrn_detector_area_resol_mean ? _diffrn_standards_number ? _diffrn_standards_interval_count ? _diffrn_standards_interval_time ? _diffrn_standards_decay_% ? _diffrn_reflns_number 16579 _diffrn_reflns_av_R_equivalents 0.0689 _diffrn_reflns_av_sigmaI/netI 0.0632 _diffrn_reflns_limit_h_min -13 _diffrn_reflns_limit_h_max 13 _diffrn_reflns_limit_k_min -15 _diffrn_reflns_limit_k_max 15 _diffrn_reflns_limit_l_min -23 _diffrn_reflns_limit_l_max 22 _diffrn_reflns_theta_min 2.39 _diffrn_reflns_theta_max 28.36 _reflns_number_total 4672 _reflns_number_gt 3223 _reflns_threshold_expression >2sigma(I) _computing_data_collection ? _computing_cell_refinement ? _computing_data_reduction ? 145 _computing_structure_solution 'SHELXS-97 (Sheldrick, 1990)' _computing_structure_refinement 'SHELXL-97 (Sheldrick, 1997)' _computing_molecular_graphics ? _computing_publication_material ? _refine_special_details ; Refinement of F^2^ against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F^2^, conventional R-factors R are based on F, with F set to zero for negative F^2^. The threshold expression of F^2^ > 2sigma(F^2^) is used only for calculating R- factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F^2^ are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. ; _refine_ls_structure_factor_coef Fsqd _refine_ls_matrix_type full _refine_ls_weighting_scheme calc _refine_ls_weighting_details 'calc w=1/[\s^2^(Fo^2^)+(0.1000P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3' _atom_sites_solution_primary direct _atom_sites_solution_secondary difmap _atom_sites_solution_hydrogens geom _refine_ls_hydrogen_treatment mixed _refine_ls_extinction_method none _refine_ls_extinction_coef ? _refine_ls_number_reflns 4672 _refine_ls_number_parameters 271 _refine_ls_number_restraints 0 _refine_ls_R_factor_all 0.1253 _refine_ls_R_factor_gt 0.0977 _refine_ls_wR_factor_ref 0.2892 _refine_ls_wR_factor_gt 0.2747 _refine_ls_goodness_of_fit_ref 1.819 _refine_ls_restrained_S_all 1.819 _refine_ls_shift/su_max 0.185 _refine_ls_shift/su_mean 0.026 loop_ _atom_site_label _atom_site_type_symbol 146 _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_U_iso_or_equiv _atom_site_adp_type _atom_site_occupancy _atom_site_symmetry_multiplicity _atom_site_calc_flag _atom_site_refinement_flags _atom_site_disorder_assembly _atom_site_disorder_group Si1 Si 0.48882(9) 0.55136(10) 0.22916(5) 0.0266(3) Uani 1 1 d . . . Si2 Si 0.83179(9) 0.61170(10) 0.53180(5) 0.0274(3) Uani 1 1 d . . . O6 O 0.8433(3) 0.4768(3) 0.50714(18) 0.0461(8) Uani 1 1 d . . . O1 O 0.3960(3) 0.6020(3) 0.28613(16) 0.0447(9) Uani 1 1 d . . . O3 O 0.5467(3) 0.4240(3) 0.25279(17) 0.0478(9) Uani 1 1 d . . . N1 N 0.6531(3) 0.5809(3) 0.37369(18) 0.0276(7) Uani 1 1 d . . . O5 O 0.6835(3) 0.6390(3) 0.54200(16) 0.0458(9) Uani 1 1 d . . . O2 O 0.5979(3) 0.6443(3) 0.21421(17) 0.0473(9) Uani 1 1 d . . . C10 C 0.3772(4) 0.5344(4) 0.1321(2) 0.0294(8) Uani 1 1 d . . . C16 C 0.9398(3) 0.6346(4) 0.6289(2) 0.0297(9) Uani 1 1 d . . . O4 O 0.8786(3) 0.7007(3) 0.47127(16) 0.0449(8) Uani 1 1 d . . . C6 C 0.8721(3) 0.6778(4) 0.3897(2) 0.0339(10) Uani 1 1 d . . . H6A H 0.9166 0.6034 0.3838 0.041 Uiso 1 1 calc R . . H6B H 0.9179 0.7404 0.3672 0.041 Uiso 1 1 calc R . . C19 C 1.0988(4) 0.6674(4) 0.7770(2) 0.0391(10) Uani 1 1 d . . . H19A H 1.1526 0.6786 0.8274 0.047 Uiso 1 1 calc R . . C7 C 0.5905(4) 0.3807(4) 0.3307(2) 0.0306(8) Uani 1 1 d . . . H7A H 0.6247 0.3007 0.3284 0.037 Uiso 1 1 calc R . . H7B H 0.5160 0.3773 0.3575 0.037 Uiso 1 1 calc R . . C8 C 0.6972(4) 0.4586(4) 0.3774(2) 0.0396(10) Uani 1 1 d . . . H8A H 0.7742 0.4541 0.3518 0.047 Uiso 1 1 calc R . . C9 C 0.7391(4) 0.4116(4) 0.4602(2) 0.0308(9) Uani 1 1 d . . . H9A H 0.6633 0.4125 0.4859 0.037 Uiso 1 1 calc R . . H9B H 0.7672 0.3297 0.4575 0.037 Uiso 1 1 calc R . . 147 C4 C 0.7277(4) 0.6544(4) 0.2573(2) 0.0350(10) Uani 1 1 d . . . H4A H 0.7704 0.7216 0.2374 0.042 Uiso 1 1 calc R . . H4B H 0.7770 0.5833 0.2497 0.042 Uiso 1 1 calc R . . C21 C 0.9342(4) 0.5594(4) 0.6908(2) 0.0345(10) Uani 1 1 d . . . H21A H 0.8747 0.4961 0.6826 0.041 Uiso 1 1 calc R . . C15 C 0.2534(4) 0.4864(4) 0.1262(2) 0.0331(9) Uani 1 1 d . . . H15A H 0.2267 0.4615 0.1724 0.040 Uiso 1 1 calc R . . C5 C 0.7306(4) 0.6712(4) 0.3449(2) 0.0362(10) Uani 1 1 d . . . H5A H 0.6888 0.7479 0.3512 0.043 Uiso 1 1 calc R . . C3 C 0.5894(3) 0.6950(4) 0.4811(2) 0.0335(9) Uani 1 1 d . . . H3A H 0.6281 0.7666 0.4640 0.040 Uiso 1 1 calc R . . H3B H 0.5122 0.7177 0.5021 0.040 Uiso 1 1 calc R . . C20 C 1.0138(4) 0.5750(5) 0.7640(2) 0.0398(11) Uani 1 1 d . . . H20A H 1.0095 0.5219 0.8051 0.048 Uiso 1 1 calc R . . C18 C 1.1059(4) 0.7445(4) 0.7165(2) 0.0393(10) Uani 1 1 d . . . H18A H 1.1646 0.8083 0.7252 0.047 Uiso 1 1 calc R . . C2 C 0.5475(4) 0.6154(4) 0.4117(2) 0.0358(10) Uani 1 1 d . . . H2A H 0.5126 0.5428 0.4315 0.043 Uiso 1 1 calc R . . C13 C 0.2068(5) 0.5121(5) -0.0134(3) 0.0474(12) Uani 1 1 d . . . H13A H 0.1499 0.5036 -0.0631 0.057 Uiso 1 1 calc R . . C11 C 0.4118(4) 0.5744(5) 0.0634(2) 0.0410(11) Uani 1 1 d . . . H11A H 0.4941 0.6105 0.0659 0.049 Uiso 1 1 calc R . . C1 C 0.4354(3) 0.6714(4) 0.3526(2) 0.0333(9) Uani 1 1 d . . . H1A H 0.3604 0.6841 0.3780 0.040 Uiso 1 1 calc R . . H1B H 0.4638 0.7482 0.3366 0.040 Uiso 1 1 calc R . . C17 C 1.0268(4) 0.7274(4) 0.6435(2) 0.0347(9) Uani 1 1 d . . . H17A H 1.0319 0.7803 0.6024 0.042 Uiso 1 1 calc R . . C14 C 0.1682(4) 0.4740(4) 0.0543(2) 0.0407(11) Uani 1 1 d . . . H14A H 0.0847 0.4400 0.0513 0.049 Uiso 1 1 calc R . . C12 C 0.3273(5) 0.5618(5) -0.0080(2) 0.0509(13) Uani 1 1 d . . . H12A H 0.3530 0.5880 -0.0542 0.061 Uiso 1 1 calc R . . loop_ _atom_site_aniso_label _atom_site_aniso_U_11 _atom_site_aniso_U_22 _atom_site_aniso_U_33 _atom_site_aniso_U_23 148 _atom_site_aniso_U_13 _atom_site_aniso_U_12 Si1 0.0248(5) 0.0307(7) 0.0233(5) 0.0025(4) 0.0028(4) 0.0006(4) Si2 0.0234(5) 0.0339(8) 0.0240(5) -0.0006(4) 0.0026(4) - 0.0018(4) O6 0.0384(17) 0.050(2) 0.0441(17) 0.0014(15) -0.0054(13) - 0.0031(14) O1 0.0301(14) 0.065(3) 0.0354(15) -0.0146(14) -0.0009(12) 0.0077(14) O3 0.066(2) 0.037(2) 0.0325(15) -0.0032(13) -0.0101(14) 0.0041(16) N1 0.0258(15) 0.0233(19) 0.0377(17) 0.0059(13) 0.0160(13) 0.0013(13) O5 0.0367(15) 0.066(3) 0.0335(15) -0.0006(14) 0.0033(12) 0.0062(15) O2 0.0335(15) 0.068(3) 0.0372(15) 0.0146(15) 0.0007(12) - 0.0106(15) C10 0.0298(18) 0.030(2) 0.0275(17) 0.0039(15) 0.0030(14) 0.0027(15) C16 0.0232(16) 0.036(2) 0.0298(17) -0.0046(16) 0.0050(13) 0.0014(15) O4 0.0426(17) 0.055(2) 0.0350(15) -0.0009(14) 0.0043(12) - 0.0131(15) C6 0.0244(17) 0.050(3) 0.0278(17) 0.0022(17) 0.0069(13) - 0.0067(16) C19 0.0270(18) 0.055(3) 0.0327(19) -0.0077(19) 0.0005(15) 0.0002(18) C7 0.0371(19) 0.024(2) 0.0263(17) 0.0012(14) -0.0032(14) - 0.0006(16) C8 0.036(2) 0.042(3) 0.039(2) 0.0012(18) 0.0041(16) - 0.0029(18) C9 0.0324(19) 0.027(2) 0.0305(18) 0.0017(15) 0.0003(14) - 0.0043(16) C4 0.0258(17) 0.050(3) 0.0295(18) 0.0048(17) 0.0063(14) - 0.0090(17) C21 0.0302(19) 0.044(3) 0.0289(18) -0.0011(17) 0.0040(15) - 0.0039(17) C15 0.0294(18) 0.036(3) 0.0331(19) 0.0020(16) 0.0035(14) 0.0040(16) C5 0.0318(19) 0.040(3) 0.037(2) 0.0043(18) 0.0090(15) - 0.0036(17) C3 0.0245(17) 0.043(3) 0.0318(18) -0.0046(17) 0.0033(14) 0.0068(16) C20 0.032(2) 0.061(3) 0.0260(18) 0.0002(18) 0.0047(15) - 0.0007(19) C18 0.0288(19) 0.046(3) 0.041(2) -0.0134(19) 0.0036(16) - 0.0067(18) C2 0.0309(19) 0.043(3) 0.0331(19) -0.0005(17) 0.0066(15) 0.0033(17) C13 0.045(2) 0.057(3) 0.033(2) 0.000(2) -0.0104(18) 0.003(2) 149 C11 0.036(2) 0.053(3) 0.0318(19) 0.0104(19) 0.0017(16) - 0.005(2) C1 0.0242(17) 0.047(3) 0.0284(17) -0.0010(17) 0.0038(13) 0.0065(16) C17 0.0305(18) 0.037(3) 0.0357(19) -0.0026(17) 0.0047(15) 0.0021(17) C14 0.032(2) 0.047(3) 0.038(2) 0.0021(19) -0.0035(16) 0.0040(18) C12 0.058(3) 0.068(4) 0.0254(19) 0.014(2) 0.0046(18) - 0.001(3) _geom_special_details ; All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. ; loop_ _geom_bond_atom_site_label_1 _geom_bond_atom_site_label_2 _geom_bond_distance _geom_bond_site_symmetry_2 _geom_bond_publ_flag Si1 O3 1.606(4) . ? Si1 O2 1.624(3) . ? Si1 O1 1.634(3) . ? Si1 C10 1.859(4) . ? Si2 O4 1.616(3) . ? Si2 O6 1.619(4) . ? Si2 O5 1.631(3) . ? Si2 C16 1.851(4) . ? O6 C9 1.435(5) . ? O1 C1 1.397(5) . ? O3 C7 1.431(4) . ? N1 C2 1.458(5) . ? N1 C8 1.477(6) . ? N1 C5 1.467(5) . ? O5 C3 1.444(5) . ? O2 C4 1.417(4) . ? C10 C11 1.400(5) . ? C10 C15 1.394(5) . ? 150 C16 C17 1.392(6) . ? C16 C21 1.393(6) . ? O4 C6 1.435(4) . ? C6 C5 1.530(5) . ? C19 C20 1.374(7) . ? C19 C18 1.392(6) . ? C7 C8 1.529(6) . ? C8 C9 1.519(5) . ? C4 C5 1.535(5) . ? C21 C20 1.385(5) . ? C15 C14 1.389(5) . ? C3 C2 1.507(6) . ? C18 C17 1.383(5) . ? C2 C1 1.536(5) . ? C13 C12 1.372(7) . ? C13 C14 1.396(6) . ? C11 C12 1.379(6) . ? loop_ _geom_angle_atom_site_label_1 _geom_angle_atom_site_label_2 _geom_angle_atom_site_label_3 _geom_angle _geom_angle_site_symmetry_1 _geom_angle_site_symmetry_3 _geom_angle_publ_flag O3 Si1 O2 113.51(19) . . ? O3 Si1 O1 114.17(18) . . ? O2 Si1 O1 113.0(2) . . ? O3 Si1 C10 105.80(17) . . ? O2 Si1 C10 104.78(16) . . ? O1 Si1 C10 104.39(16) . . ? O4 Si2 O6 112.49(18) . . ? O4 Si2 O5 111.96(18) . . ? O6 Si2 O5 109.73(18) . . ? O4 Si2 C16 107.25(17) . . ? O6 Si2 C16 108.29(18) . . ? O5 Si2 C16 106.88(16) . . ? C9 O6 Si2 124.2(3) . . ? C1 O1 Si1 126.6(2) . . ? C7 O3 Si1 126.2(3) . . ? C2 N1 C8 119.9(3) . . ? C2 N1 C5 119.2(4) . . ? C8 N1 C5 119.9(3) . . ? C3 O5 Si2 121.8(3) . . ? C4 O2 Si1 126.8(3) . . ? C11 C10 C15 117.9(3) . . ? C11 C10 Si1 121.3(3) . . ? C15 C10 Si1 120.8(3) . . ? C17 C16 C21 117.6(3) . . ? C17 C16 Si2 122.1(3) . . ? C21 C16 Si2 120.4(3) . . ? 151 C6 O4 Si2 125.0(3) . . ? O4 C6 C5 111.0(3) . . ? C20 C19 C18 120.0(4) . . ? O3 C7 C8 111.0(3) . . ? N1 C8 C9 113.9(4) . . ? N1 C8 C7 110.3(3) . . ? C9 C8 C7 109.6(4) . . ? O6 C9 C8 113.3(3) . . ? O2 C4 C5 111.0(3) . . ? C20 C21 C16 121.4(4) . . ? C14 C15 C10 121.6(4) . . ? N1 C5 C6 114.0(3) . . ? N1 C5 C4 110.6(3) . . ? C6 C5 C4 109.4(3) . . ? O5 C3 C2 111.3(4) . . ? C19 C20 C21 120.0(4) . . ? C17 C18 C19 119.5(4) . . ? N1 C2 C3 114.0(3) . . ? N1 C2 C1 110.9(3) . . ? C3 C2 C1 110.0(4) . . ? C12 C13 C14 119.7(4) . . ? C12 C11 C10 120.4(4) . . ? O1 C1 C2 111.9(4) . . ? C18 C17 C16 121.6(4) . . ? C15 C14 C13 119.2(4) . . ? C13 C12 C11 121.2(4) . . ? _diffrn_measured_fraction_theta_max 0.911 _diffrn_reflns_theta_full 28.36 _diffrn_measured_fraction_theta_full 0.911 _refine_diff_density_max 1.397 _refine_diff_density_min -0.448 _refine_diff_density_rms 0.103 152 APPENDIX 5 CRYSTAL STRUCTURE DATA FOR COMPOUND 76 153 data_p21n (2Me 2Si) _audit_creation_method SHELXL-97 _chemical_name_systematic ; ? ; _chemical_name_common ? _chemical_melting_point ? _chemical_formula_moiety ? _chemical_formula_sum 'C11 H21 N O6 Si2' _chemical_formula_weight 319.47 loop_ _atom_type_symbol _atom_type_description _atom_type_scat_dispersion_real _atom_type_scat_dispersion_imag _atom_type_scat_source 'C' 'C' 0.0033 0.0016 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'H' 'H' 0.0000 0.0000 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'N' 'N' 0.0061 0.0033 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'O' 'O' 0.0106 0.0060 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'Si' 'Si' 0.0817 0.0704 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' _symmetry_cell_setting ? _symmetry_space_group_name_H-M ? loop_ _symmetry_equiv_pos_as_xyz 'x, y, z' '-x+1/2, y+1/2, -z+1/2' '-x, -y, -z' 'x-1/2, -y-1/2, z-1/2' _cell_length_a 10.2030(6) _cell_length_b 11.1393(7) _cell_length_c 26.179(2) _cell_angle_alpha 90.0000(10) _cell_angle_beta 98.2610(10) _cell_angle_gamma 90.0000(10) _cell_volume 2944.5(3) _cell_formula_units_Z 8 _cell_measurement_temperature 193(2) _cell_measurement_reflns_used ? _cell_measurement_theta_min ? 154 _cell_measurement_theta_max ? _exptl_crystal_description ? _exptl_crystal_colour ? _exptl_crystal_size_max 0.183 _exptl_crystal_size_mid 0.138 _exptl_crystal_size_min 0.113 _exptl_crystal_density_meas ? _exptl_crystal_density_diffrn 1.441 _exptl_crystal_density_method 'not measured' _exptl_crystal_F_000 1360 _exptl_absorpt_coefficient_mu 0.265 _exptl_absorpt_correction_type ? _exptl_absorpt_correction_T_min ? _exptl_absorpt_correction_T_max ? _exptl_absorpt_process_details ? _exptl_special_details ; ? ; _diffrn_ambient_temperature 193(2) _diffrn_radiation_wavelength 0.71073 _diffrn_radiation_type MoK\a _diffrn_radiation_source 'fine-focus sealed tube' _diffrn_radiation_monochromator graphite _diffrn_measurement_device_type ? _diffrn_measurement_method ? _diffrn_detector_area_resol_mean ? _diffrn_standards_number ? _diffrn_standards_interval_count ? _diffrn_standards_interval_time ? _diffrn_standards_decay_% ? _diffrn_reflns_number 29407 _diffrn_reflns_av_R_equivalents 0.0527 _diffrn_reflns_av_sigmaI/netI 0.0523 _diffrn_reflns_limit_h_min -13 _diffrn_reflns_limit_h_max 13 _diffrn_reflns_limit_k_min -14 _diffrn_reflns_limit_k_max 14 _diffrn_reflns_limit_l_min -34 _diffrn_reflns_limit_l_max 34 _diffrn_reflns_theta_min 1.57 _diffrn_reflns_theta_max 28.30 _reflns_number_total 7280 _reflns_number_gt 4542 _reflns_threshold_expression >2sigma(I) _computing_data_collection ? _computing_cell_refinement ? _computing_data_reduction ? 155 _computing_structure_solution 'SHELXS-97 (Sheldrick, 1990)' _computing_structure_refinement 'SHELXL-97 (Sheldrick, 1997)' _computing_molecular_graphics ? _computing_publication_material ? _refine_special_details ; Refinement of F^2^ against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F^2^, conventional R-factors R are based on F, with F set to zero for negative F^2^. The threshold expression of F^2^ > 2sigma(F^2^) is used only for calculating R- factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F^2^ are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. ; _refine_ls_structure_factor_coef Fsqd _refine_ls_matrix_type full _refine_ls_weighting_scheme calc _refine_ls_weighting_details 'calc w=1/[\s^2^(Fo^2^)+(0.1833P)^2^+4.1469P] where P=(Fo^2^+2Fc^2^)/3' _atom_sites_solution_primary direct _atom_sites_solution_secondary difmap _atom_sites_solution_hydrogens geom _refine_ls_hydrogen_treatment mixed _refine_ls_extinction_method none _refine_ls_extinction_coef ? _refine_ls_number_reflns 7280 _refine_ls_number_parameters 361 _refine_ls_number_restraints 0 _refine_ls_R_factor_all 0.1389 _refine_ls_R_factor_gt 0.1010 _refine_ls_wR_factor_ref 0.3176 _refine_ls_wR_factor_gt 0.2919 _refine_ls_goodness_of_fit_ref 1.053 _refine_ls_restrained_S_all 1.053 _refine_ls_shift/su_max 0.019 _refine_ls_shift/su_mean 0.002 loop_ _atom_site_label _atom_site_type_symbol _atom_site_fract_x 156 _atom_site_fract_y _atom_site_fract_z _atom_site_U_iso_or_equiv _atom_site_adp_type _atom_site_occupancy _atom_site_symmetry_multiplicity _atom_site_calc_flag _atom_site_refinement_flags _atom_site_disorder_assembly _atom_site_disorder_group Si1 Si 0.17214(12) 0.02308(12) 0.21167(5) 0.0360(3) Uani 1 1 d . . . Si2 Si 0.72677(12) -0.00490(12) 0.30450(5) 0.0358(3) Uani 1 1 d . . . Si3 Si 0.43038(13) 0.77084(14) -0.04806(5) 0.0403(4) Uani 1 1 d . . . Si4 Si 0.98766(12) 0.76011(12) 0.04252(5) 0.0355(3) Uani 1 1 d . . . N1 N 0.4448(3) 0.0087(3) 0.25741(13) 0.0279(8) Uani 1 1 d . . . N2 N 0.7135(3) 0.7642(3) -0.00160(13) 0.0299(8) Uani 1 1 d . . . O1 O 0.2481(4) 0.1264(4) 0.18562(17) 0.0623(12) Uani 1 1 d . . . O2 O 0.1770(3) 0.0413(5) 0.27364(15) 0.0622(12) Uani 1 1 d . . . O3 O 0.2226(4) -0.1134(4) 0.20063(17) 0.0573(11) Uani 1 1 d . . . O4 O 0.7127(4) 0.0979(4) 0.26035(19) 0.0664(12) Uani 1 1 d . . . O5 O 0.6405(4) 0.0274(4) 0.35035(16) 0.0633(12) Uani 1 1 d . . . O6 O 0.6833(4) -0.1359(4) 0.28068(16) 0.0594(11) Uani 1 1 d . . . O7 O 0.5157(3) 0.8396(4) -0.08778(13) 0.0480(9) Uani 1 1 d . . . O8 O 0.4440(3) 0.8398(4) 0.00739(13) 0.0478(9) Uani 1 1 d . . . O9 O 0.4741(3) 0.6305(3) -0.04018(15) 0.0490(9) Uani 1 1 d . . . O10 O 0.9801(3) 0.8301(4) -0.01240(14) 0.0481(9) Uani 1 1 d . . . O11 O 0.9081(3) 0.8304(3) 0.08328(13) 0.0462(9) Uani 1 1 d . . . O12 O 0.9405(3) 0.6212(3) 0.03409(14) 0.0444(8) Uani 1 1 d . . . C1 C 0.3662(5) 0.1879(4) 0.2072(2) 0.0451(12) Uani 1 1 d . . . H1A H 0.3490 0.2344 0.2378 0.054 Uiso 1 1 calc R . . H1B H 0.3923 0.2450 0.1815 0.054 Uiso 1 1 calc R . . C2 C 0.4795(5) 0.0995(5) 0.2231(2) 0.0458(12) Uani 1 1 d . . . 157 H2A H 0.5011 0.0592 0.1912 0.055 Uiso 1 1 calc R . . C3 C 0.6019(5) 0.1738(5) 0.2467(2) 0.0496(13) Uani 1 1 d . . . H3A H 0.6228 0.2343 0.2214 0.060 Uiso 1 1 calc R . . H3B H 0.5818 0.2168 0.2777 0.060 Uiso 1 1 calc R . . C4 C 0.2709(4) -0.0005(5) 0.31373(18) 0.0403(11) Uani 1 1 d . . . H4A H 0.2674 -0.0893 0.3145 0.048 Uiso 1 1 calc R . . H4B H 0.2483 0.0296 0.3470 0.048 Uiso 1 1 calc R . . C5 C 0.4122(5) 0.0390(5) 0.3082(2) 0.0476(12) Uani 1 1 d . . . H5A H 0.4159 0.1284 0.3116 0.057 Uiso 1 1 calc R . . C6 C 0.5092(5) -0.0130(5) 0.35209(18) 0.0445(12) Uani 1 1 d . . . H6A H 0.4819 0.0106 0.3855 0.053 Uiso 1 1 calc R . . H6B H 0.5068 -0.1017 0.3499 0.053 Uiso 1 1 calc R . . C7 C 0.3558(4) -0.1447(4) 0.19404(19) 0.0377(10) Uani 1 1 d . . . H7A H 0.3826 -0.0978 0.1651 0.045 Uiso 1 1 calc R . . H7B H 0.3598 -0.2310 0.1854 0.045 Uiso 1 1 calc R . . C8 C 0.4516(5) -0.1186(4) 0.2436(2) 0.0419(11) Uani 1 1 d . . . H8A H 0.4254 -0.1684 0.2723 0.050 Uiso 1 1 calc R . . C9 C 0.5917(5) -0.1551(5) 0.2346(2) 0.0433(12) Uani 1 1 d . . . H9A H 0.5924 -0.2408 0.2247 0.052 Uiso 1 1 calc R . . H9B H 0.6186 -0.1069 0.2061 0.052 Uiso 1 1 calc R . . C10 C -0.0026(5) 0.0323(6) 0.1839(2) 0.0521(14) Uani 1 1 d . . . H10A H -0.0364 0.1127 0.1899 0.078 Uiso 1 1 calc R . . H10B H -0.0533 -0.0276 0.2003 0.078 Uiso 1 1 calc R . . H10C H -0.0118 0.0168 0.1467 0.078 Uiso 1 1 calc R . . C11 C 0.9005(5) -0.0113(6) 0.3335(2) 0.0523(14) Uani 1 1 d . . . H11A H 0.9556 -0.0297 0.3068 0.079 Uiso 1 1 calc R . . H11B H 0.9120 -0.0739 0.3600 0.079 Uiso 1 1 calc R . . H11C H 0.9270 0.0664 0.3492 0.079 Uiso 1 1 calc R . . C12 C 0.6324(5) 0.9069(5) -0.07160(19) 0.0426(11) Uani 1 1 d . . . H12A H 0.6136 0.9684 -0.0463 0.051 Uiso 1 1 calc R . . H12B H 0.6595 0.9489 -0.1017 0.051 Uiso 1 1 calc R . . C13 C 0.7460(4) 0.8267(4) -0.04697(17) 0.0358(10) Uani 1 1 d . . . H13A H 0.7618 0.7646 -0.0730 0.043 Uiso 1 1 calc R . . C14 C 0.8715(5) 0.9014(5) -0.0352(2) 0.0449(12) Uani 1 1 d . . . H14A H 0.8929 0.9375 -0.0676 0.054 Uiso 1 1 calc R . . H14B H 0.8566 0.9675 -0.0114 0.054 Uiso 1 1 calc R . . C15 C 0.5370(5) 0.8112(5) 0.05159(18) 0.0445(12) Uani 1 1 d . . . H15A H 0.5261 0.7260 0.0609 0.053 Uiso 1 1 calc R . . H15B H 0.5190 0.8613 0.0810 0.053 Uiso 1 1 calc R . . 158 C16 C 0.6790(5) 0.8321(4) 0.04195(17) 0.0358(10) Uani 1 1 d . . . H16A H 0.6865 0.9190 0.0333 0.043 Uiso 1 1 calc R . . C17 C 0.7761(5) 0.8093(5) 0.09097(18) 0.0424(11) Uani 1 1 d . . . H17A H 0.7539 0.8624 0.1188 0.051 Uiso 1 1 calc R . . H17B H 0.7672 0.7252 0.1021 0.051 Uiso 1 1 calc R . . C18 C 0.6032(5) 0.5846(4) -0.0434(2) 0.0419(11) Uani 1 1 d . . . H18A H 0.6282 0.6058 -0.0775 0.050 Uiso 1 1 calc R . . H18B H 0.6014 0.4960 -0.0409 0.050 Uiso 1 1 calc R . . C19 C 0.7069(4) 0.6338(4) -0.00112(19) 0.0371(10) Uani 1 1 d . . . H19A H 0.6809 0.6091 0.0328 0.045 Uiso 1 1 calc R . . C20 C 0.8414(5) 0.5775(5) -0.0050(2) 0.0432(12) Uani 1 1 d . . . H20A H 0.8349 0.4892 -0.0018 0.052 Uiso 1 1 calc R . . H20B H 0.8669 0.5957 -0.0392 0.052 Uiso 1 1 calc R . . C21 C 0.2559(5) 0.7748(7) -0.0765(2) 0.0630(17) Uani 1 1 d . . . H21A H 0.2025 0.7340 -0.0535 0.095 Uiso 1 1 calc R . . H21B H 0.2449 0.7342 -0.1100 0.095 Uiso 1 1 calc R . . H21C H 0.2269 0.8585 -0.0812 0.095 Uiso 1 1 calc R . . C22 C 1.1627(5) 0.7566(5) 0.0708(2) 0.0476(12) Uani 1 1 d . . . H22A H 1.1721 0.7150 0.1041 0.071 Uiso 1 1 calc R . . H22B H 1.1960 0.8389 0.0759 0.071 Uiso 1 1 calc R . . H22C H 1.2138 0.7141 0.0474 0.071 Uiso 1 1 calc R . . loop_ _atom_site_aniso_label _atom_site_aniso_U_11 _atom_site_aniso_U_22 _atom_site_aniso_U_33 _atom_site_aniso_U_23 _atom_site_aniso_U_13 _atom_site_aniso_U_12 Si1 0.0271(6) 0.0414(7) 0.0392(7) -0.0087(5) 0.0035(5) 0.0020(5) Si2 0.0261(6) 0.0444(8) 0.0368(7) -0.0007(5) 0.0044(5) 0.0006(5) Si3 0.0289(6) 0.0531(8) 0.0378(7) -0.0038(6) 0.0018(5) 0.0083(6) Si4 0.0283(6) 0.0432(7) 0.0339(7) 0.0006(5) 0.0008(5) 0.0024(5) N1 0.0331(19) 0.0226(17) 0.0297(18) -0.0029(13) 0.0105(15) - 0.0023(13) N2 0.0331(19) 0.0299(18) 0.0274(18) 0.0008(14) 0.0065(14) 0.0065(14) O1 0.036(2) 0.070(3) 0.077(3) 0.030(2) -0.0032(19) 0.0022(18) 159 O2 0.0292(18) 0.114(4) 0.045(2) 0.000(2) 0.0096(16) - 0.001(2) O3 0.044(2) 0.053(2) 0.071(3) -0.023(2) -0.0029(18) 0.0006(17) O4 0.037(2) 0.069(3) 0.092(3) 0.031(2) 0.007(2) -0.0032(19) O5 0.036(2) 0.101(3) 0.052(2) -0.013(2) 0.0043(17) -0.008(2) O6 0.049(2) 0.063(3) 0.063(3) -0.011(2) -0.0062(18) 0.0194(19) O7 0.0379(18) 0.065(2) 0.0383(19) 0.0071(17) -0.0028(14) 0.0101(17) O8 0.0336(17) 0.069(2) 0.0412(19) -0.0058(17) 0.0054(14) 0.0152(17) O9 0.0331(18) 0.052(2) 0.060(2) -0.0044(17) 0.0012(16) - 0.0004(15) O10 0.0333(17) 0.066(2) 0.044(2) 0.0132(18) 0.0036(14) - 0.0018(17) O11 0.0399(18) 0.056(2) 0.0410(19) -0.0122(16) 0.0010(15) 0.0046(16) O12 0.0338(17) 0.0439(19) 0.052(2) -0.0022(15) -0.0049(15) 0.0119(14) C1 0.038(3) 0.032(2) 0.065(3) 0.010(2) 0.006(2) 0.009(2) C2 0.038(3) 0.042(3) 0.057(3) 0.011(2) 0.008(2) -0.001(2) C3 0.031(2) 0.037(3) 0.080(4) 0.013(3) 0.003(2) -0.003(2) C4 0.029(2) 0.061(3) 0.032(2) -0.008(2) 0.0075(18) -0.004(2) C5 0.041(3) 0.059(3) 0.045(3) -0.009(2) 0.013(2) -0.005(2) C6 0.031(2) 0.074(4) 0.028(2) -0.006(2) 0.0051(18) -0.008(2) C7 0.035(2) 0.037(2) 0.040(2) -0.0117(19) -0.0011(19) 0.0048(18) C8 0.044(3) 0.039(3) 0.042(3) -0.002(2) 0.004(2) 0.002(2) C9 0.040(3) 0.045(3) 0.043(3) -0.012(2) -0.002(2) 0.015(2) C10 0.034(3) 0.065(4) 0.056(3) -0.013(3) 0.000(2) 0.003(2) C11 0.033(3) 0.074(4) 0.050(3) -0.001(3) 0.003(2) 0.000(2) C12 0.042(3) 0.049(3) 0.036(2) 0.011(2) 0.000(2) 0.008(2) C13 0.035(2) 0.044(3) 0.028(2) 0.0033(19) 0.0052(18) 0.0037(19) C14 0.039(3) 0.052(3) 0.042(3) 0.014(2) 0.001(2) -0.003(2) C15 0.040(3) 0.064(3) 0.030(2) -0.002(2) 0.010(2) 0.015(2) C16 0.040(2) 0.037(2) 0.031(2) -0.0018(18) 0.0061(18) 0.0083(19) C17 0.037(2) 0.061(3) 0.028(2) -0.002(2) 0.0023(19) 0.007(2) C18 0.034(2) 0.035(2) 0.054(3) -0.007(2) -0.001(2) 0.0030(19) C19 0.034(2) 0.031(2) 0.044(3) -0.0030(19) 0.0016(19) 0.0029(18) C20 0.032(2) 0.042(3) 0.053(3) -0.014(2) -0.003(2) 0.010(2) C21 0.030(3) 0.095(5) 0.062(4) -0.011(3) -0.003(2) 0.013(3) C22 0.031(2) 0.060(3) 0.048(3) 0.002(2) -0.006(2) -0.002(2) _geom_special_details ; All esds (except the esd in the dihedral angle between two l.s. planes) 160 are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. ; loop_ _geom_bond_atom_site_label_1 _geom_bond_atom_site_label_2 _geom_bond_distance _geom_bond_site_symmetry_2 _geom_bond_publ_flag Si1 O1 1.594(4) . ? Si1 O2 1.629(4) . ? Si1 O3 1.644(4) . ? Si1 C10 1.829(5) . ? Si2 O4 1.619(4) . ? Si2 O6 1.624(4) . ? Si2 O5 1.627(4) . ? Si2 C11 1.826(5) . ? Si3 O9 1.630(4) . ? Si3 O8 1.631(4) . ? Si3 O7 1.638(4) . ? Si3 C21 1.829(5) . ? Si4 O12 1.626(4) . ? Si4 O10 1.628(4) . ? Si4 O11 1.631(4) . ? Si4 C22 1.833(5) . ? N1 C2 1.431(6) . ? N1 C5 1.457(6) . ? N1 C8 1.468(6) . ? N2 C16 1.453(5) . ? N2 C19 1.455(6) . ? N2 C13 1.456(5) . ? O1 C1 1.430(6) . ? O2 C4 1.396(6) . ? O3 C7 1.437(6) . ? O4 C3 1.416(6) . ? O5 C6 1.421(6) . ? O6 C9 1.432(6) . ? O7 C12 1.420(6) . ? O8 C15 1.423(6) . ? O9 C18 1.427(6) . ? O10 C14 1.423(6) . ? O11 C17 1.410(6) . ? O12 C20 1.417(6) . ? 161 C1 C2 1.529(7) . ? C2 C3 1.551(7) . ? C4 C5 1.533(7) . ? C5 C6 1.518(7) . ? C7 C8 1.535(7) . ? C8 C9 1.537(7) . ? C12 C13 1.530(6) . ? C13 C14 1.521(7) . ? C15 C16 1.524(7) . ? C16 C17 1.526(6) . ? C18 C19 1.520(6) . ? C19 C20 1.526(6) . ? loop_ _geom_angle_atom_site_label_1 _geom_angle_atom_site_label_2 _geom_angle_atom_site_label_3 _geom_angle _geom_angle_site_symmetry_1 _geom_angle_site_symmetry_3 _geom_angle_publ_flag O1 Si1 O2 112.9(2) . . ? O1 Si1 O3 114.1(2) . . ? O2 Si1 O3 109.0(2) . . ? O1 Si1 C10 107.2(3) . . ? O2 Si1 C10 106.1(2) . . ? O3 Si1 C10 107.1(2) . . ? O4 Si2 O6 111.7(2) . . ? O4 Si2 O5 111.6(3) . . ? O6 Si2 O5 109.6(2) . . ? O4 Si2 C11 107.8(2) . . ? O6 Si2 C11 108.6(2) . . ? O5 Si2 C11 107.3(2) . . ? O9 Si3 O8 110.6(2) . . ? O9 Si3 O7 111.6(2) . . ? O8 Si3 O7 111.1(2) . . ? O9 Si3 C21 107.9(3) . . ? O8 Si3 C21 107.7(2) . . ? O7 Si3 C21 107.8(3) . . ? O12 Si4 O10 111.1(2) . . ? O12 Si4 O11 112.4(2) . . ? O10 Si4 O11 112.5(2) . . ? O12 Si4 C22 106.7(2) . . ? O10 Si4 C22 106.6(2) . . ? O11 Si4 C22 107.1(2) . . ? C2 N1 C5 121.3(4) . . ? C2 N1 C8 120.3(4) . . ? C5 N1 C8 118.3(4) . . ? C16 N2 C19 119.7(4) . . ? C16 N2 C13 120.1(4) . . ? C19 N2 C13 120.1(4) . . ? C1 O1 Si1 127.6(4) . . ? 162 C4 O2 Si1 128.8(3) . . ? C7 O3 Si1 124.8(3) . . ? C3 O4 Si2 126.0(4) . . ? C6 O5 Si2 124.5(3) . . ? C9 O6 Si2 124.5(3) . . ? C12 O7 Si3 123.8(3) . . ? C15 O8 Si3 125.4(3) . . ? C18 O9 Si3 125.0(3) . . ? C14 O10 Si4 125.0(3) . . ? C17 O11 Si4 126.1(3) . . ? C20 O12 Si4 126.3(3) . . ? O1 C1 C2 111.1(4) . . ? N1 C2 C1 112.4(4) . . ? N1 C2 C3 112.6(4) . . ? C1 C2 C3 107.4(4) . . ? O4 C3 C2 110.5(4) . . ? O2 C4 C5 112.8(4) . . ? N1 C5 C6 113.1(4) . . ? N1 C5 C4 111.1(4) . . ? C6 C5 C4 109.8(4) . . ? O5 C6 C5 111.7(4) . . ? O3 C7 C8 110.6(4) . . ? N1 C8 C7 110.1(4) . . ? N1 C8 C9 111.8(4) . . ? C7 C8 C9 108.3(4) . . ? O6 C9 C8 109.9(4) . . ? O7 C12 C13 111.7(4) . . ? N2 C13 C14 112.4(4) . . ? N2 C13 C12 112.0(4) . . ? C14 C13 C12 109.3(4) . . ? O10 C14 C13 111.2(4) . . ? O8 C15 C16 111.7(4) . . ? N2 C16 C15 113.2(4) . . ? N2 C16 C17 111.9(4) . . ? C15 C16 C17 110.7(4) . . ? O11 C17 C16 111.8(4) . . ? O9 C18 C19 112.3(4) . . ? N2 C19 C18 112.5(4) . . ? N2 C19 C20 111.5(4) . . ? C18 C19 C20 110.0(4) . . ? O12 C20 C19 111.5(4) . . ? _diffrn_measured_fraction_theta_max 0.994 _diffrn_reflns_theta_full 28.30 _diffrn_measured_fraction_theta_full 0.994 _refine_diff_density_max 2.035 _refine_diff_density_min -0.475 _refine_diff_density_rms 0.134 163 APPENDIX 6 CRYSTAL STRUCTURE DATA FOR COMPOUND 36?HCl 164 dta-1 (tert-amine HCl) _audit_creation_method SHELXL-97 _chemical_name_systematic ; ? ; _chemical_name_common ? _chemical_melting_point ? _chemical_formula_moiety ? _chemical_formula_sum 'C9 H22 Cl N O6 Si0' _chemical_formula_weight 275.73 loop_ _atom_type_symbol _atom_type_description _atom_type_scat_dispersion_real _atom_type_scat_dispersion_imag _atom_type_scat_source 'C' 'C' 0.0033 0.0016 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'N' 'N' 0.0061 0.0033 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'O' 'O' 0.0106 0.0060 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'Si' 'Si' 0.0817 0.0704 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'Cl' 'Cl' 0.1484 0.1585 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'H' 'H' 0.0000 0.0000 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' _symmetry_cell_setting ? _symmetry_space_group_name_H-M ? loop_ _symmetry_equiv_pos_as_xyz 'x, y, z' '-x, -y, -z' _cell_length_a 6.8927(4) _cell_length_b 8.2335(5) _cell_length_c 11.2422(7) _cell_angle_alpha 92.2850(10) _cell_angle_beta 102.8470(10) _cell_angle_gamma 91.2820(10) _cell_volume 621.22(6) _cell_formula_units_Z 2 _cell_measurement_temperature 193(2) _cell_measurement_reflns_used ? _cell_measurement_theta_min ? _cell_measurement_theta_max ? _exptl_crystal_description ? _exptl_crystal_colour ? _exptl_crystal_size_max 0.280 _exptl_crystal_size_mid 0.278 165 _exptl_crystal_size_min 0.165 _exptl_crystal_density_meas ? _exptl_crystal_density_diffrn 1.474 _exptl_crystal_density_method 'not measured' _exptl_crystal_F_000 296 _exptl_absorpt_coefficient_mu 0.325 _exptl_absorpt_correction_type ? _exptl_absorpt_correction_T_min ? _exptl_absorpt_correction_T_max ? _exptl_absorpt_process_details ? _exptl_special_details ; ? ; _diffrn_ambient_temperature 193(2) _diffrn_radiation_wavelength 0.71073 _diffrn_radiation_type MoK\a _diffrn_radiation_source 'fine-focus sealed tube' _diffrn_radiation_monochromator graphite _diffrn_measurement_device_type ? _diffrn_measurement_method ? _diffrn_detector_area_resol_mean ? _diffrn_standards_number ? _diffrn_standards_interval_count ? _diffrn_standards_interval_time ? _diffrn_standards_decay_% ? _diffrn_reflns_number 6210 _diffrn_reflns_av_R_equivalents 0.0215 _diffrn_reflns_av_sigmaI/netI 0.0293 _diffrn_reflns_limit_h_min -9 _diffrn_reflns_limit_h_max 9 _diffrn_reflns_limit_k_min -10 _diffrn_reflns_limit_k_max 10 _diffrn_reflns_limit_l_min -14 _diffrn_reflns_limit_l_max 14 _diffrn_reflns_theta_min 1.86 _diffrn_reflns_theta_max 28.32 _reflns_number_total 3019 _reflns_number_gt 2805 _reflns_threshold_expression >2sigma(I) _computing_data_collection ? _computing_cell_refinement ? _computing_data_reduction ? _computing_structure_solution 'SHELXS-97 (Sheldrick, 1990)' _computing_structure_refinement 'SHELXL-97 (Sheldrick, 1997)' _computing_molecular_graphics ? _computing_publication_material ? _refine_special_details ; Refinement of F^2^ against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F^2^, conventional R-factors R are based on F, with F set to zero for negative F^2^. The threshold expression of F^2^ > 2sigma(F^2^) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F^2^ are statistically about twice as large as those based on F, and R- 166 factors based on ALL data will be even larger. ; _refine_ls_structure_factor_coef Fsqd _refine_ls_matrix_type full _refine_ls_weighting_scheme calc _refine_ls_weighting_details 'calc w=1/[\s^2^(Fo^2^)+(0.0499P)^2^+0.0984P] where P=(Fo^2^+2Fc^2^)/3' _atom_sites_solution_primary direct _atom_sites_solution_secondary difmap _atom_sites_solution_hydrogens geom _refine_ls_hydrogen_treatment mixed _refine_ls_extinction_method SHELXL _refine_ls_extinction_coef 0.079(7) _refine_ls_extinction_expression 'Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^' _refine_ls_number_reflns 3019 _refine_ls_number_parameters 243 _refine_ls_number_restraints 0 _refine_ls_R_factor_all 0.0313 _refine_ls_R_factor_gt 0.0297 _refine_ls_wR_factor_ref 0.0842 _refine_ls_wR_factor_gt 0.0831 _refine_ls_goodness_of_fit_ref 1.068 _refine_ls_restrained_S_all 1.068 _refine_ls_shift/su_max 0.004 _refine_ls_shift/su_mean 0.001 loop_ _atom_site_label _atom_site_type_symbol _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_U_iso_or_equiv _atom_site_adp_type _atom_site_occupancy _atom_site_symmetry_multiplicity _atom_site_calc_flag _atom_site_refinement_flags _atom_site_disorder_assembly _atom_site_disorder_group Cl1 Cl 0.50100(4) 0.61215(3) 0.81232(2) 0.02694(11) Uani 1 1 d . . . O3 O 0.16907(12) 0.17535(9) 1.00167(7) 0.02465(18) Uani 1 1 d . . . O6 O -0.46385(11) 0.23196(11) 0.56263(8) 0.02730(18) Uani 1 1 d . . . O5 O -0.36887(10) -0.10950(9) 0.67299(7) 0.02287(17) Uani 1 1 d . . . O4 O -0.44110(11) 0.23670(11) 0.85110(8) 0.02757(19) Uani 1 1 d . . . N1 N -0.12595(12) 0.17035(9) 0.73757(7) 0.01493(17) Uani 1 1 d . . . O2 O 0.06068(12) 0.51167(9) 0.68675(7) 0.02457(18) Uani 1 1 d . . . O1 O 0.21374(12) -0.00145(10) 0.63643(7) 0.02525(18) Uani 1 1 d . . . C9 C -0.03559(14) 0.00343(11) 0.75922(8) 0.01628(19) Uani 1 1 d . . . C8 C -0.09609(14) 0.28573(11) 0.85029(8) 0.01631(19) Uani 1 1 d . . . C7 C -0.10335(14) 0.24943(12) 0.62035(8) 0.01748(19) Uani 1 1 d . . . C6 C 0.11417(14) 0.30835(12) 0.92611(9) 0.0189(2) Uani 1 1 d . . . C5 C 0.18339(14) -0.00913(12) 0.75760(9) 0.0200(2) Uani 1 1 d . . . C4 C -0.16324(14) -0.12016(12) 0.66876(9) 0.0201(2) Uani 1 1 d . . . C3 C 0.08093(15) 0.35770(12) 0.62932(9) 0.0203(2) Uani 1 1 d . . . C2 C -0.24513(15) 0.23409(12) 0.92470(9) 0.0204(2) Uani 1 1 d . . . C1 C -0.29538(15) 0.33850(13) 0.57124(10) 0.0230(2) Uani 1 1 d . . . H81 H -0.1305(18) 0.3884(16) 0.8199(11) 0.015(3) Uiso 1 1 d . . . H11 H -0.309(2) 0.4276(18) 0.6270(13) 0.025(3) Uiso 1 1 d . . . H91 H -0.0506(17) -0.0190(14) 0.8366(11) 0.012(3) Uiso 1 1 d . . . H71 H -0.0960(19) 0.1609(16) 0.5639(12) 0.019(3) Uiso 1 1 d . . . 167 H21 H -0.228(2) 0.3043(17) 0.9953(13) 0.026(3) Uiso 1 1 d . . . H62 H 0.211(2) 0.3211(16) 0.8748(13) 0.026(3) Uiso 1 1 d . . . H32 H 0.200(2) 0.3086(17) 0.6724(12) 0.026(3) Uiso 1 1 d . . . H42 H -0.1180(19) -0.2238(17) 0.6897(12) 0.020(3) Uiso 1 1 d . . . H71 H 0.092(2) 0.3724(17) 0.5434(13) 0.027(3) Uiso 1 1 d . . . H1 H -0.257(2) 0.1446(17) 0.7215(12) 0.022(3) Uiso 1 1 d . . . H61 H 0.113(2) 0.4085(16) 0.9768(12) 0.021(3) Uiso 1 1 d . . . H41 H -0.155(2) -0.1014(16) 0.5864(12) 0.022(3) Uiso 1 1 d . . . H22 H -0.2252(19) 0.1265(17) 0.9487(12) 0.019(3) Uiso 1 1 d . . . H52 H 0.265(2) 0.0719(17) 0.8119(13) 0.027(3) Uiso 1 1 d . . . H51 H 0.218(2) -0.1138(18) 0.7879(13) 0.026(3) Uiso 1 1 d . . . H12 H -0.289(2) 0.3786(18) 0.4915(13) 0.029(3) Uiso 1 1 d . . . H6' H -0.496(2) 0.1937(19) 0.4931(16) 0.035(4) Uiso 1 1 d . . . H3' H 0.268(3) 0.203(2) 1.0470(16) 0.038(4) Uiso 1 1 d . . . H5' H -0.393(3) -0.185(2) 0.7160(16) 0.046(5) Uiso 1 1 d . . . H1' H 0.332(3) 0.020(2) 0.6446(15) 0.043(4) Uiso 1 1 d . . . H2' H 0.171(3) 0.546(2) 0.7132(17) 0.051(5) Uiso 1 1 d . . . H4' H -0.463(3) 0.331(2) 0.8397(16) 0.047(5) Uiso 1 1 d . . . loop_ _atom_site_aniso_label _atom_site_aniso_U_11 _atom_site_aniso_U_22 _atom_site_aniso_U_33 _atom_site_aniso_U_23 _atom_site_aniso_U_13 _atom_site_aniso_U_12 Cl1 0.02280(15) 0.02405(15) 0.03115(16) 0.00152(10) 0.00037(10) - 0.00305(10) O3 0.0229(4) 0.0254(4) 0.0218(4) 0.0040(3) -0.0034(3) -0.0037(3) O6 0.0178(4) 0.0384(4) 0.0232(4) 0.0027(3) -0.0006(3) -0.0043(3) O5 0.0166(3) 0.0217(4) 0.0294(4) 0.0014(3) 0.0038(3) -0.0038(3) O4 0.0161(4) 0.0266(4) 0.0407(5) 0.0013(3) 0.0081(3) -0.0016(3) N1 0.0128(4) 0.0154(4) 0.0162(4) -0.0005(3) 0.0028(3) -0.0010(3) O2 0.0209(4) 0.0183(3) 0.0332(4) -0.0009(3) 0.0041(3) -0.0029(3) O1 0.0174(4) 0.0343(4) 0.0248(4) -0.0026(3) 0.0069(3) 0.0013(3) C9 0.0161(4) 0.0143(4) 0.0180(4) 0.0002(3) 0.0032(3) -0.0002(3) C8 0.0164(4) 0.0152(4) 0.0174(4) -0.0019(3) 0.0044(3) -0.0010(3) C7 0.0171(4) 0.0190(4) 0.0160(4) 0.0013(3) 0.0029(3) -0.0005(3) C6 0.0179(4) 0.0175(4) 0.0199(4) -0.0013(3) 0.0019(4) -0.0024(3) C5 0.0160(4) 0.0205(5) 0.0223(5) -0.0009(4) 0.0018(3) 0.0018(3) C4 0.0171(4) 0.0177(4) 0.0247(5) -0.0038(4) 0.0041(4) -0.0019(3) C3 0.0191(5) 0.0199(5) 0.0224(5) 0.0020(4) 0.0060(4) -0.0011(4) C2 0.0193(5) 0.0204(5) 0.0231(5) -0.0017(4) 0.0088(4) -0.0016(4) C1 0.0184(5) 0.0251(5) 0.0233(5) 0.0046(4) -0.0005(4) 0.0005(4) _geom_special_details ; All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. ; loop_ _geom_bond_atom_site_label_1 168 _geom_bond_atom_site_label_2 _geom_bond_distance _geom_bond_site_symmetry_2 _geom_bond_publ_flag O3 C6 1.4191(12) . ? O3 H3' 0.779(18) . ? O6 C1 1.4230(13) . ? O6 H6' 0.812(17) . ? O5 C4 1.4332(12) . ? O5 H5' 0.838(19) . ? O4 C2 1.4196(13) . ? O4 H4' 0.802(19) . ? N1 C8 1.5264(12) . ? N1 C9 1.5276(11) . ? N1 C7 1.5297(12) . ? N1 H1 0.903(14) . ? O2 C3 1.4234(12) . ? O2 H2' 0.79(2) . ? O1 C5 1.4270(12) . ? O1 H1' 0.815(19) . ? C9 C5 1.5193(13) . ? C9 C4 1.5243(13) . ? C9 H91 0.924(12) . ? C8 C6 1.5125(13) . ? C8 C2 1.5254(13) . ? C8 H81 0.940(13) . ? C7 C3 1.5177(13) . ? C7 C1 1.5314(13) . ? C7 H71 0.957(13) . ? C6 H62 0.978(14) . ? C6 H61 0.984(13) . ? C5 H52 0.965(14) . ? C5 H51 0.955(14) . ? C4 H42 0.936(14) . ? C4 H41 0.958(14) . ? C3 H32 0.962(14) . ? C3 H71 0.997(14) . ? C2 H21 0.947(14) . ? C2 H22 0.941(14) . ? C1 H11 0.966(14) . ? C1 H12 0.978(15) . ? loop_ _geom_angle_atom_site_label_1 _geom_angle_atom_site_label_2 _geom_angle_atom_site_label_3 _geom_angle _geom_angle_site_symmetry_1 _geom_angle_site_symmetry_3 _geom_angle_publ_flag C6 O3 H3' 105.7(12) . . ? C1 O6 H6' 108.2(11) . . ? C4 O5 H5' 106.4(12) . . ? C2 O4 H4' 105.6(13) . . ? C8 N1 C9 115.46(7) . . ? C8 N1 C7 115.15(7) . . ? C9 N1 C7 116.08(7) . . ? C8 N1 H1 103.2(8) . . ? C9 N1 H1 101.6(9) . . ? C7 N1 H1 102.2(8) . . ? C3 O2 H2' 105.6(13) . . ? C5 O1 H1' 105.3(12) . . ? C5 C9 C4 111.24(8) . . ? 169 C5 C9 N1 116.80(8) . . ? C4 C9 N1 108.34(7) . . ? C5 C9 H91 108.1(7) . . ? C4 C9 H91 108.1(7) . . ? N1 C9 H91 103.7(7) . . ? C6 C8 C2 113.05(8) . . ? C6 C8 N1 116.63(8) . . ? C2 C8 N1 107.74(7) . . ? C6 C8 H81 105.3(8) . . ? C2 C8 H81 108.4(8) . . ? N1 C8 H81 105.2(7) . . ? C3 C7 N1 116.52(8) . . ? C3 C7 C1 112.12(8) . . ? N1 C7 C1 107.38(8) . . ? C3 C7 H71 107.1(8) . . ? N1 C7 H71 105.3(8) . . ? C1 C7 H71 108.0(8) . . ? O3 C6 C8 111.54(8) . . ? O3 C6 H62 108.7(8) . . ? C8 C6 H62 111.6(8) . . ? O3 C6 H61 110.0(8) . . ? C8 C6 H61 105.2(8) . . ? H62 C6 H61 109.8(11) . . ? O1 C5 C9 111.22(8) . . ? O1 C5 H52 111.2(9) . . ? C9 C5 H52 111.9(8) . . ? O1 C5 H51 109.5(8) . . ? C9 C5 H51 104.4(8) . . ? H52 C5 H51 108.2(12) . . ? O5 C4 C9 110.73(8) . . ? O5 C4 H42 110.1(8) . . ? C9 C4 H42 107.8(8) . . ? O5 C4 H41 106.7(8) . . ? C9 C4 H41 111.7(8) . . ? H42 C4 H41 109.8(11) . . ? O2 C3 C7 111.09(8) . . ? O2 C3 H32 109.4(8) . . ? C7 C3 H32 112.4(8) . . ? O2 C3 H71 109.7(8) . . ? C7 C3 H71 105.6(8) . . ? H32 C3 H71 108.5(11) . . ? O4 C2 C8 109.46(8) . . ? O4 C2 H21 112.3(8) . . ? C8 C2 H21 108.7(8) . . ? O4 C2 H22 106.4(8) . . ? C8 C2 H22 110.9(8) . . ? H21 C2 H22 109.1(12) . . ? O6 C1 C7 110.21(8) . . ? O6 C1 H11 106.7(8) . . ? C7 C1 H11 110.1(8) . . ? O6 C1 H12 111.3(8) . . ? C7 C1 H12 108.0(8) . . ? H11 C1 H12 110.5(12) . . ? _diffrn_measured_fraction_theta_max 0.978 _diffrn_reflns_theta_full 28.32 _diffrn_measured_fraction_theta_full 0.978 _refine_diff_density_max 0.379 _refine_diff_density_min -0.219 _refine_diff_density_rms 0.051 tertiary amine HCl 1 170