HYDROTHERMAL SYNTHESIS AND CHARACTERIZATION OF NOVEL 
THORIUM, URANIUM, AND NEPTUNIUM SOLIDS 
 
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. 
 
 
 
????????????????????????????????? 
Tyler Andrew Sullens 
 
 
Certificate of Approval: 
 
 
 
??????????????????????????????  ?????????????????????????????? 
Thomas E. Albrecht-Schmitt, Chair   Thomas R. Webb 
Associate Professor     Associate Professor 
Chemistry      Chemistry 
 
 
 
??????????????????????????????  ?????????????????????????????? 
Holly R. Ellis      Curtis G. Shannon 
Assistant Professor     Associate Professor 
Chemistry      Chemistry 
 
 
 
        ?????????????????????????????? 
        Stephen L. McFarland 
        Acting Dean 
        Graduate School 
 
HYDROTHERMAL SYNTHESIS AND CHARACTERIZATION OF NOVEL  
 
 
THORIUM, URANIUM, AND NEPTUNIUM SOLIDS 
 
 
Tyler Andrew Sullens 
 
 
 
 
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 
 
August 8, 2005 
- iii - 
HYDROTHERMAL SYNTHESIS AND CHARACTERIZATION OF NOVEL  
 
 
THORIUM, URANIUM, AND NEPTUNIUM SOLIDS 
 
 
 
 
Tyler Andrew Sullens 
 
 
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 
 
Tyler Andrew Sullens, son of Terry H. Sullens and Gloria J. (Spikes) Sullens, was 
born on November 23, 1978, in Birmingham, Alabama.  He graduated from John Carroll 
High School in Birmingham, Alabama, in 1997.  He then attended the University of 
Alabama at Birmingham for two years before transferring to the University of 
Montevallo, where he graduated in May of 2001 with a Bachelor of Science degree in 
Chemistry under the direction of Dr. Houston Byrd and Dr. Prakash Bharara.  He then 
entered Auburn University in the fall of 2001 to pursue a Doctoral degree in Inorganic 
Chemistry under the tutelage of Dr. Thomas E. Albrecht-Schmitt.  
- v - 
DISSERTATION ABSTRACT 
HYDROTHERMAL SYNTHESIS AND CHARACTERIZATION OF NOVEL 
THORIUM, URANIUM, AND NEPTUNIUM SOLIDS 
 
Tyler A. Sullens 
Doctor of Philosophy, August 8, 2005 
(B. S., University of Montevallo, 2001) 
 
 
203 Typed Pages 
 
Directed by Thomas E. Albrecht-Schmitt 
 
 Hydrothermal synthesis has been utilized to synthesize several compounds 
involving thorium, uranium, and neptunium.  These compounds have one-, two-, and 
three-dimensional structural typologies.  A majority of the compounds reported are 
strictly inorganic in composition; however, some examples of solids with the 
incorporation of organic molecules are reported.  The compounds reported consist of 
thorium(IV) selenites, selenates, chromates, tellurates, and iodates, uranium(VI) 
periodates, transition metal uranium(IV) fluorides, and neptunium(IV) fluorides.  The 
structural characteristics of these molecules augment the knowledge base of the chemical 
complexity of these early actinide elements.  All structures were delineated through the 
use of single crystal X-ray diffraction with the aid of EDAX and IR analysis.  Structure
- vi - 
properties of the synthetic phases were examined as necessary.  These structural aspects 
include second-harmonic generation of light and ion exchange.  Examples of open-
framework and channel structures are also reported. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
- vii - 
ACKNOWLEDGEMENT 
 
Although there are many people that I feel that I need to thank for their help 
during this work, I wish to first thank the Department of Energy, Heavy Elements 
Program, for providing the funding for this research.  I could not have imagined working 
for a better, more understanding, or friendlier person than Thomas Albrecht-Schmitt.  
This entire process could have been excruciating without him.  I wish to thank my parents 
for their love and support throughout all of this.  The friends that I have made here, 
especially Phil, Akin, Henry, Robert, and Rodney, have made my years at Auburn 
bearable, with a few nights in there that were way too much fun, mostly at the Buffalo?s 
and the Sup(p)er Club.   
But, I think above all, the person I need to thank the most is Lane Simmons.  He 
has stuck beside me through all of this and more.  We grew up together.  He?s the best 
friend anyone can have.  He has a fine, steady hand.  Although everyone else that we?ve 
known has fallen to the way side, we have always managed to stay together, whether 
we?ve deserved it or not.  We?ve managed to survive The Dark Days, Wyoming, New 
Orleans, Ivan, Bushmills, ex?s, bears, boulders, cliffs, and the occasional catapult.  I think 
that getting this far without his support would have been nearly impossible.  I can?t thank 
him enough.  I would hope to think that he would tell me ?Way to go, Donny!?  Skulnick.
- viii - 
Style manual or journal used: 
American Chemical Society style 
 
Computer software used: 
Microsoft Word 2000, Microsoft Excel, Atoms v.5.0, CorelDRAW 10 
- ix - 
TABLE OF CONTENTS 
 
CHAPTER 1.  INTRODUCTION............................................................................     1 
 RESEARCH GOALS...............................................................................     1 
 HYDROTHERMAL SYNTHESIS..........................................................     2 
 THE ACTINIDES....................................................................................     5 
 ORGANIC TEMPLATING.....................................................................   14 
 STRUCTURE-PROPERTY RELATIONSHIPS.....................................   16 
 DESIRED ANIONS.................................................................................   18 
 REFERENCES.........................................................................................   29 
 
CHAPTER 2.  HYDROTHERMAL SYNTHESIS OF THE FIRST  
ORGANICALLY TEMPLATED NEPTUNIUM FLUORIDES.................................   34 
 ABSTRACT................................................................................................   34
 INTRODUCTION......................................................................................   35
 EXPERIMENTAL.....................................................................................   36 
  SYNTHESIS OF (C H N )Np F
2 10 2 2 10
............................................   37
  SYNTHESIS OF (C
4
H
12
N
2
)
2
Np
2
F
12
?H
2
O..................................   37 
  CRYSTALLOGRAPHIC STUDIES..........................................   37
- x - 
 RESULTS AND DISCUSSION................................................................   38
  STRUCTURE OF (C H N )Np F
2 10 2 2 10
..........................................   38
  STRUCTURE OF (C
4
H
12
N
2
)
2
Np
2
F
12
?H
2
O.................................   39 
 REFERENCES...........................................................................................   52 
 
CHAPTER 3.  HYDROTHERMAL PREPARATION OF NI(II)/U(IV)  
FLUORIDES WITH ONE-, TWO-, AND THREE-DIMENSIONAL  
TOPOLOGIES..............................................................................................................   55 
 ABSTRACT................................................................................................   56 
 INTRODUCTION......................................................................................   58 
 EXPERIMENTAL......................................................................................   58 
  SYNTHESIS OF Ni(H
2
O)
4
UF
6
?1.5H
2
O AND  
  Ni(H
2
O)
2
UF
6
(H
2
O)......................................................................   58 
  SYNTHESIS OF Ni
2
(H
2
O)
6
U
3
F
16
?3H
2
O.....................................   59 
  CRYSTALLOGRAPHIC STUDIES...........................................   59 
 RESULTS AND DISCUSSION.................................................................   60 
  SYNTHESES...............................................................................   60 
  STRUCTURE OF Ni(H
2
O)
4
UF
6
?1.5H
2
O....................................   61 
  STRUCTURE OF Ni
2
(H
2
O)
6
U
3
F
16
?3H
2
O...................................   64 
  STRUCTURE OF Ni(H
2
O)
2
UF
6
(H
2
O)........................................   67 
 CONCLUSIONS.........................................................................................   72 
 REFERENCES............................................................................................   80 
   
- xi - 
CHAPTER 4.  STRUCTURE AND PROPERTIES OF THE THORIUM  
VANADYL TELLURATE, Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
...................................................   84 
 ABSTRACT................................................................................................   84 
 INTRODUCTION......................................................................................   85 
 EXPERIMENTAL......................................................................................   86 
  SYNTHESIS OF Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
...................................   86 
  THERMAL ANALYSIS..............................................................  87 
  UV-VIS DIFFUSE REFLECTANCE SPECTRA.......................   87 
  X-RAY POWDER DIFFRACTION DATA...............................   87 
  CRYSTALLOGRAPHIC STUDIES...........................................   87 
 RESULTS AND DISCUSSION.................................................................   88 
  SYNTHESIS OF Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
...................................   88 
  STRUCTURE OF Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
.................................   90
  OPTICAL PROPERTIES............................................................   95 
  THERMAL BEHAVIOR............................................................. 100 
 CONCLUSIONS......................................................................................... 100 
 REFERENCES............................................................................................ 103 
 
CHAPTER 5.  CATION-CATION INTERACTIONS BETWEEN URANYL  
CATIONS IN A POLAR OPEN-FRAMEWORK URANYL PERIODATE.............. 105 
 ABSTRACT................................................................................................ 105 
 INTRODUCTION...................................................................................... 105 
 EXPERIMENTAL...................................................................................... 106 
- xii - 
  SYNTHESIS OF Li[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O....... 107 
  SYNTHESIS OF Na[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O....... 107 
  SYNTHESIS OF K[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O........ 107 
  SYNTHESIS OF Rb[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O....... 107 
  SYNTHESIS OF Cs[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O....... 108 
  SYNTHESIS OF Ag[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O...... 108 
  X-RAY STRUCTURE ANALYSIS............................................ 109 
  ION-EXCHANGE ANALYSIS.................................................. 111 
 RESULTS AND DISCUSSION................................................................. 112 
  SYNTHESIS................................................................................ 112 
  STRUCTURE OF Cs[(UO
2
)
3
(HIO
6
)
2
(OH)(O)(H
2
O)]?1.5H
2
O.... 112 
  ION-EXCHANGE....................................................................... 124 
 REFERENCES............................................................................................ 128 
 
CHAPTER 6.  EXTENDED NETWORKS, POROUS SHEETS, AND CHIRAL 
FRAMEWORKS.  THORIUM MATERIALS CONTAINING MIXED  
GEOMETRY ANIONS: STRUCTURES AND PROPERTIES OF  
Th(SeO
3
)(SeO
4
), Th(IO
3
)
2
(SeO
4
)(H
2
O)
3
?H
2
O, and Th(CrO
4
)(IO
3
)
2
............................. 130
 ABSTRACT................................................................................................ 130 
 INTRODUCTION...................................................................................... 131 
 EXPERIMENTAL...................................................................................... 132 
  SYNTHESIS OF Th(SeO
3
)(SeO
4
)............................................... 133 
  SYNTHESIS OF Th(IO
3
)
2
(SeO
4
)(H
2
O)
3
?H
2
O............................. 133 
- xiii - 
  SYNTHESIS OF Th(CrO
4
)(IO
3
)
2
................................................ 134
  NONLINEAR OPTICAL MEASUREMENTS........................... 134 
  CRYSTALLOGRAPHIC STUDIES........................................... 134 
 RESULTS AND DISCUSSION................................................................. 135 
  SYNTHESES............................................................................... 135 
  STRUCTURE OF Th(SeO
3
)(SeO
4
)............................................. 137 
  STRUCTURE OF Th(IO
3
)
2
(SeO
4
)(H
2
O)
3
?H
2
O........................... 141 
  STRUCTURE OF Th(CrO
4
)(IO
3
)
2
.............................................. 145
 CONCLUSIONS......................................................................................... 148 
 REFERENCES............................................................................................ 153 
 
CHAPTER 7.  SYNTHESIS AND CHARACTERIZATION OF THORIUM 
IN NOVEL THREE-DIMENSIONAL TOPOLOGIES: Th
2
(CrO
4
)
4
(H
2
O)
2
  
AND Th(SeO
3
)
2
............................................................................................................ 156 
 ABSTRACT................................................................................................ 156 
 INTRODUCTION...................................................................................... 157 
 EXPERIMENTAL...................................................................................... 159 
  SYNTHESIS OF Th
2
(CrO
4
)
4
(H
2
O)
2
............................................ 159
  SYNTHESIS OF Th(SeO
3
)
4
........................................................ 159 
  CRYSTALLOGRAPHIC STUDIES........................................... 160 
 RESULTS AND DISCUSSION................................................................. 161 
  SYNTHESES............................................................................... 161 
  STRUCTURE OF Th
2
(CrO
4
)
4
(H
2
O)
2
.......................................... 163 
- xiv - 
  STRUCTURE OF Th(SeO
3
)
2
....................................................... 172
 CONCLUSION........................................................................................... 177 
 REFERENCES............................................................................................ 181
 
 
 
 
 
 
 
 
 
 
LIST OF FIGURES 
 
Figure 1.1.  A diagram of a PARR 4749 autoclave.....................................................     4 
Figure 1.2.  A compositional diagram of UO
3
, HF, and homopiperazine...................     6 
Figure 1.3.  The UO
2
2+
 uranyl unit exists as a nearly linear trans dioxo unit..............     9 
Figure 1.4.  A depiction of the types of bonding in which the AnO
2
[X
5
]  
 pentagonal bipyramid participates...........................................................   11 
Figure 1.5.  An example of a cation-cation interaction (CCI) in a sheet typology......   13 
Figure 1.6.  A view down the b axis of the two-dimensional  
 [C
5
H
14
N
2
][U
2
F
10
(H
2
O)]............................................................................  15 
Figure 1.7.  A depiction of a channels in the three-dimensional  
   [UO
3
?
2
Ga(PO
4
)
2
]
1-
 framework of Cs[UO
2
Ga(PO
4
)
2
]............................   17 
Figure 1.8.  A projection of the structure of Hg(IO
3
)
2
.................................................
 
  20 
Figure 1.9.  A depiction of the crystal structure of Au
2
(SeO
3
)
2
(SeO
4
)........................   21 
Figure 1.10.  A depiction of the IO
4
3-
 anion.................................................................   22 
Figure 1.11.  This depiction of Pb(UO
2
)(SeO
3
)
2
..........................................................   23 
Figure 1.12.  A depiction of a symmetric periodate (IO
6
5-
) anion...............................   24 
Figure 1.13.  The thermal ellipsoid of Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
...................................   25 
Figure 1.14.  A depiction of K
2
[(UO
2
)
2
(VO)
2
(IO
6
)
2
O]?H
2
O........................................   27 
Figure 1.15.  A second view of K
2
[(UO
2
)
2
(VO)
2
(IO
6
)
2
O]?H
2
O...................................   28
- xv - 
Figure 2.1.  Thermal ellipsoid plot of (C
2
H
10
N
2
)Np
2
F
10
..............................................   40 
Figure 2.2.  A view down the a-axis depicting the [Np F ]  sheets..........................   41
2 10
2-
Figure 2.3.  A view of (C
2
H
10
N
2
)Np
2
F
10
 down the b-axis...........................................   42 
Figure 2.4.  Thermal ellipsoid plot of (C
4
H
12
N
2
)
2
Np
2
F
12
?H
2
O....................................   44 
Figure 2.5.  The one-dimensional neptunium fluoride chains that form in 
(C
4
H
12
N
2
)
2
Np
2
F
12
?H
2
O............................................................................   45
Figure 2.6.  A view down the c-axis showing neptunium fluoride chains              
separated by the piperazinium dications..................................................   49 
Figure 3.1.  The chains of edge-sharing dodecahedral [UF
8
] that forms                            
in Ni(H
2
O)
4
UF
6
?2.5H
2
O (1).....................................................................   62 
Figure 3.2.  A view of the channel structure of Ni(H
2
O)
4
UF
6
?2.5H
2
O........................   65 
Figure 3.3.  A depiction of the cyclic trimer formed from the edge-sharing                      
of three [UF
9
] in Ni
2
(H
2
O)
6
U
3
F
16
?3H
2
O.................................................    68 
Figure 3.4.  A representation of the two-dimensional [U
2
?
3
F
16
]
4?
 sheets in 
Ni
2
(H
2
O)
6
U
3
F
16
?3H
2
O..............................................................................   69 
Figure 3.5.  A view down the c-axis showing the capping of a [U
2
?
3
F
16
]
4?
                  
sheet with fac-[Ni(H
2
O)
3
F
3
] octahedra....................................................   70 
Figure 3.6.  The [UF
8
(H
2
O)] tricapped trigonal prisms in Ni(H
2
O)
2
UF
6
(H
2
O)..........    73 
Figure 3.7.  A view down the c-axis of the three-dimensional network structure              
of Ni(H
2
O)
2
UF
6
(H
2
O) (3)........................................................................   74 
Figure 4.1.  A thermal ellipsoid plot of Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
.................................   91 
Figure 4.2.  a) A depiction of the interactions between the VO
5
 distorted square  
pyramids and neighboring polyhedra in Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
............   94 
- xvi - 
- xvii - 
Figure 4.2.  b) The VO
4
 units corner-share with two ThO
9
 units and two TeO
6
           
units..........................................................................................................   94 
Figure 4.3.  An illustration of the bonding for the tellurate, TeO
6
6?
, anion in 
Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
............................................................................   96 
Figure 4.4.  A view of the ThO
9
, VO
5
, and TeO
6
 units that form a continuum of         
edge-sharing interactions to yield Th-V-Te oxide chains that extends     
along the b-axis........................................................................................   97 
Figure 4.5.  The three-dimensional network of Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
.....................   98 
Figure 4.6.  The diffuse reflectance absorbance spectrum of  
 Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
............................................................................   99 
Figure 4.7.  Thermogravimetric analysis of Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
.......................... 101 
Figure 5.1.  Thermal ellipsoid plot of Cs[(UO
2
)
3
(HIO
6
)
2
(OH)(O)(H
2
O)]?1.5H
2
O             
at 50% probability.................................................................................... 117 
Figure 5.2.  A view down the c axis showing the polar open-framework structures         
of A[(UO ) (HIO )(OH)(O)(H O)]?1.5H O (Li(1)-Cs(5))...................... 118 
2 3 6 2 2
Figure 5.3.  An illustration of the cation-cation interaction between the uranyl             
unit containing U(3) and the uranyl cation containing U(1).................... 119 
Figure 5.4. A view of A[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (Li(1)-Cs(5))        
showing the second type of channel........................................................ 121 
Figure 5.5.  The differences in location of the counter cation between                                
the analogues of A[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O                           
(A = Li(1)?Cs(5), Ag(6))......................................................................... 123 
Figure 6.1.  A thermal ellipsoid plot of Th(SeO
3
)(SeO
4
) (1)....................................... 138 
Figure 6.2.  A depiction of the extended structure of Th(SeO
3
)(SeO
4
) (1).................. 139 
Figure 6.3.  A thermal ellipsoid plot of Th(IO
3
)
2
(SeO
4
)(H
2
O)
3
?H
2
O (2)..................... 142 
Figure 6.4.  A view down [111] of Th(IO
3
)
2
(SeO
4
)(H
2
O)
3
?H
2
O (2)............................ 143 
Figure 6.5.  A thermal ellipsoid plot of Th(CrO
4
)(IO
3
)
2
 (3)........................................ 146 
Figure 6.6.  An illustration of the extended structure of Th(CrO
4
)(IO
3
)
2
 (3).............. 149 
Figure 7.1.  Thermal ellipsoid plot of Th
2
(CrO
4
)
4
(H
2
O)
2
............................................ 164 
Figure 7.2.  A view of Th
2
(CrO
4
)
4
(H
2
O)
2
 down the a-axis showing the                  
bridging individual layers that are formed............................................... 165 
Figure 7.3.  The a/b plane shows the [ Th(CrO)(CrO
2
?
2
)
3
(H
2
O)] sheet...................... 169 
Figure 7.4.  Another view of the a/b plain showing the second thorium chromate       
sheet......................................................................................................... 170 
Figure 7.5.  Figure 1 shown with Th(2)O
9
 as a polyhedron and Th(1)O
8
 as the              
bare moiety...............................................................................................171 
Figure 7.6.  Thermal ellipsoid plot of the asymmetric unit of Th(SeO
3
)
2
 at                  
50% probability........................................................................................ 173 
Figure 7.7.  A view down the a-axis of Th(SeO
3
)
2
 showing an area between                     
four thorium oxide chains formed by the opposing polarities                        
of two selenite anions...............................................................................174 
Figure 7.8.  An expanded view down the a-axis showing the entirety of the          
Th(SeO
3
)
2 
................................................................................................ 175 
Figure 7.9.  This view down the c-axis demonstrates the edge sharing that  
 occurs within the Th(SeO
3
)
2
 structure..................................................... 176
- xviii - 
- xix - 
LIST OF TABLES 
 
Table 1.1.  The oxidation states of the early actinide series.........................................     7 
Table 1.2.  The ground-state electron configuration of the lanthanides  
 and the actinides........................................................................................     8
Table 2.1.  Crystallographic Data for (C
2
H
10
N
2
)Np
2
F
10
 (1) and  
 (C
4
H
12
N
2
)
2
Np
2
F
12
?H
2
O (2)........................................................................   43 
Table 2.2. Selected Bond Distances (?) and Angles (?) for (C
2
H
10
N
2
)Np
2
F
10
............   46 
Table 2.3. Selected Bond Distances (?) for and Angles (?) (C
4
H
12
N
2
)
2
Np
2
F
12
?H
2
O...   47 
Table 2.4.  Atomic Coordinates and Equivalent Isotropic Displacement  
 Parameters for (C
2
H
10
N
2
)Np
2
F
10
 (1).........................................................   50 
Table 2.5.  Atomic Coordinates and Equivalent Isotropic Displacement  
 Parameters for (C
4
H
12
N
2
)
2
Np
2
F
12
?H
2
O (2)................................................   51 
Table 3.1.  Crystallographic data for Ni(H
2
O)
4
UF
6
?2.5H
2
O (1),  
 Ni
2
(H
2
O)
6
U
3
F
16
?3H
2
O (2), and Ni(H
2
O)
2
UF
6
(H
2
O) (3)............................   63 
Table 3.2.  Selected Bond Distances (?) for Ni(H
2
O)
4
UF
6
?2.5H
2
O (1).......................   66 
Table 3.3.  Selected Bond Distances (?) for Ni
2
(H
2
O)
6
U
3
F
16
?3H
2
O (2)......................   71 
Table 3.4.  Selected Bond Distances (?) for Ni(H
2
O)
2
UF
6
(H
2
O) (3)..........................   75 
Table 3.5.  Atomic Coordinates and Equivalent Isotropic Displacement   
 Parameters for Ni(H
2
O)
4
UF
6
?2.5H
2
O (1)..................................................   77 
- xx - 
Table 3.6.  Atomic Coordinates and Equivalent Isotropic Displacement  
 Parameters for Ni
2
(H
2
O)
6
U
3
F
16
?3H
2
O (2).................................................   78 
Table 3.7.  Atomic Coordinates and Equivalent Isotropic Displacement  
 Parameters for Ni(H
2
O)
2
UF
6
(H
2
O) (3)......................................................   79 
Table 4.1.  Crystallographic Data for Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
....................................   89 
Table 4.2.  Selected Bond Distances (?) and Angles (
o
) for  
 Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
.............................................................................   92 
Table 4.3.  Atomic Coordinates and Equivalent Isotropic Displacement  
 Parameters for Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
..................................................... 102 
Table 5.1.  Crystallographic data for A[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O  
 (A = Li(1), Na(2))...................................................................................... 113 
Table 5.2.  Crystallographic data for A[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O  
 (A = K(3), Rb(4))...................................................................................... 114  
Table 5.3.  Crystallographic data for A[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O  
 (A = Cs(5), Ag(6))..................................................................................... 115 
Table 5.4.  Ion-exchange studies of the various analogues of 1-5............................... 125 
Table 5.5.  Atomic Coordinates and Equivalent Isotropic Displacement  
 Parameters for Cs[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (5)................... 126 
Table 5.6.  Atomic Coordinates and Equivalent Isotropic Displacement  
 Parameters for Ag[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (6).................. 127 
Table 6.1.  Crystallographic Data for Th(SeO
3
)(SeO
4
) (1),  
 Th(IO
3
)
2
(SeO
4
)(H
2
O)
3
?H
2
O (2), and Th(CrO
4
)(IO
3
)
2
 (3).......................... 136 
Table 6.2.  Selected Bond Distances (?) and Angles (
o
) for Th(SeO
3
)(SeO
4
)............. 140 
- xxi - 
Table 6.3.  Selected Bond Distances (?) and Angles (
o
) for  
 Th(IO
3
)
2
(SeO
4
)(H
2
O)
3
?H
2
O....................................................................... 144 
Table 6.4.  Selected Bond Distances (?) and Angles (
o
) for Th(CrO
4
)(IO
3
)
2
.............. 149 
Table 6.5.  Atomic Coordinates and Equivalent Isotropic Displacement  
 Parameters for Th(SeO
3
)(SeO
4
) (1)........................................................... 150 
Table 6.6.  Atomic Coordinates and Equivalent Isotropic Displacement  
 Parameters for Th(IO
3
)
2
(SeO
4
)(H
2
O)
3
?H
2
O (2)......................................... 151 
Table 6.7.  Atomic Coordinates and Equivalent Isotropic Displacement  
 Parameters for Th(CrO
4
)(IO
3
)
2
 (3)............................................................ 152 
Table 7.1.  Crystallographic data for Th
2
(CrO
4
)
4
(H
2
O)
2
 (1) and Th(SeO
3
)
2
 (2).......... 162 
Table 7.2.  Selected Bond Distances (?) for Th
2
(CrO
4
)
4
(H
2
O)
2
.................................. 167 
Table 7.3.  Selected Bond Distances (?) and Angles (
o
) for Th(SeO
3
)
2
...................... 178 
Table 7.4.  Atomic Coordinates and Equivalent Isotropic Displacement  
 Parameters for Th
2
(CrO
4
)
4
(H
2
O)
2
.............................................................. 179 
Table 7.5.  Atomic Coordinates and Equivalent Isotropic Displacement  
 Parameters for Th(SeO
3
)
2
.......................................................................... 180 
 
1 
Chapter 1 
INTRODUCTION 
RESEARCH GOALS 
The study of the actinides in various reaction environments has roots that extend 
back over 50 years.  The separation and purification of actinides through the precipitation 
of complexes of these elements with anions such as iodate and fluoride is a well-known 
process.  Thorium alone has been shown to form complexes with a plethora of oxoanions 
including, but not limited to, iodate, bromate, nitrate, chlorate, sulfate, phosphate, and 
molybdate, as well as fluoride.
1
  Uranium is known to complex with similar anions.  The 
separation of uranium isotopes includes methods such as laser separation, gaseous 
diffusion, and gas centrifuge separation; all utilize UF
6
.  Yet with the importance of 
obtaining pure samples of actinide compounds, with special emphasis on isotope 
purification for weapons or energy needs, little is known about the complexes that form 
in these processes.
2,3
 
It is essential to understand the interactions between the actinides and other 
chemical moieties that develop under particular conditions in order not only to purify the 
actinides, but to do so under the most ideal and efficient ways possible, primarily due to 
the radioactive nature of the elements under scrutiny.  Since the discovery of nuclear 
fission by Hahn and Strassmann in 1938, the greatest purity 
235
U and 
238
U are required to 
obtain specific percentages of these isotopes of for weapons and energy production.  
2 
Extraction of uranium from a pitch of natural sources can be cumbersome owing 
to the presence of nearly 40 elements in the mixture, not to mention the wide range of 
isotopes that must be separated to achieve the specific percentages necessary.
4
  
Removal, storage, and clean-up of the waste from nuclear fission more clearly 
accentuate the need for structural understanding of actinides. A large number of 
experiments remain to be conducted for the chemical nature of uranium to be understood.  
The lack of characterization of uranium-containing compounds demands further 
exploration of the structural aspects of this element.  Any correlations that could be 
developed between uranium, thorium, and neptunium, along with the remaining actinides, 
would augment the knowledge base for this relatively poorly understood section of the 
periodic table.   
The purpose of this research is to increase the information available for the 
fundamental knowledge of the chemistry of the early actinides, as well as advance the 
possibility of practical application of compounds containing these elements.  
 
HYDROTHERMAL SYNTHESIS 
Defined as a chemical process that involves the use of water as a solvent and 
reaction conditions at a temperature in excess of 100 ?C and pressure above 1 bar,
5
 the 
mild hydrothermal synthetic method is preferred for several reasons.  The ability to 
mimic natural geological processes is ideal for recreating the conditions under which 
minerals are formed.
6
  This technique can thus be used to synthesize the minerals in the 
laboratory.
7,8
  When attempting to understand the types of compounds that are formed by 
the actinides in the environment, whether the actinides are deposited through natural 
3 
sources or because of fission reactor waste, the hydrothermal method can bring insight 
into the interactions of these elements and other components in the mixture through the 
manufacture of crystalline solids.  The structures of these compounds may be identical to 
or resemble the coordination environments of the actinides in environmental conditions.  
For example the mineral uraninite is a natural analogue of reactor waste.  This, as well as 
other mineral structures, can be synthesized using this method, which therefore mimics 
natural geological processes.  The study of such naturally occurring actinide compounds 
may lead to the eventual discovery of cleaning processes or storage mechanisms for the 
radioactive elements.   
Each of the mild hydrothermal reactions in this report was carried out in a PARR 
4749 autoclave which consists of a 23-mL PTFE liner encapsulated by a stainless steel 
reaction bomb (Figure 1.1).  The reactants were loaded into the liner with the water added 
drop-wise to the solid reactants.  Any acid or base solutions were then added drop-wise to 
the reaction mixture.  The autoclave was then sealed and placed in a box oven preheated 
to 100 to 230 ?C.  Temperatures above that range risk the break-down of the PTFE liner.  
Autogenetic pressure created within the liner is proportional to the amount of water in 
and temperature of the autoclave.  The reaction mixture was heated for a number of days, 
usually between one and six days, and then cooled to room temperature.  The rate of 
cooling can have a high impact on not only the size of the crystals,
9
 but the product 
itself.
10
   
The compounds synthesized can be extremely sensitive to temperature, volume of 
water, pH, stoichiometry of reactants, and rate of cooling.  Solvation of reactants that are 
rather insoluble in aqueous media can be achieved under these conditions.  The  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 1.1.  A diagram of a PARR 4749 autoclave.  The reactant mixture is held inside 
the Teflon cup with the body, spring disc, and plates containing the autogenetic pressure. 
4 
5 
addition of mineralizing agents, such as F
-
,
11
 Cl
-
,
12
 OH
-
,
13
 and NO
3
-
,
14
 into the reaction 
mixture can also aid in the dissolution of the reactants, whereas without these agents, no 
reaction would occur.  Due to the sensitivity of the reactions conditions, the use of a 
modified compositional diagram is necessary to vary these conditions in order to 
synthesize crystalline phases (Figure 1.2).
11
 
 
THE ACTINIDES 
The vast interest in the chemistry of the actinides can be attributed to several 
factors.  Oxidation states of the early actinides that are rare in other elements are 
accessible and extremely stable in the solid state (Table 1.1).
15,16
  This stability along 
with the ability to form numerous coordination modes
17
 can yield large numbers of 
extremely varied compounds.  Although the lanthanides contain the same types of 
valence orbitals as the actinides (Table 1.2), namely the lanthanide 4f and the actinide 5f, 
the actinides can participate in more covalent bonding than the lanthanides.  The 4f 
electrons are buried deep within the core of the atom and are therefore heavily shielded, 
thus restricting the covalency of the bonding of the atom.  The 5f orbitals are much more 
accessible to ligating atoms leading to varied and strong bonding motifs.   
Higher oxidation states of early actinide elements require a counter to the strain of 
the high charge.  This is achieved in the case of the actinides, namely uranium, 
neptunium, and plutonium, with a valency of V or higher, with a trans dioxo actinyl unit 
forming as an AnO
2
n+
 (n = 1 or 2) cation (Figure 1.3).  This dioxo cation is nearly linear  
in nature and is highly symmetrical with little deviation in bond length between the metal 
center and the two different oxo atoms.  Other examples of this phenomenon include 
 
 
 
 
 
6 
Figure 1.2.  A compositional diagram of UO
3
, HF, and homopiperazine showing the 
variation of reaction stoichiometries and compounds produced.  The reactants were in 
1mL of water at 180 ?C for 72 h. 
7 
Table 1.1.  The oxidation states of the early actinide series.  The environmentally 
important actinides are in bold. 
Th Pa U Np Pu Am Cm
       
III III III III III III III 
IV IV IV IV IV IV IV 
 V V V V V  
 VI VI VI VI 
  VII VII   
 
8 
Table 1.2.  The ground-state electron configuration of the lanthanides and the actinides. 
 Lanthanide Configuration   Actinide Configuration 
          
La  lanthanum  5d
1
6s
2
 Ac  actinium  6d
1
7s
2
Ce cerium 4f
1
 5d
1
6s
2
 Th thorium 5f
1
 6d
1
7s
2
Pr praseodymium 4f
3
  6s
2
 Pa protactinium 5f
2
 6d
1
7s
2
Nd neodymium 4f
4
  6s
2
 U uranium 5f
3
 6d
1
7s
2
Pm promethium 4f
5
  6s
2
 Np neptunium 5f
4
 6d
1
7s
2
Sm samarium 4f
6
  6s
2
 Pu plutonium 5f
6
  7s
2
Eu europium 4f
7
  6s
2
 Am americium 5f
7
  7s
2
Gd gadolinium 4f
7
 5d
1
6s
2
 Cm curium 5f
7
 6d
1
7s
2
Tb terbium 4f
9
  6s
2
 Bk berkelium 5f
9
  7s
2
Dy dysprosium 4f
10
 6s
2
 Cf californium 5f
10
 7s
2
Ho holmium 4f
11
 6s
2
 Es einsteinium 5f
11
 7s
2
Er erbium 4f
12
 6s
2
 Fm fermium 5f
12
 7s
2
Tm thulium 4f
13
 6s
2
 Md mendelevium 5f
13
 7s
2
Yb ytterbium 4f
14
 6s
2
 No nobelium 5f
14
 7s
2
Lu lutetium 4f
14
5d
1
6s
2
 Lr lawrencium 5f
14
 6d
1
7s
2
 
 
 
 
 
 
UO
2
2+
8-coordinate 
6-coordinate 
7-coordinate 
 
 
 
 
 
Figure 1.3.  The UO
2
2+
 uranyl unit exists as a nearly linear trans dioxo unit.  It generally 
forms in the solid state as a 6-coordinate tetragonal bipyramid, 7-coordinate pentagonal 
bipyramid, or an 8-coordinate hexagonal bipyramid. 
9 
10 
 VO
2
+
, MoO
2
2+
, and WO
2
2+
, though these cations exist as a highly bent cis dioxo unit.  
These AnO
2
n+
 oxygen atoms maintain a relatively short bond distance to the central 
heavy metal and do not usually participate in bonding to adjacent atoms when the central 
atom has a valency of VI or more, since the electron density of the oxygen atom is being 
siphoned to the electron deficient atom.  Metal?oxygen bond distances in the actinyl 
cation average approximately 1.83 ? for An(V), and are somewhat shortened for An(VI) 
to approximately 1.79?.   
Though these cations rarely bind in the axial direction, coordination is exuberant 
equatorially.  These moieties commonly form three types of polyhedra: the six-coordinate 
tetragonal bipyramid, the seven-coordinate pentagonal bipyramid, and the eight-
coordinate hexagonal bipyramid.
18,19
  In the case of UO
2
2+
, the pentagonal bipyramidal 
polyhedron is dominant and is contained in approximately 85% of known uranium(VI) 
structures.
18
 
Due to the terminal nature of this dioxo unit in the axial direction, a majority of 
the structures that are formed in the solid state containing these cations are of low 
dimensionality, rarely exceeding the two-dimensional sheet topology.
18
  Extended 
structures are formed through edge-sharing or corner-sharing interactions with adjacent 
actinyl units, or by being coordinated by ligands that act as bridging molecules to other 
actinyl cations
19
(Figure 1.4).  Depending on the variety of coordination modes available 
to a ligand, high dimensionality can be achieved through a combination of bridging and 
chelation, thus making the selection of ligand an important consideration. 
 
 
 
 
 
 
 
                        
 
 
Figure 1.4.  A depiction of the types of bonding in which the AnO
2
[X
5
] pentagonal 
bipyramid participates.  The top illustration is of corner-sharing; the bottom is of edge-
sharing.  No face-sharing of this unit has yet been discovered. 
11 
12 
There are few examples of these actinyl cations forming what is known as a 
cation-cation interaction (CCI).  This interaction occurs as the normally terminal axial 
oxo atom of AnO
2
n+
 coordinates to an equatorial site of an adjacent metal cation.  With 
the actinide ion in the +V oxidation state, the terminal oxo atom does have a partial 
negative charge, which can and does allow for this actinyl cation to form bonds via the 
oxo atom (Figure 1.5).  However, with the central ion in +VI or higher, the charge on the 
oxo atom then becomes partially positive, leading to this atom being particularly 
terminal.  These interactions quite often occur between two actinyl units.
20
  CCI?s were 
first indicated by Sullivan et al. in 1961 as the oxo atoms of NpO
2
+
 coordinated to UO
2
2+
 
in solution.
21
  Another 23 years would pass before the first solid-state example of CCI 
would be discovered in Na
4
(NpO
2
)
2
(C
12
O
12
)?8H
2
O through single crystal X-ray 
crystallography.
22
  To date few examples of CCI have been observed containing the 
UO
2
2+
 cation exclusively.
10,23-26
   
Those actinides in lower oxidation states also exhibit a variety of coordination 
environments.  Th(IV) for example has been observed to inhabit an eight-coordinate 
dodecahedron
27
 or square anti-prism,
28
 a nine-coordinate tricapped trigonal prism,
27
 and a 
ten-coordinate bicapped cube or bicapped square anti-prism.
29
  This diversity in 
complexation, as well as the ability to coordinate to a larger number of molecules than 
actinides in higher oxidation states, causes interest in the chemistry of thorium that 
overcomes the lack of accessible oxidation states.  The lack of terminal oxo actinyl atoms 
with atoms such as Th(IV) and U(IV) also increases the likelihood of obtaining extended 
structures with high dimensionality.
30-34
   
 
 
 
 
 
 
 
 
 
13 
Figure 1.5.  An example of a cation-cation interaction (CCI) in a sheet typology made 
exclusively of neptunyl units.   
14 
Developing the knowledge of the fundamental chemistry and complexation of the 
actinides has particular use in the field of nuclear fission waste containment.  All 
elements above atomic number 92 (uranium) are man-made, and therefore can not be 
examined in natural settings.  This presents a problem in that no known minerals can be 
discovered and evaluated to determine the types of compounds that can be created due to    
environmental conditions in which these synthesized elements will one day exist.  Any 
correlation that can be developed between these natural and synthesized crystalline 
compounds would serve to enhance storage and containment at and clean-up of sites such 
as Yucca Mountain, NV, and Hanford, WA.   
 
ORGANIC TEMPLATING 
The incorporation of structure-directing molecules in an extended structure is of 
interest due to the structural properties that can result, such as ion-exchange, absorption, 
magnetic ordering, and catalytic properties.
35-38
  These structure-directing molecules are 
typically organic in nature and often result in a desired low-dimensional extended 
structure (Figure 1.6).  Lower dimensionality enables a higher level of interaction 
between the compound and the environment, which can result in an increase in efficiency 
of structural properties such as ion exchange. 
The main use for these molecules in this body of work is to act as a bulky group 
in order to direct the structure to form around the molecule.  Assorted interactions, such 
as hydrogen bonding, between the structure-directing agent and the superstructure can 
affect the specific topology that forms in the structure.  Porous networks are quite often 
formed by the production of the superstructure around such entities as the ethylene  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 1.6.  A view down the b axis of the two-dimensional [C
5
H
14
N
2
][U
2
F
10
(H
2
O)].  
The uranium fluoride layers remain separated by homopiperazinium dications.  
15 
16 
diammonium and piperazinium cations, followed by elimination of the organic by 
decomposition, yielding the intact superstructure with an organic fragment or a simple 
proton remaining within the structure.  
 
STRUCTURE-PROPERTY RELATIONSHIPS 
The second-harmonic generation (SHG) of light requires that the structure be in a 
noncentrosymmetric space group.  These types of compounds are known as NLO, or 
nonlinear optical, materials.  One method to prepare such structures, beyond serendipity, 
is to attempt to incorporate asymmetric moieties into the structure.  The acquisition of 
SHG data is made by the use of 1064 nm (infrared) light source, in which the frequency 
of the light is doubled thus halving the wavelength of the incident light producing 532 nm 
(green) light.
50
  In order to most accurately describe the actual response of a compound, 
the sample must be sieved and then generally compared to the intensity of the response of 
alpha quartz.  Due to the weak response of this standard, the results are usually reported 
as being n ? ?-quartz with no specific units.   
The creation of an ion-exchange material is another difficult task.  The 
incorporation of cations or anions that have weak interactions with the superstructure into 
a structure of a compound can possibly have what is known as ion-exchange ability.  This 
structure property is the ability to uptake ions from the surrounding environment by 
replacing those ions with internal ions from the structure.  The rate at which the 
replacement occurs can vary according to the size of the gap which the ion occupies, 
conditions of the environment (i.e. the temperature of a surrounding solution, 
concentration of ions in the solution), and with the size of the ion.  The charge of the ion 
17 
is not always a controlling factor in the ions that are exchangeable with the original 
cation.  Cs[UO
2
Ga(PO
4
)
2
] (Figure 1.7) is a three-dimensional structure that shows no 
exchange with H
+
, Na
+
, or K
+
, but conversely exhibits a large uptake of both Ca
2+
 and 
Ba
2+
.
39
  
Although low-dimensional structures contain large gaps in which the ions can 
occupy, three-dimensional structures also have the ability to engage in ion exchange.  An 
additional benefit to high dimensionality is structure stability with ions that have been 
exchanged with ions that are smaller than those that were synthesized within the 
structure.  Three-dimensional structures with this ability are usually either classified as 
channel structures or open-framework structures.  These two structure types differ in that  
open frameworks generally have three intersecting channels perpendicular to the faces of 
the unit cell of a crystalline solid.  Both of these structure types can also be described as 
porous materials.  Robust actinide-containing ion-exchange materials have been largely 
focused upon due to the need for ion selective materials for 
90
Sr and 
137
Cs.  The 
extraction of these cations is essential for the storage and disposal of fission waste and 
the clean-up of nuclear waste contamination sites.
40-43
 
DESIRED ANIONS  
One of the particular aspects of the compounds reported in this work concerns the 
anions used in this research.  The creation of compounds with particular structural 
properties can be a factor in considering a choice of ion to incorporate into the structure.  
Anions such as iodate (IO
3
-
)
44,45
 (Figure 1.8) and selenite (SeO
3
2-
)
46,47
 (Figure 1.9) are 
both C
3v
 anions which have a stereochemically active lone electron pair that cause the 
atomic geometry to be trigonal prismatic.  IO
4
3- 48,49
 (Figure 1.10) is an approximate C
2v
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 1.7.  A depiction of one of the two intersecting channels that project down the a 
and b axes in the three-dimensional  [UO
2
Ga(PO
4
)
2
]
1-
 framework of Cs[UO
2
Ga(PO
4
)
2
].   
3
?
18 
 
 
 
 
 
 
 
 
Figure 1.8.  A projection of the structure of Hg(IO
3
)
2
 viewed along the a-axis (Hg = 
green, I = violet, O = red). 
19 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 1.9.  A depiction of the crystal structure of Au
2
(SeO
3
)
2
(SeO
4
) viewed along the b 
axis. 
20 
 
 
 
 
 
 
 
 
 
 
 
Figure 1.10.  A depiction of the IO
4
3-
 anion with lone electron pairs in polar opposite 
directions.   
21 
22 
anion with the same stereochemically active lone pair.  Alignment of these electron pairs 
would cause the structure to adopt a polar space group, thus yielding a compound which 
is likely to have an SHG response.   
Incorporation of polar anions is no guarantee of success in creating such NLO 
materials.  Quite often these electron pairs align in one section of the compound and, due 
to a mirror plane or inversion center, have an electron pair opposing it.  This occurrence 
will cancel any SHG response that would be there otherwise.  In the examples of 
Ag
2
(UO
2
)(SeO
3
)
2
, M[(UO
2
)(HSeO
3
)(SeO
3
)] (M = K, Rb, Cs, Tl), and Pb(UO
2
)(SeO
3
)
2
, 
only Pb(UO
2
)(SeO
3
)
2
 has an SHG response to the infrared light, because this compound 
crystallizes in the space group Pmc2
1
 which is polar about the c-axis.  The polarity in its 
structure can be attributed to the alignment of PbO
5
 polyhedra rather than alignment of 
the selenite anions (Figure 1.11).  Two metal centers with stereochemically active lone 
electron pairs were utilized in this structure in order to increase the probability of 
producing a compound with a polar structure.
51-54
  
Other types of anions can assist in the creation of NLO materials.  Tetrahedral and 
more often octahedral anions can undergo a second-order Jahn-Teller distortion,
48,55-57
 
making these initially symmetric anions polar.  IO
6
5- 10,48,58-60
 and TeO
6
6- 61-63
 (Figures 
1.12-13) can then act as the clearly polar anions do, thereby resulting in a possible 
noncentrosymmetric structure.  Quite often the structures containing these slightly polar 
anions owing to the large number of coordination possibilities of the oxoanions can result 
in an SHG response, or the occurrence of channeled or open framework structures, or 
both.  The large numbers of coordination modes that exist with such anions promote the 
formation of high dimensionality in the crystallized product.  
 
 
 
 
 
 
 
 
Figure 1.11.  This depiction of Pb(UO
2
)(SeO
3
)
2
 reveals the alignment of the PbO5 unit 
causing a positive SHG response. 
23 
 
  
 
 
 
 
 
 
 
 
 
 
Figure 1.12.  A depiction of a symmetric periodate (IO
6
5-
) anion. 
24 
 
 
 
 
O(10)
O(8)?
Te(1)
O(4)
O(3)
V(1)
O(2)
O(1)
O(12)
O(10)?
O(11)
O(2)?
O(6)
O(8)
O(9)
O(7)
O(4)?
O(7)?
Th(1)
O(3)?
O(9)?
V(2)
O(5)
 
 
 
 
 
 
 
Figure 1.13.  The thermal ellipsoid of Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
.  This clearly shows the 
extent of distortion that can be attributed to a second-order Jahn-Teller distortion. 
25 
26 
 
In the instance of K
2
[(UO
2
)
2
(VO)
2
(IO
6
)
2
O]?H
2
O, the distorted octahedra 
throughout the structure crystallize to form a polar structure with an SHG response of 300 
? ?-quartz (Figure 1.14).  These octahedra also form a channel structure that contains the 
hydrating water molecule and K
+
 cations (Figure 1.15).  Though ion exchange 
experiments were not conducted on this particular compound, the large gaps that exist in 
this structure are ideal for the replacement of K
+
 with other cations.   
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 1.14.  A depiction of K
2
[(UO
2
)
2
(VO)
2
(IO
6
)
2
O]?H
2
O showing the alignment of the 
distortions of the VO
6
 and IO
6
 units forming the overall polar structure. 
27 
 
 
 
 
 
 
 
 
 
Figure 1.15.  A second view of K
2
[(UO
2
)
2
(VO)
2
(IO
6
)
2
O]?H
2
O showing the elliptical 
channels that are filled with K
+
 cations and hydrating water molecules.   
28 
29 
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nd
 ed.; Katz, J. J., Seaborg, G. T., Morss, L. R., Eds.; Chapman and 
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32 
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33 
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34 
Chapter 2 
HYDROTHERMAL SYNTHESIS OF THE FIRST ORGANICALLY 
TEMPLATED NEPTUNIUM FLUORIDES
 
ABSTRACT 
Organically templated neptunium fluoride compounds, (C H N )Np F  (1) and 
2 10 2 2 10
(C
4
H
12
N
2
)
2
Np
2
F
12
?H
2
O (2), have been synthesized under mild hydrothermal conditions. 
The structure of 1 consists of NpF  tricapped trigonal prisms connected through edge- 
and corner-sharing interactions forming infinite two-dimensional [Np F ]  sheets, which 
are separated by the ethylenediammonium dications.
9
2 10
2-
  The structure of 2 consists of NpF
8
 
dodecahedra connected through edge sharing to form [Np
2
F
12
]
2-
 dimers which in turn 
form infinite one-dimensional chains.  These chains are separated by the piperazinium 
dication and occluded water molecules.  The C
4
H
12
N
2
2+
 cations form hydrogen-bonding 
interactions with the [Np
2
F
12
]
2-
 chains.  Crystallographic data:  (C H N )Np F , 
monoclinic, space group C2/c, a = 
2 10 2 2 10
16.0190(11), b = 7.0570(5), c = 8.7203(6) ?, ? = 
91.536(1)?, Z = 4 (T = 193 K).  Crystallographic data:  (C
4
H
12
N
2
)
2
Np
2
F
12
?H
2
O, 
monoclinic, space group C2/m, a =12.8670(10), b = 12.4790(10), c = 6.5671(5) ?, ? = 
107.0950(10)?, Z = 2 (T = 193 K).   
 
 
 
35 
INTRODUCTION 
Due to the various number of products that are accessible through the use of 
hydrothermal synthesis and in an effort to explore the structural properties of these 
various products, novel, low-dimensional, open-framework structures continue to be 
produced.  These structure types have the ability to exhibit a range of structure specific 
properties such as ion-exchange, absorption, magnetic ordering, and catalytic properties, 
and can therefore have potential use on a technical basis.
1-9
 An added benefit is the 
derivation of the fundamental aspects of the chemical nature of the components.  
The large number of coordination modes and different accessible oxidation 
states
10
 that are exhibited by neptunium products synthesized under hydrothermal 
conditions make the use of this and other actinide elements excellent candidates for 
starting materials for these applications.
11-15
  With large numbers of binding 
possibilities
15
 comes the ability to develop large numbers of products with desired 
structural properties.  Fluoride demonstrates evidence of success as a ligand in 
synthesizing solid-state phases due to fluoride being a remarkable donor ligand and 
mineralizing agent and the large number of possible geometries with the actinides.
13,15-19
  
Actinide fluoride products
13-14
 also show variation through the formation of 
oxofluoride,
14,20-24
 yielding even further structural variation to this series.   
The final component in this venture is the use of an organic molecule as a 
structure-directing agent.
25-27
  Previous compounds have made great use of these or 
similar organic molecules as templating agents to influence the type of structure that is 
produced.  These structure-directing molecules can be tailored in terms of charge, bulk, 
and shape to yield a desired result in many instances.  The method of organic templating 
 
36 
systems to obtain results is further evidenced in this work. 
As a continuation of previous work by Sykora, Almond, Walker, and co-workers, 
with the synthesis of (C
2
H
10
N
2
)M
2
F
10
1,2
 and (C
4
H
12
N
2
)
2
U
2
F
12
?H
2
O
3
 (M = Ce(IV) and 
U(IV)), this work is an example of the next logical step in understanding not only this 
area of structural synthesis, but can lead to new discoveries in the differences of chemical 
properties between electronically similar elements.  Should isostructural compounds be 
synthesized under identical conditions, then the evidence for using readily available 
238
U 
in place of limited 
237
Np for some exploratory research would be emboldened.  However, 
any differences between the two products would lead to the need for even further 
investigation into the factors that guide the formation of such products; either of these 
results is beneficial.  In this instance both products, (C
2
H
10
N
2
)Np
2
F
10
 and 
(C
4
H
12
N
2
)
2
Np
2
F
12
?H
2
O, prove to be isostructural with their respective analogues.   
 
EXPERIMENTAL 
 Synthesis.  
237
NpO  (99.9%, Oak Ridge), HF (48% wt, Aldrich), homopiperazine 
(C N H , 98%, Aldrich), and 
2
5 2 12
anhydrous piperazine (C
4
N
2
H
12
, 99%, Aldrich) were used 
as received. Distilled and Millipore-filtered water with a resistance of 18.2 M??cm was 
used in all reactions. Reactions were run in Parr 4749 autoclaves with 10 mL PTFE 
liners.  
Caution! 
237
Np (t
1/2
 = 2.14 x 10
6
 y) represents a serious health risk owing to ? and 
? emission especially because of its decay to the short- lived isotope 
233
Pa (t
1/2
 = 27.0 d), 
which is a potent ? and ? emitter.  All studies were conducted in a lab dedicated to studies 
on transuranium elements. This lab is located in a nuclear science facility and is equipped 
 
37 
with a HEPA-filtered hood and glovebox that is ported directly into the hood. A series of 
counters continually monitor radiation levels in the lab.  The lab is licensed by the state 
of Alabama (a NRC-compliant state) and Auburn University's Radiation Safety Office.  
All experiments were carried out with approved safety operating procedures.  All free-
flowing solids were handled in the glovebox, and products were only examined when 
coated with either water or Krytox oil and water. 
(C
2
H
10
N
2
)Np
2
F
10
 (1).  NpO
2
 (0.0100 g, 3.7x10
-5
 mol) and C
5
N
2
H
12
 (0.0074 g, 
7.4x10
-5
 mol) were loaded into a 10 mL PTFE-lined autoclave with 0.33 mL H
2
O. 0.0094 
mL 48% wt HF (4.7x10
-4
 mol) was then added drop-wise to the reaction mixture. The 
autoclave was sealed and placed in a box oven preheated at 180 ?C. The autoclave was 
heated for 72 h and then cooled at a rate of 9 ?C per hour to room temperature. The final 
reaction mixture consisted of a brown mother liquor and prismatic emerald green crystals 
bounded by ten planes of 1.  
(C
4
H
12
N
2
)
2
Np
2
F
12
?H
2
O (2).  NpO
2
 (0.100g, 3.7x10
-5
 mol) and C
4
N
2
H
10
 (0.0074g, 
7.4x10
-5
 mol) were loaded into a 10 mL PTFE-lined autoclave with 0.33 mL H
2
O.  
0.0094 mL 48% wt HF (4.7x10
-4
 mol) was then added drop-wise to the reaction mixture.  
The autoclave was sealed and placed in a box oven preheated at 130 ?C.  The autoclave 
was heated for 72 hours and then cooled at a rate of 9 ?C per hour to room temperature.  
The final reaction mixture consisted of a brown mother liquor and prismatic emerald 
green crystals and green prisms of 2. 
Crystallographic Studies.  Single crystals of 1 and 2 were mounted on a glass 
fiber and aligned on a Bruker SMART APEX CCD X-ray diffractometer.  Intensity 
measurements were performed using graphite monochromated Mo K? radiation from a 
 
38 
sealed tube and monocapillary collimator.  SMART (v 5.624) was used for preliminary 
determination of the cell constants and data collection control.  The intensities of 
reflections of a sphere were collected by a combination of 3 sets of exposures (frames).  
Each set had a different ? angle for the crystal and each exposure covered a range of 0.3? 
in ?.  A total of 1800 frames were collected with an exposure time per frame of 30 s. 
For 1 and 2 determination of integrated intensities and global refinement were 
performed with the Bruker SAINT (v 6.02) software package using a narrow-frame 
integration algorithm.  Face-indexed analytical absorption corrections were initially 
applied using XPREP, where individual shells of unmerged data were corrected 
analytically.
28
  These files were subsequently treated with a semiempirical absorption 
correction by SADABS.
29
  The program suite SHELXTL (v 6.12) was used for space 
group determination (XPREP), direct methods structure solution (XS), and least-squares 
refinement (XL).
28
  The final refinements included anisotropic displacement parameters 
for all atoms.  Secondary extinction was not noted.  Some crystallographic details are 
given in Table 2.1.     
 
RESULTS AND DISCUSSION 
Structures.  (C H N )Np F  (1) is isostructural with both U(IV)  and Ce(IV)
variants of (enH )M F  (M = U and Ce; enH  = ethylenediammonium dication). The 
structure of (C H N )Np F  consists of one crystalographically unique neptunium in a 
nine-coordinate tricapped trigonal prism bound by fluoride anions (Figure 2.1).  
2 10 2 2 10
1 2 
2 2 10 2
2 10 2 2 10
The nine fluoride anions of each neptunium polyhedra form three edge-sharing 
and two corner-sharing interactions to adjacent neptunium atoms, with a single fluoride  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
39 
Figure 2.1.  Thermal ellipsoid plot of (C
2
H
10
N
2
)Np
2
F
10
 (1) shown at 50% probability.  
 
40 
being terminal. These interactions are the foundation of the formation of infinite 
[Np
2
F
10
]
2-
 sheets (Figure 2.2) that are separated by ethylenediammonium dications 
(Figure 2.3).  Np?F bond distances (2.209(2) to 2.434(2)?) (Table 2.2) are within the 
normal range with F(3) having the shortest Np?F bond distance owing to the terminal 
nature of the F(3) atom. The terminal fluorides are directed between the layers and form 
hydrogen bonds with the enH
2
2+
 cations.  Hydrogen bonding distances for enH
2
2+
 
nitrogen atoms to the fluoride anions within the layers range from 2.714(7) to 3.133(7)? 
(N(1) to nearest F(3) atoms 2.714(7), 2.873(7), 3.133(7)?).  Each nitrogen atom has the 
possibility of forming hydrogen bonding interactions with six different fluoride anions, 
totaling twelve potential interactions for each enH
2
2+
 cation. 
(C
4
H
12
N
2
)
2
Np
2
F
12
?H
2
O (2) was determined to be isostructural with 
(C
4
H
12
N
2
)
2
U
2
F
12
?H
2
O
3
.  The structure of (C
4
H
12
N
2
)
2
Np
2
F
12
?H
2
O consists of one 
crystallographically unique neptunium in an eight-coordinate dodecahedron bound by 
fluoride atoms (Figure 2.4).  Of the eight fluoride atoms with each Np polyhedron, four 
are terminal.  Two of the remaining fluoride atoms form an edge-sharing interaction with 
an adjacent neptunium atom, forming the [Np
2
F
12
]
2-
 dimer.  This dimer then uses the last 
of the fluorides to link to two adjacent dimers, through edge sharing, leading to the 
formation of the one-dimentional structure (Figure 2.5).   
Neptunium to fluoride bond distances (2.167 ? to 2.427 ?) (Table 2.3) are within 
the normal range.  The terminal fluorides, F(1), F(4), F(5), F(5)?, have the shortest bond 
lengths to Np1 with 2.212(1) ?, 2.208(1) ?, and 2.167(1) ?, respectively, due to their 
terminal nature.  The [Np
2
F
12
]
2-
 chains are separated by the piperazinium dications as 
well as uncoordinated water molecules.   
 
 
 
 
41 
 
 
 
Figure 2.2.  A view down the a-axis depicting the [Np
2
F
10
]
2-
 sheets extended along the 
b/c plain. One NpF
9
 tricapped trigonal prism is connected to neighboring neptunium 
fluorides through three edge-sharing and two corner-sharing interactions. The terminal 
F(3) atoms are aligned along the a axis.
 
 
                
 
 
 
 
Figure 2.3.  A view of (C
2
H
10
N
2
)Np
2
F
10
 down the b-axis showing [Np F ]  sheets 
separated by enH  dications.
2 10
2-
2
2+
42 
 
Table 2.1.  Crystallographic Data for (C
2
H
10
N
2
)Np
2
F
10
 (1) and (C
4
H
12
N
2
)
2
Np
2
F
12
?H
2
O 
(2). 
Formula (C
2
H
10
N
2
)Np
2
F
10
(C
4
H
12
N
2
)
2
Np
2
F
12
?H
2
O 
Formula Mass 363.11 910.38
Color and habit green plate green prism 
Crystal System monoclinic monoclinic 
Space group C2/c (No. 15) C2/m (No. 12) 
a (?) 16.0190(11) 12.8670(10)
b (?) 7.0570(5) 12.4790(10) 
c (?) 8.7203(6) 6.5671(5)
? (?) 91.536(1) 107.0950(10) 
V (?
3
) 985.44(12) 1007.87(14) 
Z 4 2 
T (K) 193 193 
? (?) 
0.71073 0.71073 
Maximum 2? (deg.) 
56.58 56.62
?
calcd
 (g cm
?3
) 
4.894 3.000 
?(Mo K?) (cm
?1
) 
211.0 103.72
R(F) for F
o
2
 > 2?(F
o
2
)  
0.0144 0.0315 
R
w
(F
o
2
) 
b
0.0331 0.1072
a
 
()
RF F F F=???
oc o
.  
b
 
() ( )
RF wF F wF
wo
2
o
2
c
2
2
o
4
12
=?
?
?
?
?
?
?
??
?
?
?
?
?
?
. 
 
 
 
 
43 
 
 
 
 
 
 
 
 
C(2)?
C(1)
N(1)
N(1)?
C(1)?
C(2)
Np(1)
F(5)?
F(2)?
F(2)
F(3)
F(5)
F(3)?
F(1)
F(4)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 2.4.  Thermal ellipsoid plot of (C
4
H
12
N
2
)
2
Np
2
F
12
?H
2
O (2) shown at 50% 
probability.   
44 
 
 
 
 
 
 
 
 
 
 
        
 
 
 
 
 
a
b
c
 
 
 
 
 
Figure 2.5.  A depiction of the one-dimensional neptunium fluoride chains that form in 2.  
These chains are a result of corner-sharing interactions between the NpF
8
 polyhedra and 
extend down the c-axis.   
45 
 
46 
Table 2.2. Selected Bond Distances (?) and Angles (?) for (C
2
H
10
N
2
)Np
2
F
10
 (1). 
Distances (?) 
Np(1)?F(1)  2.298(2) Np(1)?F(4)? 2.347(2) 
Np(1)?F(1)? 2.305(2) Np(1)?F(5) 2.434(2) 
Np(1)?F(2) 2.303(2) Np(1)?F(5)? 2.311(2) 
Np(1)?F(2)? 2.343(2) Np(1)?Np(1)? 3.8487(3) 
Np(1)?F(3) 2.209(2) Np(1)?Np(1)? 3.9086(3) 
Np(1)?F(4) 2.312(2)   
Angles (?) 
F(1)?Np(1)?F(1)?  66.54(8) F(2)?Np(1)?F(4)? 138.45(7) 
F(1)?Np(1)?F(2)  69.77(7) F(2)?Np(1)?F(5) 63.28(7) 
F(1)?Np(1)?F(2)? 121.57(7) F(2)?Np(1)?F(5)? 76.61(7) 
F(1)?Np(1)?F(4)? 68.85(7) F(2)??Np(1)?F(3) 71.52(7) 
F(1)?Np(1)?F(5) 106.56(7) F(2)??Np(1)?F(4) 72.20(7) 
F(1)?Np(1)?F(5)? 73.28(7) F(2)??Np(1)?F(4)? 71.16(7) 
F(1)??Np(1)?F(2) 96.16(7) F(2)??Np(1)?F(5)? 64.61(7) 
F(1)??Np(1)?F(2)? 132.88(7) F(3)?Np(1)?F(4) 80.67(8) 
F(1)??Np(1)?F(4) 133.96(7) F(3)?Np(1)?F(5) 74.40(7) 
F(1)??Np(1)?F(4)? 70.58(7) F(3)?Np(1)?F(5)? 136.06(7) 
F(1)??Np(1)?F(5) 66.28(7) F(4)?Np(1)?F(4)? 142.40(5) 
F(1)??Np(1)?F(5)? 139.06(7) F(4)?Np(1)?F(5) 69.56(7) 
F(2)?Np(1)?F(2)? 130.88(5) F(4)?Np(1)?F(5)? 83.66(7) 
F(2)?Np(1)?F(3) 136.20(7) F(4)??Np(1)?F(5)? 88.23(7) 
F(2)?Np(1)?F(4) 74.76(7) F(5)?Np(1)?F(5)? 136.01(3) 
 
47 
Table 2.3. Selected Bond Distances (?) and Angles (?) for (C
4
H
12
N
2
)
2
Np
2
F
12
?H
2
O (2). 
Distances (?) 
Np(1)?F(1)  2.212(9) Np(1)?F(4) 2.208(6) 
Np(1)?F(2) 2.366(3) Np(1)?F(5) 2.167(6) 
Np(1)?F(2)? 2.366(3) Np(1)?F(5)? 2.167(6) 
Np(1)?F(3) 2.427(6) Np(1)?Np(1)? 4.0085(7) 
Np(1)?F(3)? 2.292(6) Np(1)?Np(1)? 4.0088(7) 
Angles (?) 
F(1)?Np(1)?F(2)  137.32(16) F(2)??Np(1)?F(3) 79.14(12) 
F(1)?Np(1)?F(2)?  137.32(16) F(2)??Np(1)?F(3) 76.23(13) 
F(1)?Np(1)?F(3) 69.0(3) F(2)??Np(1)?F(3) 137.92(19) 
F(1)?Np(1)?F(3)? 132.6(3) F(2)??Np(1)?F(3) 73.67(19) 
F(1)?Np(1)?F(4) 76.6(3) F(3)?Np(1)?F(3?) 63.6(2) 
F(1)?Np(1)?F(5) 77.09(18) F(3)?Np(1)?F(3?) 145.6(2) 
F(1)?Np(1)?F(5)? 77.09(18) F(3)?Np(1)?F(3?) 76.86(14) 
F(2)?Np(1)?F(2)? 64.3(2) F(3)?Np(1)?F(3?) 76.86(14) 
F(2)?Np(1)?F(3) 130.95(12) F(3)??Np(1)?F(4) 150.8(2) 
F(2)?Np(1)?F(3)? 79.14(12) F(3)??Np(1)?F(4) 92.01(19) 
F(2)?Np(1)?F(4) 76.23(13) F(3)??Np(1)?F(4) 92.01(19) 
F(2)?Np(1)?F(5) 73.67(19) F(4)?Np(1)?F(5) 95.84(17) 
F(2)?Np(1)?F(5)? 137.92(19) F(4)?Np(1)?F(5) 95.84(17) 
F(2)??Np(1)?F(3) 130.95(12) F(5)?Np(1)?F(5?) 148.3(3) 
 
 
48 
Stability and endurance of the crystal structure can be attributed to an extensive 
hydrogen bonding network between the organic molecules and the [Np
2
F
12
]
2-
 chains.  
Hydrogen bonding distances for C
4
H
12
N
2
 nitrogen to the nearest fluorides, F(1), F(3), 
F(4)?, and F(5), range from 2.770(1) to 2.982(1) ?, with F(4)? being the nearest.  Based 
on these atom distances, each nitrogen atom has the possibility of forming hydrogen 
bonding interactions with four different fluoride anions, totaling eight potential 
interactions for each piperazinium dication.  The hydrating water also has the prospect of 
hydrogen bonding with an O(1) to O(1)? distance of 2.658(1) ? and an O(1) to F(1) 
distance of 2.601(1) ? (Figure 2.6). 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 2.6.  A view down the c-axis showing the separation of the neptunium fluoride 
chains by the piperazinium dications, as well as the proximity of the chains to the 
nitrogen atoms caused by the hydrogen bonding interactions.  Due to the extent of the 
interaction between the chains and the dications, a large void is formed in the extended 
structure, which is then filled with the hydrating water molecule. 
49 
 
50 
Table 2.4.  Atomic Coordinates and Equivalent Isotropic Displacement Parameters for 
(C
2
H
10
N
2
)Np
2
F
10
 (1). 
Atom x y z U
eq
 (?
2
)
a
Np1 0.219411(7) 0.09331(17) 0.670144(13) 0.00792(7) 
F1 0.32224(12) 0.1783(3) 0.5047(2) 0.0121(4) 
F2 0.31883(12) 0.2760(3) 0.7957(2) 0.0128(4) 
F3 0.08169(13) 0.0751(3) 0.6639(2) 0.0151(4) 
F4 0.19746(13) 0.0471(3) 0.9285(2) 0.0130(4) 
F5 0.17109(13) 0.3849(3) 0.7876(2) 0.0125(4) 
N1 0.54642(18) 0.2430(4) 0.4833(3) 0.0153(6) 
H1a 0.5617 0.3304 0.5554 0.023 
H1b 0.5065 0.2931 0.4191 0.023 
H1c 0.5917 0.2099 0.4284 0.023 
C1 0.5127(2) 0.0725(5) 0.5599(4) 0.0148(7) 
H1d 0.4637 0.1080 0.6206 0.018 
H1e 0.5557 0.0182 0.6307 0.018 
 
a
 U
eq 
is defined as one-third of the trace of the orthogonalized U
ij
 tensor. 
 
 
 
 
 
 
 
 
51 
Table 2.5.  Atomic Coordinates and Equivalent Isotropic Displacement Parameters for 
(C
4
H
12
N
2
)
2
Np
2
F
12
?H
2
O (2). 
Atom x y z U
eq
 (?
2
)
a
Np1 0.90651(3) 0.5000 0.19614(5) 0.01785(17) 
F1 0.7436(7) 0.5000 -0.0404(14) 0.073(4) 
F3 0.9208(5) 0.5000 -0.1643(10) 0.0219(13) 
F5 0.8836(6) 0.6671(5) 0.1045(9) 0.0476(17) 
F2 1 0.6007(5) 0.5 0.0237(13) 
F4 0.7941(5) 0.5000 0.3937(10) 0.0237(13) 
N1 0.7758(10) 0.6670(8) -0.3411(13) 0.055(3) 
H1a 0.8052 0.6147 -0.4063 0.066 
H1b 0.7772 0.6423 -0.2083 0.066 
C1 0.8432(11) 0.7662(11) -0.3176(15) 0.053(3) 
H1c 0.9198 0.7490 -0.2404 0.063 
H1d 0.817 0.8196 -0.2325 0.063 
C2 0.6627(13) 0.6864(11) -0.4671(19) 0.058(4) 
H2a 0.6283 0.5000 -0.3889 0.07 
H2b 0.6219 0.5000 -0.4872 0.07 
O1 0.968(2) 0.5000 0.174(6) 0.33(4) 
 
a
 U
eq 
is defined as one-third of the trace of the orthogonalized U
ij
 tensor. 
 
52 
REFERENCES 
1. Almond, P. M.; Deakin, L.; Porter, M. J.; Mar, A.; Albrecht-Schmitt, T. E. Chem. 
Mater. 2000, 12, 3208.   
2. Sykora, R. E. & Albrecht-Schmitt, T. E. Chem. Mater. 2001, 13, 4399.  
3. Walker, S. M., Halasyamani, P. S., Allen, A., & O?Hare, D. J. Am. Chem. Soc. 
1999, 121, 10513. 
4. Wilson, S. T.; Lok, B. M.; Messina, C. A.; Cannan, T. R.; Flanigen, E. M. J. Am. 
Chem. Soc. 1982, 104, 1146.  
5. Gier, T. E.; Stucky, G. D. Nature 1991, 349, 508.  
6. Xu, R.; Chen, J.; Feng, C. Stud. Surf. Sci. Catal. 1991, 60, 63.   
7. Clearfield, A. Chem. Rev. 1988, 88, 125.  
8. Fogg, A. M.; Dunn, J. S.; Shyu, S.-G.; Cary, D. R.; O'Hare, D. Chem. Mater. 
1998, 10, 351. 
9. Davis, M. E.; Lobo, R. F. Chem. Mater. 1992, 4, 756.  
10. Fahey, Ja. A. Neptunium.  In The Chemistry of the Actinide Elements, 2
nd
 ed.; 
Katz, J. J., Seaborg, G. T., Morss, L. R., Eds.; Chapman and Hall:  London, 1986; 
Chapter 6, pp 443-498. 
11. Albrecht-Schmitt, T. E., Almond, P. M., & Sykora, R. E. Inorg. Chem. 2003, 42, 
3788.  
12. Almond, P. M.; Sykora, R. E.; Skanthakumar, S.; Soderholm, L.; Albrecht-
Schmitt, T. E.; Inorg. Chem 2004, 43, 958. 
13. Albrecht-Schmitt, T. E.; Almond, P. M.; Sykora, R. E.; Inorg. Chem. 2003, 42, 
3788. 
 
53 
14. Eller, G. P.; Asprey, L. B.; Kinkead, S. A.; Swanson, B. I.; Kissane, R. J.; J. 
Alloys and Comp. 1998, 269, 63. 
15. Shevchenko, A. P.; Serezhkin, V. N.; Radiochem 2002, 44, 5.  
16. Francis, R. J.; Halasyamani, P. S.; O'Hare, D. Chem. Mater. 1998, 10, 3131.   
17. Francis, R. J.; Halasyamani, P. S.; O'Hare, D. Angew. Chem., Int. Ed. 1998, 37, 
2214.  
18. Walker, S. M.; Halasyamani, P. S.; Allen, S.; O'Hare, D. J. Am. Chem. Soc. 1999, 
121, 10513.   
19. Almond, P. M.; Talley, C. E.; Bean, A. C.; Peper, S. M.; Albrecht-Schmitt, T. E. 
J. Solid State Chem. 2000, 154, 635.  
20. Francis, R. J.; Halasyamani, P. S.; Bee, J. S.; O'Hare, D. J. Am. Chem. Soc. 1999, 
121, 1609.   
21. Halasyamani, P. S.; Walker, S. M.; O'Hare, D. J. Am. Chem. Soc. 1999, 121, 
7415.   
22. Talley, C. E.; Bean, A. C.; Albrecht-Schmitt, T. E. Inorg. Chem. 2000, 39, 5174.   
 
23. Almond, P. M.; Deakin, L.; Mar, A.; Albrecht-Schmitt, T. E. Inorg. Chem. 2001, 
40, 866. 
24. Allen, S.; Barlow, S.; Halasyamani, P. S.; Mosselmans, J. F. W.; O'Hare, D.; 
Walker, S. M.; Walton, R. I. Inorg. Chem. 2000, 39, 3791.    
25. Kolis, J. W.; Korzenski, M. B. In Chemical Synthesis Using Supercritical Fluids; 
Jessop, P. G., Leitner, W., Eds.; Wiley-VCH: New York, 1999; pp 213-241. 
26. Cheetham, A. K.; F?rey, G.; Loiseau, T. Angew. Chem., Int. Ed. Engl. 1999, 38, 
3268. 
 
54 
27. Almond, P. M., Deakin, L., Porter, M. J., Mar, A., & Albrecht-Schmitt, T. E. 
Inorg. Chem., 2001, 40, 886. 
28. Sheldrick, G. M. SHELXTL PC, Version 6.12, An Integrated System for Solving, 
Refining, and Displaying Crystal Structures from Diffraction Data; Siemens 
Analytical X-Ray Instruments, Inc.: Madison, WI 2001. 
29. Sheldrick, G. M. SADABS 2001, Program for absorption correction using SMART 
CCD based on the method of Blessing: Blessing, R. H. Acta Cryst. 1995, A51, 33. 
 
 
55 
Chapter 3 
HYDROTHERMAL PREPARATION OF Ni(II)/U(IV) FLUORIDES WITH ONE-, 
TWO-, AND THREE-DIMENSIONAL TOPOLOGIES 
 
ABSTRACT 
 A modified compositional diagram for the reactions of Ni(C
2
H
3
O
2
)
2
?4H
2
O with 
UO
2
(C
2
H
3
O
2
)
2
?2H
2
O and HF in aqueous media under mild hydrothermal conditions (200 
?C) has been completed to yield three Ni(II)/U(IV) fluorides, Ni(H
2
O)
4
UF
6
?1.5H
2
O (1), 
Ni
2
(H
2
O)
6
U
3
F
16
?3H
2
O (2), and Ni(H
2
O)
2
UF
6
(H
2
O) (3).  The structure of 1 consists of 
one-dimensional columns constructed from two parallel chains of edge-sharing 
dodecahedral [UF
8
] units.  The sides of the columns are terminated by octahedral Ni(II) 
that occur as cis-[Ni(H
2
O)
4
F
2
] polyhedra.  In contrast, the crystal structure of 2 reveals a 
two-dimensional Ni(II)/U(IV) architecture built from edge-sharing tricapped trigonal 
prismatic [UF
9
] units.  The top and bottom of the sheets are capped by fac-[Ni(H
2
O)
3
F
3
] 
octahedra.  The structure of 3 is formed from [UF
8
(H
2
O)] tricapped trigonal prisms that 
edge-share with one another to form one-dimensional chains.  These chains are then 
joined together into a three-dimensional network by corner-sharing with trans-
[Ni(H
2
O)
2
F
4
] octahedra.  Crystallographic data: 1, orthorhombic, space group Cmcm, a = 
14.3383(8) ?, b = 15.6867(8) ?, c = 8.0282(4) ?, Z = 8; 2, hexagonal, space group 
 
56 
P6
3
/mmc, a = 7.9863(5) ?, c = 16.566(1) ?, Z = 2; 3, monoclinic, space group C2/c, a = 
12.059(1) ?, b = 6.8895(6) ?, c = 7.9351(7) ?, ? = 92.833(2)?, Z = 4. 
 
INTRODUCTION 
In recent years the synthesis of organically templated uranium fluorides has been 
the focus of considerable interest owing to both the diversity of structures observed and 
the physicochemical properties that these compounds display.
1-11
  For instance, the one-
dimensional homopiperazinium-templated U(IV) fluoride, (C
5
H
14
N
2
)
2
U
2
F
12
?2H
2
O, 
exhibits metamagnetic behavior.
7
  Likewise, unusual short-range ferromagnetic coupling 
is found in two-dimensional (C
2
H
10
N
2
)U
2
F
10
.
7
  Ion-exchange properties are also known 
for a series of U(IV) fluorides with sheet topologies similar to those observed in 
(C
2
H
10
N
2
)U
2
F
10
.
1,12
  In addition, several porous and three-dimensional network structures 
with U(VI) have been isolated with fluoride and other hard anions.    These      
compounds include [C
6
H
14
N
2
][(UO
2
)
2
F
6
],
11 
[(C
4
H
12
N
2
][U
2
O
4
F
6
],
4,5
 
[(C
2
H
5
)
2
NH
2
]
2
[(UO
2
)
5
(PO
4
)
4
],
13
 Na
2
(UO
2
)(Si
4
O
10
)?2.1H
2
O,
14
 RbNa(UO
2
)(Si
2
O
6
)?H
2
O,
14
 
[C
4
H
12
N
2
][(UO
2
)
2
(PO
3
H)
2
{PO
2
(OH)H}
2
],
15
 and 
[NH
4
]
3
[(UO
2
)
10
O
10
(OH)][(UO
4
(H
2
O)
2
]?2H
2
O.
16
  Based on these works, the possibility of 
preparing uranium-based materials with zeolitic topologies is starting to become a reality. 
In spite of these widespread efforts to understand the hydrothermal chemistry of 
uranium, mixed-metal compounds derived from hydrothermal conditions are lacking.  In 
fact, they are largely restricted to U(VI) chromates and molybdates that are known with 
both organic structure-directing agents
17
 and inorganic cations.
18-29
  In the latter case, 
however, the transition metal does not impart desirable electronic properties associated 
57 
with unpaired electrons on the metal centers.  Therefore, the preparation of mixed-metal 
uranium compounds with transition metals bearing d-electrons can be viewed as an 
important synthetic challenge that may give rise to mixed-metal compounds with atypical 
electronic properties.  The majority of well-characterized representatives of transition 
metal/uranium fluorides are found to contain transition metals in the +2 oxidation state, 
especially Ni(II), and U(VI) in the form of uranyl, UO
2
2+
, cations.  Members of this 
group include [Ni(H
2
O)
6
]
2
[(UO
2
)
2
F
8
]?2H
2
O,
30
 [Ni(H
2
O)
6
]
3
[(UO
2
)
4
F
14
],
31
 and 
[NH
4
]
2
[Ni(H
2
O)
6
][(UO
2
)
2
F
8
].
32
  Limited crystallographic information has also been 
reported for the mixed-metal U(IV) fluorides [M(H
2
O)
6
][U
2
F
10
]?2H
2
O (M = Co, Ni, 
Cu).
33
  The common feature of both of these Ni(II)/U(IV)/F and Ni(II)/U(VI)/F systems 
is that the transition metals are fully hydrated and are essentially serving as counterions 
that are not directly incorporated into the uranium fluoride extended or molecular 
structures.   
In this report we detail the preparation of three new Ni(II)/U(IV) fluorides, 
Ni(H
2
O)
4
UF
6
?1.5H
2
O (1), Ni
2
(H
2
O)
6
U
3
F
16
?3H
2
O (2), and Ni(H
2
O)
2
UF
6
(H
2
O) (3) under 
mild hydrothermal conditions.  These compounds display dimensionalities ranging from 
one-dimensional chains to two-dimensional layers to three-dimensional networks created 
through the combination of a variety of U(IV) polyhedra with various isomers of 
Ni(H
2
O)
6?x
F
x
 octahedra where there are linkages between Ni(II) and U(IV) via bridging 
fluoride anions.     
    
58 
EXPERIMENTAL 
 Syntheses.  UO
2
(C
2
H
3
O
2
)
2
?2H
2
O (98%, Alfa-Aesar), Ni(C
2
H
3
O
2
)
2
?4H
2
O (98%, 
Aldrich), and HF (48 wt.%, Aldrich) were used as received.  Distilled and Millipore 
filtered water was used in all reactions.  The resistance of the water was 18.2 M??cm.  
The PTFE liners used to contain these reactions were cleaned of contaminants by heating 
with distilled and Millipore-filtered water at 200 ?C for 3 d prior to use.  While the UO
3
 
contains depleted U, standard precautions for handling radioactive materials should be 
followed.  Old sources of depleted U should not be used, as the daughter elements of 
natural decay are highly radioactive and present serious health risks.   SEM/EDX 
analyses were performed using a JEOL 840/Link Isis instrument.  The reported 
preparations given herein are taken from a modified compositional diagram and represent 
the highest yields of pure phases obtained where possible.   
 Ni(H
2
O)
4
UF
6
?1.5H
2
O (1) and Ni(H
2
O)
2
UF
6
(H
2
O) (3).  UO
2
(C
2
H
3
O
2
)
2
?2H
2
O 
(212 mg, 0.500 mmol) and Ni(C
2
H
3
O
2
)
2
?4H
2
O (373 mg, 1.5 mmol) were loaded in a 23-
mL PTFE-lined autoclave.  Water (1 mL) was then added to the solids, followed by the 
drop-wise addition of HF (0.73 mL, 20 mmol).  The autoclave was sealed and placed in a 
box furnace and heated to 200 ?C.  After 72 h the furnace was cooled at 9 ?C/h to 23 ?C.  
The product consisted of an aquamarine colored solution over pale green tablets of 1 and 
large, dark green, roughly hexagonal blocks of 3.  The mother liquor was decanted from 
the crystals, which were then washed with water and methanol, and allowed to dry.  Yield 
of 1, 150 mg (62% yield based on U).  Yield of 3, 30 mg (12% yield based on U).  EDX 
analysis for Ni(H
2
O)
4
UF
6
?1.5H
2
O (1) and Ni(H
2
O)
2
UF
6
(H
2
O) (3) both provided a Ni:U 
ratio of 1:1. 
59 
 Ni
2
(H
2
O)
6
U
3
F
16
?3H
2
O (2).  UO
2
(C
2
H
3
O
2
)
2
?2H
2
O (170 mg, 0.4 mmol) and 
Ni(C
2
H
3
O
2
)
2
?4H
2
O (299 mg, 1.2 mmol) were loaded in a 23-mL PTFE-lined autoclave.  
Water (1 mL) was then added to the solids, followed by the drop-wise addition of HF 
(0.73 mL, 20 mmol).  The autoclave was sealed and placed in a box furnace and heated to 
200 ?C.  After 72 h the furnace was cooled at 9 ?C/h to 23 ?C.  The product consisted of a 
green solution over light green hexagonal tablets of 2.  The mother liquor was decanted 
from the crystals, which were then washed with water and methanol, and allowed to dry.  
Yield, 333 mg (67% yield based on U).  EDX analysis for Ni
2
(H
2
O)
6
U
3
F
16
?3H
2
O 
provided a Ni:U ratio of 2:3. 
Crystallographic Studies.  Single crystals of Ni(H
2
O)
4
UF
6
?1.5H
2
O (1), 
Ni
2
(H
2
O)
6
U
3
F
16
?3H
2
O (2), and Ni(H
2
O)
2
UF
6
(H
2
O) (3) were carefully selected and 
mounted on thin glass fibers with epoxy.  The mounted crystals were cooled to ?80 ?C 
using an Oxford Cryostream, and optically aligned on a Bruker SMART APEX CCD X-
ray diffractometer.  Intensity measurements were performed using graphite 
monochromated Mo-K? radiation from a sealed tube with a monocapillary collimator.  
SMART was used for preliminary determination of the cell constants and data collection 
control.  For all compounds, the intensities of reflections of a sphere were collected by a 
combination of 3 sets of exposures (frames).  Each set had a different ? angle for the 
crystal and each exposure covered a range of 0.3? in ?. A total of 1800 frames were 
collected with an exposure time per frame of 30 s. 
For all compounds, determination of integral intensities and global cell refinement 
were performed with the Bruker SAINT (v 6.02) software package using a narrow-frame 
integration algorithm.  A face-indexed analytical absorption correction was initially 
60 
applied using XPREP.
34
  Individual shells of unmerged data were corrected analytically 
and exported in the same format.  These files were subsequently treated with a semi-
empirical absorption correction with SADABS.
35
  The program suite SHELXTL (v 5.1) 
was used for space group determination (XPREP), direct methods structure solution 
(XS), and least-squares refinement (XL).
34
  Hydrogen atom positions were not located 
from the difference maps and were not included in the final refinements.  The final 
refinements included anisotropic displacement parameters for all non-hydrogen atoms 
and a secondary extinction parameter.   
 
RESULTS AND DISCUSSION 
Syntheses.  The preparation of Ni(H
2
O)
4
UF
6
?1.5H
2
O (1), Ni
2
(H
2
O)
6
U
3
F
16
?3H
2
O 
(2), and Ni(H
2
O)
2
UF
6
(H
2
O) (3) was accomplished by reacting Ni(C
2
H
3
O
2
)
2
?4H
2
O with 
UO
2
(C
2
H
3
O
2
)
2
?2H
2
O and HF in aqueous media at 200 ?C for 3 d followed by slow 
cooling to promote the growth of high-quality single crystals.  In this system use was 
made of a modified compositional diagram
5,7-10,36-39
 to determine the conditions under 
which various U(IV) solids crystallize.  In the course of these studies it was determined 
that the formation of 1-3 is remarkably sensitive to scale, and consistent isolation of solid 
U(IV) products could only be ensured by maintaining 20 mmol of HF in the reaction 
mixtures.  The most commonly observed crystalline solids were the less interesting U(IV) 
fluorides UF
4
??H
2
O and [Ni(H
2
O)
6
][U
2
F
10
]?2H
2
O.
33
  When the reactions were run at 
increased temperatures or with increased duration, the occurrence of these latter two 
compounds dominated compositional space, implying that these may be the result of 
thermodynamic control, whereas 1-3 are likely kinetic products.  There is no obvious 
correlation between product and reaction stoichiometry.       
  A series of control reactions were conducted to determine that the reduction of 
U(VI) to U(IV) in these syntheses is acid and acetate dependent, and likely corresponds 
to a decarboxylation reaction of the acetate anion.  The reduction of U(VI) to U(IV) has 
previously been observed in the hydrothermal synthesis of organically templated U(IV) 
fluorides.
1-3,5,6,8,9,11
  In these latter syntheses, aliphatic amines are apparently the reducing 
agents.
7
  For example, the reaction of excess ethylenediamine with UO
3
 and HF under 
hydrothermal conditions results in the reduction of U(VI) to U(IV) and the crystallization 
of (C
2
H
10
N
2
)U
2
F
10
 in a nearly quantitative yield.
6
  Crystallographic data for 1-3 are 
shown in Table 3.1.                 
Structures.  Ni(H
2
O)
4
UF
6
?1.5H
2
O (1).  The structure of 1 consists of one-
dimensional columns constructed from two interconnected, zigzagging chains of edge-
sharing dodecahedral [UF
8
] units as shown in Figure 3.1.  The sides of the columns are 
terminated by octahedral cis-[Ni(H
2
O)
4
F
2
] polyhedra.  The individual chains that edge-
share to form the columns of 1 are similar to the one-dimensional [MF
4/1
F
4/2
]
4?
 (M = Zr, 
U) chains found in several inorganic and organically templated U(IV) and Zr(IV) 
fluorides.
5,40-46
   
1
?
The nature of the edge-sharing of the [UF
8
] units is such that opposite edges are 
shared to create the one-dimensional chains running along the c-axis, and a single edge 
approximately orthogonal to the direction of chain propagation is shared to link two such 
chains together.  Therefore, six of the eight fluoride anions surrounding each U(IV)  
 
61 
 
  
 
 
 
 
 
 
 
 
 
 
 
Figure 3.1.  A view of the zigzagging chains of edge-sharing dodecahedral [UF
8
] units 
that are linked to form columns in Ni(H
2
O)
4
UF
6
?2.5H
2
O (1).  The periphery of these 
U(IV) fluoride columns are lined with cis-[Ni(H
2
O)
2
F
4
] octahedra. 
62 
Table 3.1.  Crystallographic data for Ni(H
2
O)
4
UF
6
?2.5H
2
O (1), Ni
2
(H
2
O)
6
U
3
F
16
?3H
2
O 
(2), and Ni(H
2
O)
2
UF
6
(H
2
O) (3). 
Compound Ni(H
2
O)
4
UF
6
?2.5H
2
O  Ni
2
(H
2
O)
6
U
3
F
16
?3H
2
O Ni(H
2
O)
2
UF
6
(H
2
O) 
Formula mass 527.84 1297.65 464.79 
Crystal system Orthorhombic Hexagonal Monoclinic 
Space group Cmcm (No. 63) P6
3
/mmc (No. 194) C2/c (No. 15) 
a (?) 14.3383(8) 7.9863(5) 12.059(1) 
b (?) 15.6867(8) 7.9863(5) 6.8895(6) 
c (?) 8.0282(4) 16.566(1) 7.9351(7) 
? (deg.) 90 90 90 
? (deg.) 90 90 92.833(2) 
? (deg.) 90 120 90 
V (?
3
) 1805.7(2) 915.0(1) 658.5(1) 
Z 8 2 4
T (?C) ?80 ?80 ?80 
? (?) 0.71073 0.71073 0.71073
?
calcd
 (g cm
?3
) 3.883 4.644 4.689 
? (Mo K?, 
cm
?1
) 
201.13 286.67 275.07
R(F) for F
o
2
 > 
2?(F
o
2
) 
a
 
0.0252 0.0237 0.0330 
R
w
(F
o
2
) 
b
 0.0692 0.0648 0.0878 
a
 
()
RF F F F=???
oc o
.  
b
 
() ( )
RF wF F wF
wo
2
o
2
c
2
2
o
4
12
=?
?
?
?
?
?
?
??
?
?
?
?
?
?
. 
63 
center are utilized in the formation of the uranium fluoride columns.  The two remaining 
fluoride anions are used to bind the octahedral Ni(II) atoms to the periphery of the  
columns.  The remaining four sites around the Ni(II) centers are occupied by terminal 
water molecules.  This requires the [Ni(H
2
O)
4
F
2
] polyhedra to have a cis geometry.  The 
[Ni(H
2
O)
4
UF
6
] columns are packed together in an interdigitated fashion, and combine 
to form a channel structure where the channels are filled with occluded water molecules.  
A view of the channel structure of 1 is shown in Figure 3.2.  There are two 
crystallographically unique water molecules within the channels; one of these is ordered 
and the other is disordered.  The U?F bond distances are within normal ranges and occur 
from 2.220(4) to 2.425(2) ?.  The Ni?O(H
2
O) distances of 2.072(5), 2.056(3) (? 2), and 
2.081(4) ? are uniformly longer than the two Ni?F distances of 2.003(3) ?, and compare 
well with those found in [Ni(H
2
O)
6
][M
2
F
10
]?2H
2
O (M = Ce, U).
104,125
  Selected bond 
distances are summarized in Table 3.2.  These bond distances were used to calculate the 
bond valence sums for the Ni(II) and U(IV) atoms with values of 1.98 and 4.07 being 
found, respectively.
47,48
                       
1
?
Ni
2
(H
2
O)
6
U
3
F
16
?3H
2
O (2).  In contrast to the one-dimensional features found for 
1, the crystal structure of 2 reveals a highly symmetric two-dimensional Ni(II)/U(IV) 
architecture built from edge-sharing tricapped trigonal prismatic [UF
9
] units.  The sheets 
are capped on both sides by [Ni(H
2
O)
3
] moieties.  In this compound a hexagonal planar 
[U
3
F
3
] ring is found to repeat throughout the layers.  In the center of this ring is a ?
3
-F 
atom residing on a ?6m2 special position.  This central atom also represents the core atom 
utilized in the simultaneous edge-sharing of three [UF
9
] tricapped trigonal prisms where 
 
64 
 
 
 
 
Figure 3.2.  A view of the channel structure of Ni(H
2
O)
4
UF
6
?2.5H
2
O (1) formed by the 
interdigitation of the Ni(H
2
O)
4
UF
6
 columns.  Ordered and disordered water molecules fill 
the channels in this compound.   
65 
66 
Table 3.2.  Selected Bond Distances (?) for Ni(H
2
O)
4
UF
6
?2.5H
2
O (1).  
U(1)?F(1) (? 2) 2.252(3) Ni(1)?F(1) (? 2) 2.003(3) 
U(1)?F(2) 2.357(3) Ni(1)?O(1) 2.072(5) 
U(1)?F(3) 2.220(4) Ni(1)?O(2) (? 2) 2.056(3) 
U(1)?F(4) (? 2) 2.425(2) Ni(1)?O(3) 2.081(4) 
U(1)?F(5) 2.303(3)   
U(1)?F(6) (? 2) 2.390(2)   
 
each of these units shares two common edges with each other to form a trimer as shown 
in Figure 3.3.  Therefore, while the structure is derived from a single [UF
9
] tricapped 
trigonal prism, the trimer is more useful for visualizing the repeating pattern in the layers.  
The formation of this fluoride centered ring utilizes three of the nine fluoride anions 
surrounding each U(IV) center.  For each [UF
9
] unit an additional four fluoride ligands 
are occupied in edge-sharing with two neighboring trimers to form the two-dimensional 
[U
3
F
16
]
4?
 sheets depicted in Figure 3.4.     
2
?
The remaining two fluoride ligands in each [UF
9
] tricapped trigonal prism are 
directed above and below each layer.  The trimer of edge-sharing [UF
9
] therefore has 
three fluoride ions arranged above and below the rings for the binding of the Ni(II) 
centers.  This necessitates that the [Ni(H
2
O)
3
F
3
] octahedra have a fac geometry.  The 
Ni(II) atoms reside directly above and below the ?
3
-F atoms in the center of 
[UF
2/1
F
6/2
F
1/3
]
3
 trimers and are located on 3m sites.  A view down the c-axis showing the 
capping of a [U
3
F
16
]
4?
 sheet with fac-[Ni(H
2
O)
3
F
3
] octahedra is shown in Figure 3.5.  
The remaining water molecules in 2 are located between the layers in channels that run 
along the c-axis.  The U?F bond distances range from 2.222(4) to 2.354(3) ?.  The three 
Ni?O(H
2
O) distances of 2.061(5) ? are again longer than the three Ni?F bond distances 
of 2.017(4) ?.  Selected bond distances for 2 are summarized in Table 3.3.  The bond 
valence sums for the Ni(II) and U(IV) atoms in 2 were calculated to be 1.97 and 4.14, 
respectively.
139,140
            
2
?
Ni(H
2
O)
2
UF
6
(H
2
O) (3).  The tricapped trigonal prismatic geometry observed for 
U(IV) in 2 is observed again in 3.  However, one of the fluoride anions has been replaced 
by a water molecule to yield [UF
8
(H
2
O)] units.  The assignment of this ligand as  
67 
 
 
 
 
 
 
                         
 
 
 
 
 
Figure 3.3.  A depiction of the cyclic trimer formed from the edge-sharing of three [UF
9
] 
tricapped trigonal prisms in Ni
2
(H
2
O)
6
U
3
F
16
?3H
2
O (2). 
68 
 
 
 
 
 
 
 
 
 
 
Figure 3.4.  A representation of the two-dimensional [U
3
F
16
]
4?
 sheets created from the 
edge-sharing of [UF
9
] tricapped trigonal prisms with two neighboring trimers formed 
from these same [UF
9
] units in Ni
2
(H
2
O)
6
U
3
F
16
?3H
2
O (2). 
2
?
69 
 
 
 
 
 
 
 
 
Figure 3.5.  A view down the c-axis showing the capping of a [U
3
F
16
]
4?
 sheet with fac-
[Ni(H
2
O)
3
F
3
] octahedra.  Occluded water molecules in 2 are located between the layers in 
channels that run along the c-axis. 
2
?
70 
71 
Table 3.3.  Selected Bond Distances (?) for Ni
2
(H
2
O)
6
U
3
F
16
?3H
2
O (2).  
U(1)?F(1) (? 2) 2.354(3) Ni(1)?F(4) (? 3) 2.017(4) 
U(1)?F(2) 2.3261(3) Ni(1)?O(1) (? 3) 2.061(5) 
U(1)?F(3) (? 4) 2.363(2)   
U(1)?F(4) (? 2) 2.222(4)   
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
72 
 
water can be inferred from its U?O bond distance of 2.543(9) ?, which is considerably 
longer than the average U?F distance of 2.309(4) ? in this compound.  This designation 
is also supported by the bond valence sum of the O atom at 0.31, which is well within 
normal range for bound water molecules.  The [UF
8
(H
2
O)] tricapped trigonal prisms 
edge-share with one another to form one-dimensional chains as shown in Figure 3.6.  
Unlike the zigzagging one-dimensional chains found in 1, the chains of 3 are 
approximately linear.  These chains are in turn linked together by corner-sharing with 
trans-[Ni(H
2
O)
2
F
4
] octahedra into a three-dimensional network.   
When viewed down the c-axis, as shown in Figure 3.7, it can be seen that both the 
water molecules bound to the Ni(II) centers and the water molecule ligating the U(IV) 
atoms are located within channels running down the c-axis.  The water molecules are 
sufficiently separated from one another to preclude hydrogen bonding being the driving 
force behind the formation of this particular structure type.  Selected bond distances for 3 
are summarized in Table 3.4.  The bond valence sums for the Ni(II) and U(IV) atoms in 3 
were calculated to be 2.01 and 4.16, respectively.
47,48
  An analysis of the bond valence 
sums for 1-3 reveals little variance in the sums for Ni(II) and U(IV) and supports their 
assignment in these oxidation states.              
 
CONCLUSIONS  
 This present study represents the first in a series of investigations that have 
demonstrated that mixed-metal 3d transition metal-U(IV) fluorides with a wide range of 
structures can be prepared under mild hydrothermal conditions.  This preparative and  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 3.6.  The [UF
8
(H
2
O)] tricapped trigonal prisms in Ni(H
2
O)
2
UF
6
(H
2
O) (3) edge-
share with one another to form one-dimensional chains. 
73 
 
 
 
 
 
74 
Figure 3.7.  A view down the c-axis of the three-dimensional network structure of 
Ni(H
2
O)
2
UF
6
(H
2
O) (3) demonstrating that both the water molecules bound to the Ni(II) 
centers and the water molecules ligating the U(IV) atoms reside within channels running 
along this same axis. 
75 
Table 3.4.  Selected Bond Distances (?) for Ni(H
2
O)
2
UF
6
(H
2
O) (3).  
U(1)?F(1) (? 2) 2.244(4) Ni(1)?F(1) (? 2) 1.990(3) 
U(1)?F(2) (? 2) 2.292(4) Ni(1)?F(2) (? 2) 2.006(3) 
U(1)?F(3) (? 2) 2.306(3) Ni(1)?O(1) (? 2) 2.070(6) 
U(1)?F(3)? (? 2) 2.392(4)   
U(1)?O(2) 2.543(9)   
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
76 
structural study has given rise to ongoing magnetic susceptibility measurements whose 
goal is to determine whether coupling between the expanded 5f orbitals of uranium and 
nd orbitals of transition metals can be mediated by bridging fluoride anions. 
 
77 
Table 3.5.  Atomic Coordinates and Equivalent Isotropic Displacement Parameters for 
Ni(H
2
O)
4
UF
6
?2.5H
2
O (1). 
Atom x y z U
eq
 (?
2
)
a
 
U1 0.5 0.129032(13) 0.9968(2) 0.00753(12) 
Ni1 0.25783(5) 0.16054(5) 0.75 0.00977(19) 
F1 0.35193(18) 0.16476(16) 0.9342(3) 0.0128(5) 
F2 0.5 0.2104(3) 0.75 0.0139(10) 
F3 0.5 0.2649(2) 0.0739(4) 0.0137(7) 
F4 0.5931(3) 0 0 0.0107(8) 
F5 0.5 0.0542(3) 0.75 0.0140(10) 
F6 0.4124(3) 0.1280(2) 0.25 0.0108(7) 
O1 0.2769(3) 0.0296(3) 0.75 0.0147(9) 
O2 0.1606(2) 0.1536(2) 0.9378(4) 0.0159(6) 
O3 0.2555(3) 0.2932(3) 0.75 0.0128(8) 
O4 0.5 0.386(2) 0.75 0.216(15) 
O5 0.0878(7) 0.0074(5) 0.0620(12) 0.035(2) 
 
a
 U
eq 
is defined as one-third of the trace of the orthogonalized U
ij
 tensor. 
 
 
 
 
 
 
 
78 
Table 3.6.  Atomic Coordinates and Equivalent Isotropic Displacement Parameters for 
Ni
2
(H
2
O)
6
U
3
F
16
?3H
2
O (2). 
Atom x y z U
eq
 (?
2
)
a
 
U1 0.49851(2) 0.50149(2) 0.75 0.00786(18) 
Ni1 0.6667 0.3333 0.55152(8) 0.0115(3) 
F1 0.3223(8) 0.1612(4) 0.75 0.0163(12) 
F2 0.6667 0.3333 0.75 0.0108(18) 
F3 0.5599(7) 0.7799(3) 0.6763(2) 0.0179(8) 
F4 0.5482(3) 0.4518(3) 0.6224(2) 0.0164(8) 
O1 0.4145(8) 0.2073(4) 0.4852(3) 0.0182(10) 
O2 0 0 0.6115(11) 0.079(6) 
O3 0 0 0.75 0.021(4) 
 
a
 U
eq 
is defined as one-third of the trace of the orthogonalized U
ij
 tensor. 
 
 
 
 
 
 
 
 
 
 
79 
Table 3.7.  Atomic Coordinates and Equivalent Isotropic Displacement Parameters for 
Ni(H
2
O)
2
UF
6
(H
2
O) (3). 
Atom x y z U
eq 
(?
2
)
a
 
U1 0 0.51807(5) 0.75 0.0053(2) 
Ni1 0.25 0.25 1 0.0064(3) 
F1 0.1196(3) 0.2862(6) 0.8394(4) 0.0096(8) 
F2 0.8294(3) 0.6442(7) 0.8036(4) 0.0106(8) 
F3 0.9313(3) 0.6364(7) 0.4938(4) 0.0109(8) 
O1 0.1834(7) 0.985(7) 1.0650(10) 0.0121(13) 
O2 0 0.88721(3) 0.75 0.021(2) 
 
a
 U
eq 
is defined as one-third of the trace of the orthogonalized U
ij
 tensor. 
80 
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46. Laval, J. P.; Papiernik, R.; Frit, B. Acta Crystallogr. 1978, B34, 1070. 
47. Brown, I. D.; Altermatt, D. Acta Crystallogr. 1985, B41, 244. 
48. Brese, N. E.; O?Keeffe, M. Acta Crystallogr. 1991, B47, 192. 
 
 
84 
Chapter 4 
STRUCTURE AND PROPERTIES OF THE THORIUM VANADYL 
TELLURATE, Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
 
 
ABSTRACT 
The hydrothermal reaction of Th(NO
3
)
4
?xH
2
O with V
2
O
5
 and H
6
TeO
6
 at 200 ?C 
under autogenous pressure results in the formation of Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
 as a pure 
phase.  The single crystal X-ray data indicates that Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
 possesses a 
three-dimensional structure constructed from ThO
9
 tricapped trigonal prisms, VO
5
 
distorted square pyramids, VO
4
 distorted tetrahedra, and TeO
6
 distorted octahedra.  Both 
of the vanadium polyhedra contain VO
2
+
 vanadyl units with two short V=O bond 
distances.  The tellurate octahedron is tetragonally distorted, and utilizes all of its oxygen 
atoms to bond to adjacent metal centers, sharing edges with ThO
9
 and VO
5
 units, and 
corners with two ThO
9
, one VO
5
, and two VO
4
 polyhedra.  Crystallographic data: 
Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
, orthorhombic, space group Pbca, a = 12.6921(7), b = 
11.5593(7), c = 13.0950(8) ?, Z = 8 (T = 193 K).  The UV-vis diffuse reflectance 
spectrum of Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
 shows vanadyl-based charge-transfer absorption 
features.  Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
 decomposes primarily to Th(VO
3
)
4
 when heated at 600 
?C in air.  
 
85 
INTRODUCTION 
Periodate, IO
6
5?
, and tellurate, TeO
6
6?
, have played pivotal roles in the isolation of 
transition metal complexes with unusually high oxidation states.
1
  The tellurate anion has 
been shown to stabilize Ru(VI) and Os(VI) in Na
6
[RuO
2
{TeO
4
(OH)
2
}
2
]?16H
2
O
2
 and 
Rb
2
Na
4
[OsO
2
{TeO
4
(OH)
2
}
2
]?18H
2
O,
3
 Pd(IV) in Na
8
K
2
H
4
[Pd
2
Te
4
O
24
H
2
]?20H
2
O,
4
 Cu(III) 
in Na
5
[Cu{TeO
4
(OH)
2
}
2
]?16H
2
O,
5
 Ag(III) in Na
5
[Ag{TeO
4
(OH)
2
}
2
]?16H
2
O,
2
 and Au(III) 
in Na
5
[Au{TeO
4
(OH)
2
}
2
]?16H
2
O.
6
  By comparison, well-characterized examples of 
actinide periodate and tellurate complexes are sparse.
1
  There are only two known uranyl 
periodates, A[(UO
2
)
3
(HIO
6
)
2
(OH)(O)(H
2
O)]?1.5H
2
O (A = Li ? Cs, Ag)
7
 and 
K
2
[(UO
2
)
2
(VO)
2
(IO
6
)
2
O]?H
2
O,
8
 both of which possess polar open-framework structures, 
and no known examples of actinide tellurate compounds.
1
  In addition to offering the 
possibility of stabilizing high oxidation states in actinides, periodate and tellurate provide 
the opportunity to build structures with three-dimensional connectivity
9,10
 owing to their 
approximately octahedral geometries and their ability to bind a large number of metal 
centers.
1,5,6
 
In an effort to understand the structural chemistry of tellurate with actinides we 
have investigated the reaction of Th(IV) salts with a variety of tellurate sources, primarily 
under mild hydrothermal conditions.  These studies have resulted in the isolation of the 
mixed-metal thorium vanadyl tellurate, Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
, which represents the first 
actinide tellurate whose constitution is unambiguously defined.  This compound also 
provides information on vanadyl tellurate coordination, which is also absent from the 
literature.  Herein we report the structure and properties of Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
. 
    
86 
EXPERIMENTAL 
 Syntheses.  Th(NO
3
)
4
?xH
2
O (99%, Alfa-Aesar), V
2
O
5
 (99.9%, Alfa-Aesar), and 
H
6
TeO
6
 (99.5%, Alfa-Aesar) were used as received.  Reactions were performed in PTFE-
lined Parr 4749 autoclaves.  Distilled and Millipore-filtered water with a resistance of 
18.2 M??cm was used in all reactions.  Standard precautions were performed for 
handling radioactive materials during work with Th(NO
3
)
4
?xH
2
O
 
and 
Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
.  Semi-quantitative SEM/EDX analyses were performed using a 
JEOL 840/Link Isis instrument.  Th, V, and Te percentages were calibrated against 
standards.  The IR spectrum was collected on a Nicolet 5PC FT-IR spectrometer from a 
KBr pellet.            
Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
.  Th(NO
3
)
4
?xH
2
O (0.2812 g, 0.5857 mmol), V
2
O
5
 
(0.1061 g, 0.5834 mmol), and H
6
TeO
6
 (0.1128 g, 0.4912 mmol) were loaded into a 23-
mL PTFE-lined autoclave.  Water (1 mL) was then added to the reaction mixture.  The 
autoclave was sealed and placed into a box furnace and heated to 200 ?C.  After 6 d the 
reaction was cooled at a rate of 9 ?C/h to 23 ?C.  The product mixture consisted of 
clusters of acicular yellow crystals in a green mother liquor.  The mother liquor was 
decanted, and the crystals were then washed with water and methanol and allowed to dry.  
Yield, 299 mg (79% based on Th).  Phase purity was confirmed by powder X-ray 
diffraction measurements.  The measured powder pattern was compared with a pattern 
calculated from single crystal X-ray data using ATOMS (v. 5, Shape Software).  No 
extraneous diffraction peaks were observed.  IR (KBr, cm
?1
): 1613 (?, H
2
O, w), 979 (?, 
VO
2
+
, s), 964 (?, VO
2
+
, s), 955 (?, VO
2
+
, s), 930 (?, VO
2
+
, s), (?, V?O, Te?O, Th?O) 862 
87 
(s), 843 (m), 821 (w), 796 (w, sh), 760 (s), 724 (w, sh), 695 (s).  EDX measurements 
show a Th:V:Te ratio of approximately 1(27%):2(47%):1(26%). 
Thermal Analysis.  Thermal data for Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
 were collected 
using a TA Instruments, Model 2920 Differential Scanning Calorimeter (DSC) and a TA 
Q50 Thermogravimetric Analyzer (TGA).  Samples (~20 mg) were encapsulated in 
aluminum or platinum pans and heated at 10 ?C/min from 25 ?C to 600 ?C under a 
nitrogen atmosphere. 
UV-vis Diffuse Reflectance Spectra.  The diffuse reflectance spectrum of 
Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
 was measured from 1800 to 200 nm using a Shimadzu UV3100 
spectrophotometer equipped with an integrating sphere attachment with BaSO
4
 being 
used as the standard.  The Kubelka-Monk function was used to convert diffuse 
reflectance data to absorbance spectra.
11
     
X-ray Powder Diffraction Data.  Powder diffraction data were collected using a 
Rigaku Miniflex powder diffractometer using Cu K? (? = 1.54056 ?) radiation.  Data 
were compared with patterns from the ICDD database or with those calculated directly 
from single crystal data using ATOMS. 
Crystallographic Studies.  A single crystal of Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
 was 
mounted on a glass fiber and aligned on a Bruker SMART APEX CCD X-ray 
diffractometer.  Intensity measurements were performed using graphite monochromated 
Mo K? radiation from a sealed tube and monocapillary collimator.  SMART (v 5.624) 
was used for preliminary determination of the cell constants and data collection control.  
The intensities of reflections of a sphere were collected by a combination of 3 sets of 
exposures (frames).  Each set had a different ? angle for the crystal and each exposure 
88 
covered a range of 0.3? in ?.  A total of 1800 frames were collected with an exposure 
time per frame of 30 s. 
For Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
 determination of integrated intensities and global 
refinement were performed with the Bruker SAINT (v 6.02) software package using a 
narrow-frame integration algorithm.  A face-indexed analytical absorption correction was 
initially applied using XPREP, where individual shells of unmerged data were corrected 
analytically.
12
  These files were subsequently treated with a semiempirical absorption 
correction by SADABS.
13
  The program suite SHELXTL (v 6.12) was used for space 
group determination (XPREP), direct methods structure solution (XS), and least-squares 
refinement (XL).
12
  The final refinements included anisotropic displacement parameters 
for all atoms.  Secondary extinction was not noted.  Some crystallographic details are 
given in Table 4.1.     
 
RESULTS AND DISCUSSION 
Synthesis.  The challenge in preparing actinide tellurates and periodates is that 
these anions oxidize water and are reduced by two electrons from Te(VI) or I(VII) to 
Te(IV) or I(V).  Under hydrothermal conditions these processes occur quite rapidly, and 
coincidentally are a convenient method for crystallizing tellurite and iodate 
compounds.
14-18
  During the preparation of K
2
[(UO
2
)
2
(VO)
2
(IO
6
)
2
O]?H
2
O
8 
it was 
discovered that the presence of V
2
O
5
 inhibits the reduction of periodate.  We therefore 
applied this method to the synthesis of thorium tellurates and found that the reaction of 
Th(NO
3
)
4
?xH
2
O with V
2
O
5
 and telluric acid results in the isolation of a desired product,  
 
Table 4.1.  Crystallographic Data for Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
. 
           
Formula Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
 
Formula Mass 657.55 
Color and habit yellow needle 
Crystal System orthorhombic 
Space group Pbca (No. 61) 
a (?) 12.6921(7) 
b (?) 11.5593(7) 
c (?) 13.0950(8) 
V (?
3
) 1921.2(2) 
Z 8 
T (K) 193 
? (?) 0.71073 
Maximum 2? (deg.) 56.58 
?
calcd
 (g cm
?3
) 4.519 
?(Mo K?) (cm
?1
) 203.83 
R(F) for F
o
2
 > 
2 (
2
)
0.0250 
R
w
(F
o
2
) 
b
0.0622 
a
 
()
RF F F F=???
oc o
.  
b
 
() ( )
RF wF F wF
wo
2
o
2
c
2
2
o
4
12
=?
?
?
?
?
?
?
??
?
?
?
?
?
?
. 
 
 
 
 
 
 
89 
90 
              
Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
, that contains Th(IV), V(V), and Te(VI), in both high yield and 
purity. 
Structure of Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
.  The structure of Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
 
is three-dimensional in nature, and is constructed from ThO
9
 tricapped trigonal prisms, 
VO
5
 distorted square pyramids, VO
4
 distorted tetrahedra, and TeO
6
 distorted octahedra.  
An ORTEP diagram showing these building units is shown in Figure 4.1.  The oxidation 
states can be assigned in this compound as Th(IV), V(V) at both sites, and Te(VI).  The 
Th?O bond distances range from 2.282(4) to 2.601(5) ?.  The ThO
9
 units share one edge 
with the VO
5
 polyhedra and a second edge with the TeO
6
 octahedra.  This unit has six 
additional corner-sharing interactions: two with the VO
5
 distorted square pyramids, two 
with the VO
4
 distorted tetrahedra, and two more with the TeO
6
 octahedra.  These 
interactions result in three ?
3
-O atoms (O(3), O(4), and O(5)), and four ?
2
-O atoms (O(2), 
O(6), O(7), and O(10)).  The two remaining oxygen atoms (O(11) and O(12)) are 
concluded to be water molecules based on their long Th?O bond distances of 2.564(5) 
and 2.601(5) ?, their bond valence sums of 0.34 and 0.31, charge balance requirements, 
and the presence of water stretching and bending modes in the IR spectrum.  Selected 
bond distances and angles are given in Table 4.2.  
There are two crystallographically unique vanadium atoms in 
Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
 in two different coordination environments.  V(1) is in a five-
coordinate distorted square pyramidal geometry.  V(2) meanwhile is found in a distorted 
tetrahedral environment.  Both of the V(V) polyhedra contain a VO
2
+
 vanadyl unit with 
two short V=O bond distances.  V(1) has vanadyl oxygen bond lengths of 1.628(5) and  
 
 
 
 
 
 
 
 
 
 
Figure 4.1.  A view of the ThO
9
 tricapped trigonal prisms, VO
5
 distorted square 
pyramids, VO
4
 distorted tetrahedra, and TeO
6
 distorted octahedra in 
Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
.  50% probability ellipsoids are depicted.   
91 
92 
Table 4.2.  Selected Bond Distances (?) and Angles (
o
) for Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
. 
Distances (?) 
Th(1)?O(2)  2.384(4) V(1)?O(4)  2.044(4) 
Th(1)?O(3)  2.479(4) V(1)?O(5)  1.929(4) 
Th(1)?O(4)  2.430(4) V(2)?O(6) 1.654(5) 
Th(1)?O(5)  2.528(4) V(2)?O(7) 1.654(5) 
Th(1)?O(6)  2.455(5) V(2)?O(8)  1.771(4) 
Th(1)?O(7)  2.400(5) V(2)?O(9)  1.801(4) 
Th(1)?O(10)  2.282(4) Te(1)?O(3)  1.921(4) 
Th(1)?O(11)  2.564(5) Te(1)?O(4)  1.907(4) 
Th(1)?O(12)  2.601(5) Te(1)?O(5)  1.943(4) 
V(1)?O(1)  1.628(5) Te(1)?O(8)  1.948(4) 
V(1)?O(2)  1.671(5) Te(1)?O(9)  1.953(4) 
V(1)?O(3)  1.945(4) Te(1)?O(10)  1.829(4) 
Angles (?) 
O(1)?V(1)?O(2)  106.3(3) O(6)?V(2)?O(7)  111.2(3) 
O(10)?Te(1)?O(4) 101.61(17) O(3)?Te(1)?O(4) 159.49(17) 
O(10)?Te(1)?O(3) 98.90(17) O(10)?Te(1)?O(5) 178.60(19) 
O(4)?Te(1)?O(5) 78.98(17) O(3)?Te(1)?O(5) 80.51(17) 
O(10)?Te(1)?O(8) 88.04(19) O(4)?Te(1)?O(8) 88.73(17) 
O(3)?Te(1)?O(8) 91.61(17) O(5)?Te(1)?O(8) 90.71(18) 
O(10)?Te(1)?O(9) 90.20(19) O(4)?Te(1)?O(9) 92.84(17) 
O(3)?Te(1)?O(9) 87.44(17) O(5)?Te(1)?O(9) 91.04(18) 
O(8)?Te(1)?O(9) 177.84(18)   
93 
 
1.671(5) ? to O(1) and O(2), respectively, and an O(1)?V(1)?O(2) bond angle of  
106.3(3)?.  The shorter V(1)?O(1) bond distance reflects its terminal nature.  The 
remaining four oxygen atoms in the V(1)O
5
 units are bridging.  The distortion of the 
V(1)O
5
 unit is evident in the bond angles of the square base of the unit.  The O(3)?V(1)?
O(4) angle is 74.84(17)?, which is close to that of the adjacent O(4)?V(1)?O(5) angle of 
76.02(16)?.  An examination of the remaining base angles shows this distortion with 
O(2)?V(1)?O(3) and O(2)?V(1)?O(5) having bonding angles of 94.97(19)? and 
99.47(19)? degrees, respectively.  The VO
5
 polyhedron contains several interactions to 
adjacent polyhedra.  There are two edge-sharing interactions: one with a ThO
9
 unit and a 
second with a TeO
6
 unit, both involving ?
3
-O(4).  The O(3) and O(5) atoms are also ?
3
 
because the VO
5
 unit utilizes O(3) and O(5) to edge-share or corner-share with either a 
ThO
9
 tricapped trigonal prism or a TeO
6
 octahedron.  A depiction of these complex 
combinations is shown in Figure 4.2a. 
The tetrahedral VO
4
 units containing V(2) are distorted from ideality.  The bond 
distances observed within the vanadyl unit of VO
4
 tetrahedron are similar to those found 
within VO
5
 unit with a distance of 1.654(5) ? to both O(6) and O(7), and a bond angle of 
111.2(3)?.  The remaining V?O bond lengths are V(2)?O(8) at 1.771(4) ?, and V(2)?
O(9) at 1.801(4) ?.  The bond angles range from 105.3(2)? to 119.2(2)?.  The VO
4
 units 
only corner-share with adjacent polyhedra, leaving all oxygen atoms as bridging: O(6) 
and O(7) to Th(1) and O(8) and O(9) to Te(1).  A view of these interactions is shown in 
Figure 4.2b. 
       
Figure 4.2.  a) A depiction of the interactions between the VO
5
 distorted square pyramids 
and neighboring polyhedra in Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
.  Edge-sharing occurs with one 
ThO
9
 unit and one TeO
6
 unit.  Corner-sharing occurs with two additional ThO
9
 tricapped 
trigonal prisms and one TeO
6
 octahedron.  b) The VO
4
 units corner-share with two ThO
9
 
units and two TeO
6
 units.  Vanadium polyhedra are shown in magneta, thorium in green, 
and tellurium in blue.  
94 
95 
 The tellurate anions, containing Te(VI), are highly distorted from idealized 
octahedral symmetry with Te?O bond distances ranging from 1.829(4) to 1.953(4) ?.  
The distortion is approximately tetragonal in nature and is in the direction of O(10), this 
being the shortest Te?O bond distance of 1.829(4) ?.  The O?Te?O bond angles given in 
Table 4.2 also demonstrate the deviation of the tellurate anion from octahedral symmetry.  
The TeO
6
6?
 anion utilizes all of its oxygen atoms to bond to adjacent polyhedra with one 
edge-sharing interaction with a ThO
9
 unit and another with a VO
5
 unit.  Corner-sharing 
interactions also occur with two ThO
9
, one VO
5
, and two VO
4
 polyhedra as shown in 
Figure 4.3.  These bonds result in three ?
2
-O atoms (O(3), O(4), and O(5)) as well as 
three ?
3
-O atoms (O(8), O(9), and O(10)).   
The triad that forms from the ThO
9
, VO
5
, and TeO
6
 through edge-sharing is the 
essential building block of part of the structure of Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
.  These units 
form a continuum of edge-sharing interactions to create Th-V-Te oxide chains, which 
extend along the b-axis as shown in Figure 4.4.  Corner-sharing interactions between the 
TeO
6
 and VO
5
 units and the Th centers of adjacent chains lead to the formation of two-
dimensional sheets in the [ab] plane.  The three-dimensional network is formed by the 
linkage of these sheets through the VO
4
 units, as in shown in Figure 4.5.  The VO
4
 
tetrahedra bridge the Th and Te centers from one sheet to thorium and tellurium in an 
adjacent sheet in the c direction. 
Optical Properties.   The optical properties of Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
 have been 
evaluated using UV-vis diffuse reflectance spectroscopy (Figure 4.6).  This compound 
displays a weak absorption band near 387 nm that is followed by strong absorption at 
approximately 600 nm.  The spectrum is similar that of other vanadyl oxoanion  
 
 
                       
 
 
 
 
Figure 4.3.  An illustration of the bonding for the tellurate, TeO
6
6?
, anion in 
Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
.  All six oxygen atoms are used to bind neighboring metal centers 
resulting in two edge-sharing interactions with a ThO
9
 unit and one with a VO
5
 unit.  
Corner-sharing interactions also occur with one ThO
9
, one VO
5
, and two VO
4
 polyhedra.  
Vanadium polyhedra are shown in magenta, thorium in green, and tellurium in blue. 
96 
 
    
 
 
            
 
 
 
 
Figure 4.4.  A view of the ThO
9
, VO
5
, and TeO
6
 units that form a continuum of edge-
sharing interactions to yield Th-V-Te oxide chains that extends along the b-axis.  Corner-
sharing interactions between TeO
6
 and VO
5
 units and the Th centers of adjacent chains 
form two-dimensional sheets in the [ab] plane.   
97 
 
 
 
 
       
 
 
 
 
 
98 
Figure 4.5.  The three-dimensional network of Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
 is formed by the 
linkage of these sheets through the VO
4
 units.  The VO
4
 tetrahedra bridge the Th and Te 
centers from one sheet to thorium and tellurium in an adjacent sheet in the c direction.  
Vanadium polyhedra are shown in magenta, thorium in green, and tellurium in blue. 
 
 
 
 
 
 
 
Figure 4.6.  The diffuse reflectance absorbance spectrum of Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
 
featuring a weak absorption band near 387 nm that is followed by strong absorption 
feature at approximately 600 nm. 
99 
100 
compounds such as A[VO
2
(IO
3
)
2
] (A = K, Rb) and A[(VO)
2
(IO
3
)
3
O
2
] (A = NH
4
, Rb, 
Cs).
19
  It is likely that the visible absorption for Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
 can be attributed 
to charge-transfer in the vanadyl units. 
 Thermal Behavior.  Differential scanning calorimetry measurements on 
Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
 show that the compound is stable to approximately 250 ?C, 
thereafter it begins to lose water with an endotherm centered at 282 ?C.  This is followed 
by further decomposition with three endotherms at 418, 456, and 472 ?C following by a 
small exotherm at 534 ?C.  TGA measurements show that the endotherm near 456 ?C is 
associated with the loss of Te from the sample (Figure 4.7).  Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
 
decomposes primarily to Th(VO
3
)
4
 when heated at 600 ?C in air as determined by X-ray 
powder diffraction measurements.
20
 
 
CONCLUSIONS 
 The synthesis of the first actinide tellurate, Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
, has been 
achieved via the hydrothermal reaction of Th(NO
3
)
4
?xH
2
O with V
2
O
5
 and H
6
TeO
6
.  The 
remarkably complex three-dimensional structure of Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
 is a direct 
consequence of the high coordination number of Th combined with the variable 
coordination of vanadium and the remarkable ability of tellurate to simultaneously bind 
seven metal centers.  This first example of a thorium tellurate points to what is likely to 
be a large family of structurally diverse actinide tellurate compounds.  
 
 
 
 
 
 
 
 
-0.02
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0 100 200 300 400 500 600 700 800
Tempurature (C)
 
 
 
 
 
Figure 4.7.  Thermogravimetric analysis of Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
 shows that the 
endotherm centered around 456 ?C is due to a loss of Te, which is confirmed by X-ray 
powder diffraction.  
101 
102 
Table 4.3.  Atomic Coordinates and Equivalent Isotropic Displacement Parameters for 
Th(VO
2
)
2
(TeO
6
)(H
2
O)
2
. 
Atom x y z U
eq 
(?
2
)
a
 
Th1 0.156268(15) 0.065122(17) 0.175256(15) 0.00954(7) 
Te1 -0.07545(3) 0.22523(3) 0.25827(3) 0.00934(9) 
V1 0.07358(7) 0.42168(8) 0.20293(8) 0.00947(19) 
V2 0.06217(8) -0.18383(9) -0.00118(8) 0.0151(2) 
O1 0.0589(4) 0.4391(4) 0.0804(4) 0.0243(10) 
O2 0.2011(4) 0.4446(4) 0.2274(4) 0.0188(9) 
O3 0.0266(3) 0.5690(3) 0.2583(3) 0.0106(8) 
O4 -0.0731(3) 0.3901(3) 0.2609(3) 0.0104(7) 
O5 0.0693(3) 0.2557(3) 0.2183(3) 0.0110(8) 
O6 0.1467(4) -0.0897(4) 0.0472(4) 0.0213(10) 
O7 -0.0505(4) -0.1207(4) -0.0315(4) 0.0246(10) 
O8 0.1206(3) -0.2326(4) -0.1162(3) 0.0139(8) 
O9 0.0342(3) -0.2868(3) 0.0984(3) 0.0142(8) 
O10 -0.2123(3) 0.1950(3) 0.2929(3) 0.0128(8) 
O11 0.2723(4) 0.0941(4) 0.0170(4) 0.0269(11) 
O12 0.1694(4) 0.0951(4) 0.3717(3) 0.0203(10) 
 
a
 U
eq 
is defined as one-third of the trace of the orthogonalized U
ij
 tensor. 
 
103 
REFERENCES 
1. Levason, W. Coord. Chem. Rev. 1997, 161, 33. 
2. Hector, A. L.; Hill, N. J.; Levason, W.; Webster, M. Z. Anorg. Allg. Chem. 2002, 
628, 815. 
3. Levason, W.; Oldroyd, R. D.; Webster, M. J. Chem., Dalton Trans., 1994, 20, 
2983. 
4. Levason, W.; Spicer, M. D.; Webster, M. Inorg. Chem. 1991, 30, 967. 
5. Levason, W.; Spicer, M. D.; Webster, M. J. Chem., Dalton Trans., 1988, 5, 1377. 
6. Levason, W.; Webster, M. Acta Crystallogr. 1998, C54, 1729. 
7. Sullens, T. A.; Jensen, R. A.; Shvareva, T. Y.; Albrecht-Schmitt, T. E. J. Am. 
Chem. Soc. 2004, 126, 2676. 
8. Sykora, R. E.; Albrecht-Schmitt, T. E. Inorg. Chem. 2003, 42, 2179. 
9. Ok, K. M.; Halasyamani, P. S. Solid State Sci. 2002, 4, 793.  
10. Yu, R.; Ok, K. M.; Halasyamani, P. S. J. Chem., Dalton Trans., 2004, 3, 392. 
11. Wendlandt, W. W.; Hecht, H. G.: Reflectance Spectroscopy. Interscience 
Publishers, New York, 1966.  
12. Sheldrick, G. M. SHELXTL PC, Version 6.12, An Integrated System for Solving, 
Refining, and Displaying Crystal Structures from Diffraction Data; Siemens 
Analytical X-Ray Instruments, Inc.: Madison, WI 2001. 
13. Sheldrick, G. M. SADABS 2001, Program for absorption correction using SMART 
CCD based on the method of Blessing: Blessing, R. H. Acta Crystallogr. 1995, 
A51, 33. 
14. Bean, A. C.; Peper, S. M.; Albrecht-Schmitt, T. E. Chem. Mater. 2001, 13, 1266. 
104 
15. Hector, A. L.; Henderson, S. J.; Levason, W.; Webster, M. Z. Anorg. Allg. Chem. 
2002, 628, 198. 
16. Douglas, P.; Hector, A. L.; Levason, W.; Light, M. E.; Matthews, M. L.; Webster, 
M. Z. Anorg. Allg. Chem. 2004, 630, 479. 
17. Brown, I. D.; Altermatt, D. Acta Crystallogr. 1985, B41, 244. 
18. Brese, N. E.; O?Keeffe, M. Acta Crystallogr. 1991, B47, 192. 
19. Sykora, R. E.; Ok, K. M.; Halasyamani, P. S.; Wells, D. M.; Albrecht-Schmitt, T. 
E. Chem. Mater. 2002, 14, 2741. 
20. Quarton, M.; Pages, M.; Freundlich, W. Comp. Ren. Sean. Acad. Sci., Serie C: 
Sci. Chim. 1978, 286, 369-71.   
105 
Chapter 5 
CATION-CATION INTERACTIONS BETWEEN URANYL CATIONS IN A 
POLAR OPEN-FRAMEWORK URANYL PERIODATE 
 
ABSTRACT 
Novel open-framework alkali metal and silver uranyl periodates, having the 
formula A[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (A = Li, Na, K, Rb, Cs, Ag), have been 
prepared through mild hydrothermal synthesis.  These isostructural compounds contain 
distorted UO
7
 pentagonal bipyramids that are linked through a uranyl (UO
2
2+
) to uranyl 
cation-cation interaction.  This interaction arises from a single axial uranyl oxygen 
coordinating at an equatorial site of an adjacent uranyl unit.  These uranium oxide 
polyhedra are further bound by IO
6
 distorted octahedra creating an open-framework 
structure whose channels contain the alkali metal cations.   
 
INTRODUCTION 
Cation-cation interactions (CCI?s) are an integral part of both the solution and 
solid-state chemistry of AnO
2
+
 (An = U, Np, Pu, Am) cations, which contain actinides in 
+V oxidation state.
1
  These interactions occur via coordination of one actinide metal 
center by the oxo atom of a second actinyl unit, and can lead to the formation of dimers, 
oligomers, one-dimensional chains, two-dimensional sheets, and even three-dimensional 
106 
networks that do not necessarily require the support of ancillary ligands.
1,2
  These 
interactions are particularly well recognized for Np(V),
3
 but have also been identified in 
U(V),
4
 Pu(V),
5
 and Am(V) chemistry.
6
  CCI?s play a critical role in the inner-sphere 
electron transfer that leads to the disproportionation of U(V) into U(VI) and U(IV),
4
 and 
in interactions in Np(V) compounds that give rise to Ising-type ferromagnetic and 
metamagnetic behavior.
7
  CCI?s are rare in compounds that exclusively contain U(VI) in 
the form of uranyl cations (hereafter uranyl refers to the UO
2
2+
 cation).
8
  However, in 
condensed phases UO
2
2+
 cations are known to interact with alkali and alkaline earth 
metal cations.
9
  Due to the isostructural nature of these compounds, 
Cs[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O will be used in the forthcoming description and 
characterizations of these structures. 
 
EXPERIMENTAL 
Syntheses.  Li
2
CO
3
 (Alpha Aesar), Na
2
CO
3
 (Alpha Aesar), K
2
CO
3
 (Alpha Aesar), 
Rb
2
CO
3
 (Alpha Aesar), Cs
2
CO
3
 (Alpha Aesar), Ag
2
CO
3
 (Alpha Aesar), 
UO
2
(NO
3
)
2
?6H
2
O (216 mg, 0.431 mmol), H
5
IO
6
 (116 mg, 0.509 mmol) were used as 
received.  Distilled and Millipore-filtered water was used in all reactions.  The resistance 
of the water was 18.2 M??cm.  The PTFE liners used to contain these reactions were 
cleaned of contaminants by heating with distilled and Millipore filtered water at 200 ?C 
for 3 d prior to use.  While the UO
3
 contains depleted U, standard precautions for 
handling radioactive materials should be followed.  Old sources of depleted U should not 
be used, as the daughter elements of natural decay are highly radioactive and present 
serious health risks.   SEM/EDX analyses were performed using a JEOL 840/Link Isis 
107 
instrument.  The reported preparations given herein are taken from a modified 
compositional diagram and represent the highest yields of pure phases obtained where 
possible.   
Li[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (1).  Li
2
CO
3
 (46 mg, 0.629 mmol), 
UO
2
(NO
3
)
2
?6H
2
O (312 mg, 0.621 mmol), and H
5
IO
6
 (142 mg, 0.624 mmol) were loaded 
into a 23 mL PTFE-lined autoclave.  Millipore-filtered water (1.5 mL)was then added to 
the reaction mixture.  The autoclave was heated at 185 ?C for 120 h and slow cooled at 5 
?C/h to 135 ?C where it was held for 12 h.  After this the autoclave was cooled at 5 ?C/h 
to 22 ?C.  Yellow prisms of 1 were isolated in 86% yield based on uranium (583 mg).  
Crystals were shown to contain Li, U, and I in a 1:3:1 ratio as determined from semi-
quantitative EDAX measurements. 
 Na[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (2).  Na
2
CO
3
 (63 mg, 0.599 mmol), 
UO
2
(NO
3
)
2
?6H
2
O (300 mg, 0.599 mmol), and H
5
IO
6
 (136 mg, 0.597 mmol) were loaded 
into a 23 mL PTFE-lined autoclave.  Millipore-filtered water (1.5 mL) was then added to 
the reaction mixture.  The autoclave was heated at 185 ?C for 120 h and slow cooled at 5 
?C/h to 135 ?C where it was held for 12 h.  After this the autoclave was cooled at 5 ?C/h 
to 22 ?C.  Yellow prisms of 2 were isolated in 73% yield based on uranium (484 mg).  
Crystals were shown to contain Na, U, and I in a 1:3:1 ratio as determined from semi-
quantitative EDAX measurements. 
 K[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (3).  K
2
CO
3
 (80 mg, 0.574 mmol), 
UO
2
(NO
3
)
2
?6H
2
O (289 mg, 0.577 mmol), and H
5
IO
6
 (131 mg, 0.576 mmol) were loaded 
into a 23 mL PTFE-lined autoclave.  Millipore-filtered water (1.5 mL) was then added to 
the reaction mixture.  The autoclave was heated at 185 ?C for 120 h and slow cooled at 5 
108 
?C/h to 135 ?C where it was held for 12 h.  After this the autoclave was cooled at 5 ?C/h 
to 22 ?C.  Yellow prisms of 3 were isolated in 89% yield based on uranium (577 mg).  
Crystals were shown to contain K, U, and I in a 1:3:1 ratio as determined from semi-
quantitative EDAX measurements. 
 Rb[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (4).  Rb
2
CO
3
 (120 mg, 0.520 mmol), 
UO
2
(NO
3
)
2
?6H
2
O (261 mg, 0.521 mmol), and H
5
IO
6
 (118 mg, 0.521 mmol) were loaded 
into a 23 mL PTFE-lined autoclave.  Millipore-filtered water (1.5 mL) was then added to 
the reaction mixture.  The autoclave was heated at 185 ?C for 120 h and slow cooled at 5 
?C/h to 135 ?C where it was held for 12 h.  After this the autoclave was cooled at 5 ?C/h 
to 22 ?C.  Yellow prisms of 4 were isolated in 82% yield based on uranium (499 mg).  
Crystals were shown to contain Rb, U, and I in a 1:3:1 ratio as determined from semi-
quantitative EDAX measurements. 
Cs[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (5). Cs
2
CO
3
 (154 mg, 0.473 mmol), 
UO
2
(NO
3
)
2
?6H
2
O (238 mg, 0.473 mmol), and H
5
IO
6
 (108 mg, 0.475 mmol) were loaded 
into a 23 mL PTFE-lined autoclave.  Millipore-filtered water (1.5 mL) was then added to 
the reaction mixture.  The autoclave was heated at 185 ?C for 120 h and slow cooled at 5 
?C/h to 135 ?C where it was held for 12 h.  After this the autoclave was cooled at 5 ?C/h 
to 22 ?C.  Yellow prisms of 5 were isolated in 91% yield based on uranium (523 mg).  
Crystals were shown to contain Cs, U, and I in a 1:3:1 ratio as determined from semi-
quantitative EDAX measurements. 
Ag[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (6).  Ag
2
CO
3
 (137 mg, 0.496 mmol), 
UO
2
(NO
3
)
2
?6H
2
O (250 mg, 0.497 mmol), H
5
IO
6
 (113 mg, 0.498 mmol) were loaded into 
a 23 mL PTFE-lined autoclave.  Millipore-filtered water (1.5 mL) was then added to the 
109 
reaction mixture.  The autoclave was heated at 185 ?C for 120 h and slow cooled at 5 
?C/h to 135 ?C where it was held for 12 h.  After this the autoclave was cooled at 5 ?C/h 
to 22 ?C.  Yellow prisms of 6 were isolated in 85% yield based on uranium (503 mg).  
Crystals were shown to contain Ag, U, and I in a 1:3:1 ratio as determined from semi-
quantitative EDAX measurements. 
X-ray structural analysis.  Li[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (1): 
yellow prism, dimensions 0.192 x 0.048 x 0.048 mm, monoclinic, Cc, Z = 4, a = 
13.087(1), b = 10.120(1), c = 11.119(1) ?, ? = 102.229(2)?, V = 1439.1(3) ?
3 
(T = 193 
K), ? = 359.04 cm
-1
, R
1
 = 0.0444, wR2 = 0.0980.
15
  Bruker APEX CCD diffractometer: 
?
max
 = 56.62?, MoK?, ? = 0.71073 ?, 0.3? ? scans, 7227 reflections measured, 3464 
independent reflections, all of which were included in the refinement.  The data were 
corrected for Lorentz-polarization effects and for absorption (analytical and SADABS).  
The structure was solved by direct methods, followed by a refinement of F
2
 by full-
matrix least-squares with 181 parameters.
15
  Anisotropic displacement parameters were 
included for all heavy atoms and most oxygen atoms.   
Na[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (2): yellow prism, dimensions 0.120 x 
0.064 x 0.050 mm, monoclinic, Cc, Z = 4, a = 13.093(2), b = 10.0755(7), c = 11.034(2) 
?, ? = 102.073(2)?, V = 1428.0(5) ?
3 
(T = 193 K), ? = 332.59 cm
-1
, R
1
 = 0.0549, wR2 = 
0.1223.
15
  Bruker APEX CCD diffractometer: ?
max
 = 56.54?, MoK?, ? = 0.71073 ?, 0.3? 
? scans, 7364 reflections measured, 3485 independent reflections, all of which were 
included in the refinement.  The data were corrected for Lorentz-polarization effects and 
for absorption (analytical and SADABS).  The structure was solved by direct methods, 
followed by a refinement of F
2
 by full-matrix least-squares with 181 parameters.
15
  
110 
Anisotropic displacement parameters were included for all heavy atoms and most oxygen 
atoms.   
K[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (3): yellow prism, dimensions 0.258 x 
0.042 x 0.040 mm, monoclinic, Cc, Z = 4, a = 13.009(1), b = 10.1144(9), c = 11.152(1) 
?, ? = 102.289(2)?, V = 1433.7(2) ?
3 
(T = 193 K), ? = 363.34 cm
-1
, R
1
 = 0.0367, wR2 = 
0.0892.
15
  Bruker APEX CCD diffractometer: ?
max
 = 56.54?, MoK?, ? = 0.71073 ?, 0.3? 
? scans, 6976 reflections measured, 3383 independent reflections, all of which were 
included in the refinement.  The data were corrected for Lorentz-polarization effects and 
for absorption (analytical and SADABS).  The structure was solved by direct methods, 
followed by a refinement of F
2
 by full-matrix least-squares with 181 parameters.
15
  
Anisotropic displacement parameters were included for all heavy atoms and most oxygen 
atoms.   
Rb[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (4): yellow prism, dimensions 0.098 x 
0.034 x 0.028 mm, monoclinic, Cc, Z = 4, a = 13.231(3), b = 10.095(2), c = 11.150(3) ?, 
? = 103.003(4)?, V = 1451.1(6) ?
3 
(T = 193 K), ? = 389.34 cm
-1
, R
1
 = 0.0513, wR2 = 
0.1120.
15
  Bruker APEX CCD diffractometer: ?
max
 = 56.54?, MoK?, ? = 0.71073 ?, 0.3? 
? scans, 7133 reflections measured, 3579 independent reflections, all of which were 
included in the refinement.  The data were corrected for Lorentz-polarization effects and 
for absorption (analytical and SADABS).  The structure was solved by direct methods, 
followed by a refinement of F
2
 by full-matrix least-squares with 181 parameters.
15
  
Anisotropic displacement parameters were included for all heavy atoms and most oxygen 
atoms.   
111 
Cs[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (5): yellow prism, dimensions 0.070 x 
0.052 x 0.048 mm, monoclinic, Cc, Z = 4, a = 13.0960(9), b = 10.0714(7), c = 11.0398(8) 
?, ? = 102.064(1)?, V = 1421.0(2) ?
3 
(T = 193 K), ? = 388.78 cm
-1
, R
1
 = 0.0239, wR2 = 
0.0478.
15
  Bruker APEX CCD diffractometer: ?
max
 = 56.54?, MoK?, ? = 0.71073 ?, 0.3? 
? scans, 7026 reflections measured, 3447 independent reflections, all of which were 
included in the refinement.  The data were corrected for Lorentz-polarization effects and 
for absorption (analytical and SADABS).  The structure was solved by direct methods, 
followed by a refinement of F
2
 by full-matrix least-squares with 181 parameters.
15
  
Anisotropic displacement parameters were included for all heavy atoms and most oxygen 
atoms.   
Ag[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (6): yellow prism, dimensions 0.124 x 
0.040 x 0.038 mm, monoclinic, Cc, Z = 4, a = 13.220(3), b = 9.566(2), c = 10.999(2) ?, ? 
= 102.43(3)?, V = 1358.3(5) ?
3 
(T = 193 K), ? = 394.35 cm
-1
, R
1
 = 0.0548, wR2 = 
0.1098.
15
  Bruker APEX CCD diffractometer: ?
max
 = 56.54?, MoK?, ? = 0.71073 ?, 0.3? 
? scans, 6989 reflections measured, 3287 independent reflections, all of which were 
included in the refinement.  The data were corrected for Lorentz-polarization effects and 
for absorption (analytical and SADABS).  The structure was solved by direct methods, 
followed by a refinement of F
2
 by full-matrix least-squares with 181 parameters.
15
  
Anisotropic displacement parameters were included for all heavy atoms and most oxygen 
atoms.   
Ion-exchange analysis.  Ion exchange properties were also investigated under 
three methods, all involving a ten-fold excess (in total) of alkali chloride salts in solution 
to establish exchange with either 2, 3, 4, or 6.  The first method involved heating the 
112 
solution to 50 ?C with the solid for 3 d. The second had the solution held constant at room 
temperature for 14 d.  The final method had 2 in solution at 120 ?C for 3 d.  All semi-
quantitative exchange values were measured with either Cs
+
 selective electrodes or by 
EDAX analysis.  
 
Results and Discussion  
Synthesis.  In an effort to expand solid state-studies on uranyl periodate
10
 
compounds beyond the single known example of K
2
[(UO
2
)
2
(VO)
2
(IO
6
)
2
O]?H
2
O,
11
 we 
have explored the hydrothermal reactions of alkali metal and silver carbonates with 
uranyl nitrate and periodic acid at 185 ?C.  These reactions result in the formation of 
A[(UO
2
)
3
(HIO
6
)
2
(OH)(O)(H
2
O)]?1.5H
2
O (A = Li(1) ? Cs(5), Ag(6)) in yields as high as 
91%.  The primary difficulty in this synthetic procedure is slowing the reduction of the 
I(VII) to I(V), which results in the formation of UO
2
(IO
3
)
2
(H
2
O).
12
  Compounds 1?6 are 
isolated as lemon yellow prisms from a colorless mother liquor.  The IR vibrational 
spectra of these compounds show a characteristic ?(IOH) mode near 1071 cm
-1
,
10
 as well 
as strong uranyl symmetric and asymmetric modes.   
Structure.  Cs[(UO
2
)
3
(HIO
6
)
2
(OH)(O)(H
2
O)]?1.5H
2
O.  Single crystal X-ray 
diffraction studies (Table 5.1-3) on 1-6 reveal that all of the compounds are isostructural 
and crystallize in the polar monoclinic space group Cc.  The structure of 5, which will be 
used to represent all six compounds, results from the assembly of three 
crystallographically unique uranyl units that are bridged by aquo, hydroxo, oxo, and 
monoprotonated periodate groups to yield a remarkably complex three-dimensional 
 
Table 5.1.  Crystallographic data for A[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (A = Li(1), 
Na(2)).
19
 
Compound 1 2 
Formula mass 1117.05 1135.00 
Crystal system Monoclinic Monoclinic
Space group Cc (No. 9) Cc (No. 9) 
a (?) 13.0874(14) 13.093(2)
b (?) 10.1197(11) 10.0755(7) 
c (?) 11.1186(12) 11.034(2)
? (deg.) 90 90 
? (deg.) 102.229(2) 102.073(2) 
? (deg.) 90 90
V (?
3
) 1439.1(3) 1428.0(5) 
Z 4 4
T (?C) ?80 ?80 
? (?) 0.71073 0.71073
?
calcd
 (g cm
?3
) 5.711 5.723 
? (Mo K?, cm
?1
) 359.04 332.59
R(F) for F
o
2
 > 2?(F
o
2
) 
a
 0.0444 0.0548 
R
w
(F
o
2
) 
b
 0.0980 0.1223
a
 
()
RF F F F=???
oc o
.  
b
 
() ( )
RF wF F wF
wo
2
o
2
c
2
2
o
4
12
=?
?
?
?
?
?
?
??
?
?
?
?
?
?
 
113 
Table 5.2.  Crystallographic data for A[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (A = K(3), 
Rb(4)).
19
 
Compound 3 4 
Formula mass 1117.05 1135.00 
Crystal system Monoclinic Monoclinic
Space group Cc (No. 9) Cc (No. 9) 
a (?) 13.0090(10) 13.231(3) 
b (?) 10.1144(9) 10.095(2)
c (?) 11.1520(10) 11.150(3) 
? (deg.) 90 90
? (deg.) 102.289(2) 103.003(4) 
? (deg.) 90 90 
V (?
3
) 1433.7(2) 1451.1(6) 
Z 4 4
T (?C) ?80 ?80 
? (?) 0.71073 0.71073
?
calcd
 (g cm
?3
) 5.342 5.384 
? (Mo K?, cm
?1
) 363.34 389.34
R(F) for F
o
2
 > 2?(F
o
2
) 
a
 0.0367 0.0513 
R
w
(F
o
2
) 
b
 0.0892 0.1120
a
 
()
RF F F F=???
oc o
.  
b
 
() ( )
RF wF F wF
wo
2
o
2
c
2
2
o
4
12
=?
?
?
?
?
?
?
??
?
?
?
?
?
?
 
114 
Table 5.3.  Crystallographic data for A[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (A = Cs(5), 
Ag(6)).
 19
 
Compound 5 6 
Formula mass 1221.90 1204.86 
Crystal system Monoclinic Monoclinic 
Space group Cc (No. 9) Cc (No. 9) 
a (?) 13.0960(9) 13.220(3) 
b (?) 10.0714(7) 9.566(2) 
c (?) 11.0398(8) 10.999(2)
? (deg.) 90 90 
? (deg.) 
102.604(1) 102.43(3) 
? (deg.) 90 90 
V (?
3
) 1421.0(2) 1358.3(5) 
Z 4 4
T (?C) 
?80 ?80 
? (?) 
0.71073 0.71073 
?
calcd
 (g cm
?3
) 
5.711 5.892
? (Mo K?, cm
?1
) 
388.78 394.35 
R(F) for F
o
2
 > 2?(F
o
2
) 
a
 
0.0239 0.0548
R
w
(F
o
2
) 
b
 0.0478 0.1098 
a
 
()
RF F F F=???
oc o
.  
b
 
() ( )
RF wF F wF
wo
2
o
2
c
2
2
o
4
12
=?
?
?
?
?
?
?
??
?
?
?
?
?
?
 
115 
116 
structure with intersecting channels extending along the c axis and approximately down 
110 and 1-10, as shown in Figures 5.1 and 5.2.  Three-dimensional uranyl compounds are 
uncommon because uranyl polyhedra typically align in a parallel fashion, and given the 
terminal nature of the oxo atoms, layered architectures result.
13,14
  Alkali metal cations 
and water molecules fill the channels, which as can be seen in Figure 5.1 are also polar.  
The structure is apparently quite rigid and the channels show almost no measurable size 
variance with reduction in the size of the alkali metal cations.  However, the displacement 
parameters for the cations smaller than Rb
+
 do show considerable enlargement 
corresponding to rattling within the confines of the channels.  This rattling does not result 
in splitting or disorder of the alkali metal cation position.  However, in the case of 1, the 
Li
+
 cation had to be refined isotropically owing to the large motion of this cation within 
the channel. 
Each of the three uranyl units in 5 is coordinated by five oxygen atoms in the 
equatorial plane to yield [UO
7
] pentagonal bipyramids.  The uranyl U=O distances for 
U(1) and U(2) are normal and range from 1.769(8) to 1.781(7) ?.  The equatorial U-O 
distances are also within normal limits and occur from 2.181(7) to 2.581(6) ?.  The 
shortest U?O bond length in the equatorial plane is to the ?
3
-oxide ion.  The uranyl unit 
for U(3) has U=O distances of 1.829(7) and 1.793(8) ?.  The former U=O distance does 
not correspond to a typical terminal uranyl oxo atom (Figure 5.3), but rather this atom is 
bridging to a neighboring uranyl unit containing U(1).  This bridging distance is within 
typical limits for donor atoms in the equatorial plane with a distance of 2.379(7) ?, as 
depicted in Figure 5.4.  This interaction effectively turns uranyl polyhedra perpendicular 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
O(8)
O(10)
O(15)
O(2)
O(12)
O(3)
O(4)
O(1)
O(5)
O(7)
O(9)
O(1)?
O(14)
O(4)?
O(13)
O(11)
O(8)
O(5)?
O(15)?
O(4)?
O(14)?
O(7)?
O(6)?
O(12)?
O(8)?
O(6)
I(1) U(1)
U(2)
U(3)
U(1)?
 
 
 
 
Figure 5.1.  Thermal ellipsoid plot of Cs[(UO
2
)
3
(HIO
6
)
2
(OH)(O)(H
2
O)]?1.5H
2
O at 50% 
probability.  O(15)? acts as both a coordinating equatorial oxygen atom to U(1) and an 
oxo-atom of the U(3) uranyl (UO
2
2+
) unit.  This dual role is the basis of the cation-cation 
interaction between U(1) and U(3).  Cs
+
 is eliminated for clarity. 
117 
 
 
 
 
Figure 5.2.  A view down the c axis showing the polar open-framework structures of 
A[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (Li(1)-Cs(5)).  The major channels running 
down this axis are filled with alkali metal cations.  UO
7
 pentagonal bipyramids are shown 
in green and IO
6
 octahedra in blue. 
118 
 
 
 
 
 
 
2.364(8) ? 
1.846(8) ?
1.78(1) ?
 
 
 
 
 
 
Figure 5.3.  An illustration of the cation-cation interaction between the uranyl unit 
containing U(3) and the uranyl cation containing U(1).  The slight elongation of the 
uranyl bond length between the dual role oxygen atom and the lower uranium atom is 
also evident. 
119 
120 
to one another creating two orthogonal uranium oxide sheets within the structure.  This is 
best viewed in Figure 5.2, thereby leading to a three-dimensional architecture.  Bond-
valence sum calculations confirm that these three uranium centers are unambiguously 
U(VI) with values of 6.06, 6.00, and 6.12 for U(1), U(2), and U(3), respectively.
15-17
  This 
is a rare example of cation-cation interactions between uranyl cations, and it provides a 
structural link between the CCI?s in AnO
2
+
 compounds and those that contain UO
2
2+
.
8
 
The question then arises: what makes U(3) so different from U(1) and U(2) to 
make the normally terminal uranyl cation form a cation-cation interaction more similar to 
that expected for an AnO
2
+
 cation instead of UO
2
2+
?  A close look at the individual 
coordination environments of the uranium centers reveals that U(2) and U(3) are chelated 
by the HIO
6
4?
 anion.  This anion also utilizes its oxo atoms to bridge to an additional four 
uranium centers.  The hydrogen periodate anion has five I?O bond distances ranging 
from 1.830(7) to 1.894(7) ? and a sixth longer I?O(H) bond length of 1.926(8) ? to the 
nominal hydroxo group.  We suggest that through the chelation of U(3) by the hydrogen 
periodate anion that significant electron density is transferred from this highly charged 
anion to the U(3) uranyl cation to make the oxo atoms better Lewis bases than is typically 
found.  We cannot exclude the possibility that this interaction is a consequence of other 
features of this structure, especially crystal packing forces. 
The transfer of charge from the U(3) uranyl unit to an adjacent uranyl cation 
should result in a strengthening of the interactions with the donor atoms in the equatorial 
plane.  The converse of which is that stronger equatorial bonds results in the formation of  
CCI?s.  Unfortunately, the ligand environments for each U center are different, making 
 
 
  
Figure 5.4.  A view of A[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (Li(1)-Cs(5)) showing 
the second type of channel that intersects with the channels running down the c axis to 
yield an open-framework structure. 
121 
122 
comparisons difficult.  However, the average U?O distance to equatorial atoms 
surrounding U(3) is 2.322(7) ?, whereas statistically longer U?O distances of 2.377(7) ? 
and 2.389(7) ? are observed for U(1) and U(2), respectively.  In a recent, and quite 
timely, report by Sarsfield and Helliwell, it was shown that uranyl coordination 
compounds could be rationally prepared that have uranyl oxo atoms of increased Lewis 
basicity.
18
  These oxo atoms are of sufficient basicity to form adducts with B(C
6
F
5
)
3
.  The 
charge transfer that results from the formation of this adduct also coincides well with the 
lengthening of the uranyl oxo distances and shortening the average bond length in the 
equatorial plane of this complex.     
There is a difference in one fundamental aspect of the crystal structure between 
the alkali- and silver-containing compounds.  As illustrated in the text as well as the 
figures of 1-5, the channels are filled with the alkali metal cation.  The structure of 6 
reveals the silver cation and the hydrating water molecule actually change places within 
the gaps formed in the structure (Figure 5.5).  One, and perhaps the only, explanation for 
this occurrence is the ability of silver to participate in covalent bonding.  As seen in 
Figures 5.5, the silver cation is closer to the surrounding structure by occupying the 
hydrating water site rather than the alkali metal cation site.  In 5 Cs(1) maintains long 
range interactions with ten oxygen atoms with an average distance of 3.264 ?.  Silver in 
6 however has but three interactions to neighboring oxygen atoms, but these interactions 
are 2.490, 2.415, and 2.446 ? in length for an average Ag?O distance of 2.450 ?.  This 
silver-oxygen association also exists in a distorted trigonal planar linkage with the 
distortion coming primarily from the existing framework surrounding the silver cation.  
The hydrating water molecule in 6 occupies the prominent position in the center of the  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 5.5.  An illustration of the difference in location of the counter cation between the 
alkali (top) and the silver (bottom) analogues of 
Ag[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (A = Li(1)?Cs(5), Ag(6)).  The Cs
+
 analogue is 
depicted as the representative of the alkali series. 
123 
124 
channel running along the c-axis.  No other structural variations are present between the 
alkali and silver analogues of A[(UO
2
)
3
(HIO
6
)
2
(OH)(O)(H
2
O)]?1.5H
2
O (A = Li(1) ? 
Cs(5), Ag(6)).   
Ion-exchange.  The ion-exchange capabilities of these compounds were 
examined using a combination of EDAX measurements on the solids as well as Cs
+
-
selective electrodes of the solutions for Cs
+
-exchange reactions.  These results were 
compared with those obtained from K
2
[(UO
2
)
2
(VO)
2
(IO
6
)
2
O]?H
2
O, which also possesses 
a three-dimensional structure with large channels occupied by K
+
 cations.  At 22 ?C, the 
exchange of Na
+
 in 2 for larger alkali metal cations is slow and equilibrium was not 
established after two weeks.  However, the complete exchange of Na
+
 for Cs
+
 can be 
accomplished at 120 ?C in three days.  Competing ion-exchange reactions were also 
carried out whereby 2 was stirred with a tenfold excess of K
+
, Rb
+
, and Cs
+
.  These 
reactions revealed a 3.9:1.3:1 ratio of these cations in the ion-exchanged solids 
demonstrating an almost fourfold preference for the K
+
 cations over Cs
+
.  The K
+
 cations 
in K
2
[(UO
2
)
2
(VO)
2
(IO
6
)
2
O]?H
2
O can also be exchanged for Cs
+
, although this exchange 
occurs more rapidly at 22 ?C than it does for 2.  No measurable ion-exchange capabilities 
were observed by 6 due to covalent interactions of the silver cation.  Selected ion 
exchange data are available in Table 5.4. 
 
 
 
 
 
125 
Table 5.4.  Ion-exchange studies of the various analogues of 1-5.  All crystals were 
within a ten fold excess of dissolved salt solution at the indicated temperature and 
duration.  Atomic percentage was measured by EDAX analysis.  A slight selectivity for 
K
+
 over the other cations is observed.   
Crystal
a 
Salt Atomic % 
  K Rb Cs 
K[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O CsCl 72.80 n/a 1.75*
K[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O RbCl 81.90 22.95 NA 
Rb[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O CsCl n/a 65.40 54.35
    
Crystal
b
Salt Atomic % 
  K Rb Cs 
Li[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O K, Rb, CsCl 35.50 28.35 36.25
Na[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O K, Rb, CsCl 62.80 21.10 16.10
K[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O CsCl 82.50 n/a 10.30
K[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O RbCl 65.65 31.10 n/a 
Rb[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O CsCl n/a 69.30 18.60
    
Crystal
c
Salt Atomic % 
  K Rb Cs 
Na[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O CsCl n/a n/a 100 
 
a. Mixture was maintained at 50 ?C for 3 days. 
b. Mixture was maintained at 22 ?C for 14 days. 
c. Mixture was maintained at 120 ?C for 3 days. 
* Measured percentage was below EDAX error range of ?5%. 
126 
Table 5.5.  Atomic Coordinates and Equivalent Isotropic Displacement Parameters for 
Cs[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (5). 
Atom x y z U
eq
 (?
2
)
a
 
U1 0.17720(3) -0.36938(4) -0.18082(3) 0.01011(9) 
U2 0.26595(3) -0.13134(4) 0.09972(3) 0.01058(9) 
U3 0.02878(3) -0.34265(4) 0.07958(3) 0.01030(9) 
I1 0.41701(5) -0.09085(7) -0.12730(6) 0.00924(13) 
Cs1 -0.00749(6) -0.01413(7) -0.18513(7) 0.02286(17) 
O1 0.3294(6) 0.0349(7) -0.2134(7) 0.0187(17) 
O2 0.5101(6) -0.2273(7) -0.0455(7) 0.0194(18) 
O3 0.4343(6) -0.1710(7) -0.2709(6) 0.0110(14) 
O4 0.5311(6) 0.0282(7) -0.1109(7) 0.0148(16) 
O5 0.4086(5) -0.0218(7) 0.0297(6) 0.0097(15) 
O6 0.3044(6) -0.1988(7) -0.1115(6) 0.0154(17) 
O7 0.0921(6) -0.2592(7) -0.2818(7) 0.0186(18) 
O8 0.2643(6) -0.4841(8) -0.0908(7) 0.0220(18) 
O9 0.1889(6) 0.0091(7) 0.0398(7) 0.0174(17) 
O10 0.3422(6) -0.2721(8) 0.1589(7) 0.0201(18) 
O11 -0.0615(6) -0.2209(8) 0.0006(8) 0.0224(19) 
O12 0.2886(6) -0.3658(8) -0.3354(7) 0.0212(18) 
O13 0.1322(6) -0.1894(8) 0.2040(7) 0.0175(17) 
O14 0.1435(6) -0.2666(8) -0.0195(7) 0.0154(16) 
O15 0.1193(5) -0.5344(7) -0.3346(6) 0.0134(16) 
O16 0.2226(18) -0.251(2) -0.564(2) 0.050(6) 
 
a
 U
eq 
is defined as one-third of the trace of the orthogonalized U
ij
 tensor. 
127 
Table 5.6.  Atomic Coordinates and Equivalent Isotropic Displacement Parameters for 
Ag[(UO
2
)
3
(HIO
6
)(OH)(O)(H
2
O)]?1.5H
2
O (6). 
Atom x y z U
eq
 (?
2
)
a
 
U1 0.74267(9) 0.67144(12) 0.75832(9) 0.0084(2) 
U2 0.89510(8) 0.62564(12) 0.50163(8) 0.0101(3) 
U3 0.98378(8) 0.87792(12) 0.78169(8) 0.0104(3) 
I1 0.13837(14) 0.9022(2) 0.55687(15) 0.0088(4) 
Ag1 0.4508(2) 0.7347(3) 0.5905(2) 0.0279(7) 
O1 0.0117(18) 0.599(2) 0.357(2) 0.028(6) 
O2 0.8468(15) 0.8362(19) 0.8882(16) 0.009(4) 
O3 0.0318(17) 0.7820(19) 0.5811(18) 0.017(5) 
O4 0.0431(18) 0.032(2) 0.478(2) 0.026(6) 
O5 0.9256(16) 0.038(2) 0.7183(18) 0.014(5) 
O6 0.2459(17) 0.036(2) 0.5659(19) 0.015(5) 
O7 0.9710(16) 0.494(2) 0.5941(19) 0.015(5) 
O8 0.2390(15) 0.7651(18) 0.6308(18) 0.011(4) 
O9 0.1515(15) 0.825(2) 0.4100(17) 0.012(4) 
O10 0.8618(16) 0.748(2) 0.6604(18) 0.014(5) 
O11 0.8335(16) 0.548(2) 0.8463(18) 0.016(5) 
O12 0.8234(16) 0.743(2) 0.3969(18) 0.017(5) 
O13 0.1318(15) 0.9696(19) 0.7166(16) 0.006(4) 
O14 0.0426(16) 0.723(2) 0.8442(19) 0.016(5) 
O15 0.6469(16) 0.786(2) 0.6732(19) 0.014(5) 
O16 0.7129(19) 0.004(3) 0.486(2) 0.039(7) 
 
a
 U
eq 
is defined as one-third of the trace of the orthogonalized U
ij
 tensor. 
128 
REFERENCES 
1. a) Sullivan, J. C.; Hindman, J. C.; Zielen, A. J. J. Am. Chem. Soc. 1961, 83, 
3373.  b) Cousson, A.; Dabos, S.; Abazli, H.; Nectoux, F.; Pag?s, M.; Choppin, 
G. J. Less-Common Met. 1984, 99, 233.  c) Albrecht-Schmitt, T. E.; Almond, P. 
M.; Sykora, R. E. Inorg. Chem. 2003, 42, 3788. 
2. Andreev, G. B.; Budantseva, N. A.; Antipin, M. Yu. Krot, N. N. Russ. J. Coord. 
Chem. 2002, 28, 434. 
3. Krot, N. N.; Suglobov, D. N. Radiokhimiya 1989, 31, 1. 
4. Ekstrom, A. Inorg. Chem. 1974, 13, 2237. 
5. Stoyer, N. J.; Hoffman, D. C.; Silva, R. J. Radiochim. Acta 2000, 88, 279. 
6. Guillaume, B.; Hobart, D. E.; Bourges, J. Y. J. Inorg. Nucl. Chem. 1981, 43, 
3295. 
7. Nakamoto, T.; Nakada, M.; Nakamura, A.; Haga, Y.; Onuki, Y. Solid State 
Commun. 1999, 109, 77. 
8. a) Rose, D.; Chang, Y.-D.; Chen, Q.; Zubieta, J. Inorg. Chem. 1994, 33, 5167.  b) 
Thu?ry, P.; Nierlich, M.; Souley, B.; Asfari, Z.; Vicens, J. J. Chem. Soc., Dalton 
Trans. 1999, 15, 2589.  c) Taylor, J. C.; Ekstrom, A.; Randall, C. H. Inorg. Chem. 
1978, 17, 3285.  d) Brandenburg, N. P.; Loopstra, B. Acta Crystallogr. 1978, B34, 
3734. 
9. a) Zachariasen, W. H. Acta Crystallogr. 1948, 1, 281.  b) Zachariasen, W. H. Acta 
Crystallogr. 1954, 7, 788.  c) Zachariasen, W. H. Acta Crystallogr. 1954, 7, 795.  
10. Levason, W. Coord. Chem. Rev. 1997, 161, 33. 
11. Sykora R. E.; Albrecht-Schmitt, T. E. Inorg. Chem. 2003, 42, 2179. 
129 
12. Bean, A. C.; Peper, S. M.; Albrecht-Schmitt, T. E. Chem. Mater. 2001, 13, 1266. 
13. Burns, P. C.; Miller, M. L.; Ewing, R. C. Can. Mineral. 1996, 34, 845. 
14. Krivovichev, S. V.; Cahill, C. L.; Burns, P. C. Inorg. Chem. 2002, 41, 34. 
15. Burns, P. C.; Ewing, R. C.; Hawthorne, F. C. Can. Mineral. 1997, 35, 1551. 
16. Brown, I. D.; Altermatt, D. Acta Crystallogr. 1985, B41, 244. 
17. Brese, N. E.; O?Keeffe, M. Acta Crystallogr. 1991, B47, 192. 
18. Sarsfield, M. J.; Helliwell, M. J. Am. Chem. Soc. 2004, ASAP. 
19. Sheldrick, G. M. SHELXTL, Version 6.12, Bruker AXS, Inc.: Madison, WI 2001. 
 
130 
Chapter 6 
 
EXTENDED NETWORKS, POROUS SHEETS, AND CHIRAL 
FRAMEWORKS.  THORIUM MATERIALS CONTAINING MIXED 
GEOMETRY ANIONS: STRUCTURES AND PROPERTIES OF 
Th(SeO
3
)(SeO
4
), Th(IO
3
)
2
(SeO
4
)(H
2
O)
3
?H
2
O, and Th(CrO
4
)(IO
3
)
2
 
ABSTRACT   
Three novel Th(IV) compounds containing heavy oxoanions, Th(SeO
3
)(SeO
4
) 
(1), Th(IO
3
)
2
(SeO
4
)(H
2
O)
3
?H
2
O (2), and Th(IO
3
)
2
(CrO
4
) (3), have been synthesized 
under mild hydrothermal conditions.  Each of these three distinct structures contains 
trigonal-pyramidal and tetrahedral oxoanions.  Compound 1 adopts a three-
dimensional structure formed from ThO
9
 tricapped trigonal prisms, trigonal 
pyramidal selenite, SeO
3
2?
, anions containing Se(IV), and tetrahedral selenate,  
SeO
4
2?
, anions containing Se(VI).  The structure of 2 contains two-dimensional 
porous sheets and occluded water molecules.  The Th centers are found as isolated 
ThO
9
 tricapped trigonal prisms being bound by four trigonal pyramidal iodate anions, 
two tetrahedral selenate anions, and three coordinating water molecules.  In the 
structure of 3 the Th(IV) cations are found as ThO
9
 tricapped trigonal prisms.  Each 
Th center is bound by six IO
3
1?
 anions and three CrO
4
2?
 anions forming a chiral three-
131 
dimensional structure.  Second-harmonic generation of 532 nm light from 1064 nm 
radiation by a polycrystalline sample of 3 was observed.  Crystallographic data (193 
K, Mo K?, ? = 0.71073): 1; monoclinic, P2
1
/c; a = 7.0351(5) ?, b = 9.5259(7) ?, c = 
9.0266(7) ?, ? = 103.128(1), Z = 4; 2, monoclinic, P2
1
/n, a = 7.4889(9) ?, b = 
8.002(1) ?, c = 20.165(3) ?, ? = 100.142(2), Z = 4; 3, orthorhombic, P2
1
2
1
2
1
, a = 
7.3672(5) ?, b = 9.3617(6) ?, c = 11.9201(7) ?, Z = 4. 
 
INTRODUCTION 
Thorium, lacking f electrons in its normal oxidation state of +4, is ostensibly a 
rather mundane element compared to the heavier members of the series, but has 
nevertheless played a number of critical roles in actinide chemistry, particularly in 
serving as a surrogate for more radioactive elements, especially 
239
Pu(IV).
1
  Recently, 
thorium has garnered renewed interest because of its high coordination numbers, 
typically eight or nine, that give rise to rich structural chemistry.  Examples of these 
efforts include the preparation of organically templated thorium fluorides (e.g. 
[C
4
N
2
H
12
]
0.5
[ThF
5
] and [C
5
N
2
H
14
][ThF
6
]?0.5H
2
O),
2
 open-framework organic-
inorganic hybrids, such as [(Th
2
F
5
)(NC
7
H
4
O
4
)
2
(H
2
O)
2
][NO
3
],
3
 and the recent report 
from our group on the preparation of the first actinide tellurate in the form of the 
mixed-metal compound, Th(VO)
2
(TeO
6
)(H
2
O)
2
.
4
     
 Despite recent efforts in understanding the chemistry of U,
5
 Np,
6
 Pu,
7
 Am,
8
 
and Cm
9
 with oxoanions containing a nonbonding but stereochemically active lone 
pair of electrons, little is known about the structural chemistry of thorium with anions 
of this type.  This is somewhat surprising given the importance of separating and 
132 
quantifying thorium via the precipitation of its iodate salt.
10
  There have also been 
reports on the preparation and properties of thorium selenites and tellurites such as 
Th(SeO
3
)
2
?H
2
O
11
 and Th(TeO
3
)
2
,
12
 but no single-crystal X-ray diffraction data exists.  
The structure of ThTe
2
O
6
 has been solved using X-ray powder methods.
13
   
The selenite system is of particular interest because of the possibility of 
forming mixed-anion compounds containing both SeO
3
2?
 and SeO
4
2?
,
14
 which was 
recently highlighted with the report of Au
2
(SeO
3
)
2
(SeO
4
).
15
  Given the high 
coordination numbers of Th and the presence of trigonal pyramidal and tetrahedral 
anions there is also the distinct possibility that these compounds might adopt acentric 
structures.
16
  Herein we report the preparation, crystal structures, and properties of 
three Th(IV) compounds that contain both tetrahedral and trigonal pyramidal anions, 
Th(SeO
3
)(SeO
4
) (1), Th(IO
3
)
2
(SeO
4
)(H
2
O)
3
?H
2
O (2), and Th(CrO
4
)(IO
3
)
2
 (3).  The 
structures and reactivity of uranyl chromate iodates has been previously described.
17
      
 
EXPERIMENTAL 
Syntheses.  Th(NO
3
)
4
?xH
2
O (99%, Alfa-Aesar), H
5
IO
6
 (Alfa Aesar), 
Cr(NO
3
)
3
?9H
2
O (99.99%, Fisher), and H
2
SeO
4
 (40% aqueous soln., Alfa Aesar) were 
used as received.  Distilled and Millipore-filtered water with a resistance of 18.2 
M??cm was used in all reactions.  All reactions were run in PTFE-lined 23-mL Parr 
4749 autoclaves.  Standard precautions for handling radioactive materials were 
followed.  SEM/EDX analyses were performed using a JEOL 840/Link Isis 
instrument.  Typical EDX analyses are within 4% of ratios determined from single-
crystal X-ray diffraction experiments.  
133 
Th(SeO
3
)(SeO
4
) (1).  Cs
2
CO
3
 (0.171 mg, 0.526 mmol) (needed for 
crystallization to occur), Th(NO
3
)
4
?xH
2
O (252 mg, 0.526 mmol), H
2
SeO
4
 (0.33 mL, 
1.28 mmol), and 0.33 mL of water were loaded in a 23-mL PTFE-lined autoclave.  
The autoclave was sealed and placed in a preheated furnace for 4 d at 210 ?C.  The 
furnace was then cooled at 9 ?C/h to 23 ?C.  The product consisted of a colorless 
solution over clear, colorless crystals.  The major product is Th(SeO
3
)
2
.  Compound 1 
is present only in trace amounts and can be manually separated.  The crystals were 
washed with methanol and allowed to dry.  IR (KBr, cm
-1
): 943 (?, SeO
4
2?
), 911 (?, 
SeO
4
2?
), 881 (?, SeO
4
2?
), 863 (?, SeO
4
2?
), 820 (?, SeO
3
2?
), 728 (?, SeO
3
2?
), 713 (?, 
SeO
3
2?
), 530, 470 (?, SeO
3
2?
), 442 (?, SeO
3
2?
), 408 (?, SeO
4
2?
).  EDX analysis for 
Th(SeO
3
)(SeO
4
) provided a Th:Se ratio of 1:2.  
Th(IO
3
)
2
(SeO
4
)(H
2
O)
3
?H
2
O (2).  Th(NO
3
)
4
?xH
2
O (145 mg, 0.291 mmol), 
H
5
IO
6
 (69 mg, 0.302 mmol), Cr(NO
3
)
3
?9H
2
O (242 mg, 0.605 mmol), H
2
SeO
4
 (0.1 ml, 
0.389 mmol), and 1.0 mL of water were loaded in a 23-mL PTFE-lined autoclave.  
The autoclave was sealed and placed in a preheated furnace for 3 days at 210 ?C.  The 
furnace was then cooled at 9 ?C/h to 23 ?C.  The product consisted of a yellow 
solution over clear green-yellow prisms of 2 as well as undefined black and white 
powders.  The crystals were washed with methanol and allowed to dry. The yield was 
undeterminable due to the mixture of products.  IR (KBr, cm
-1
): 900 (?, SeO
4
2?
), 867 
(?, SeO
4
2?
), 853 (?, SeO
4
2?
), 817 (?, IO
3
1?
), 802 (?, IO
3
1?
), 785 (?, IO
3
1?
), 760            
(?, IO
3
1-
), 715 (?, IO
3
1?
), 600 (?, IO
3
1?
), 532 (?, IO
3
1?
).  EDX analysis for 
Th(IO
3
)
2
(SeO
4
)(H
2
O)
3
?H
2
O provided a Th:I:Se ratio of 1:2:1.  
134 
Th(CrO
4
)(IO
3
)
2
 (3).  Th(NO
3
)
4
?xH
2
O (217 mg, 0.435 mmol), H
5
IO
6
 (103 mg, 
0.451 mmol), Cr(NO
3
)
3
?9H
2
O (181 mg, 0.451 mmol), and 1.0 mL of water were 
loaded in a 23-mL PTFE-lined autoclave.  The autoclave was sealed and placed in a 
preheated furnace for 3 days at 200 ?C.  The furnace was then cooled at 9 ?C/h to 23 
?C.  The product consisted of a yellow solution over orange-yellow prisms.  Yield 
300 mg, near quantitative.  The crystals were washed with methanol and allowed to 
dry.  Phase purity was confirmed by PXRD.  EDX analysis for Th(CrO
4
)(IO
3
)
2
 
provided a Th:I:Cr ratio of 1:1:2. 
Nonlinear Optical Measurements.  Second harmonic generation (SHG) was 
investigated using a 1064 nm excitation laser pulses from a Q-switched Nd:YAG 
laser (Continuum Surelite I-10).  A Scientech volume absorbing calorimeter was used 
to measure average laser power.  SHG at 532 nm was visually observed in a darkened 
room from a polycrystalline sample of 3 contained in a glass tube as the intensity of 
the unfocused laser was increased above a beam cross-section averaged intensity of 
4.3 megawatt/cm
2
.  At a given laser intensity above the SHG threshold, the SHG 
intensity from 3 was weak compared to that observed from a commercial ceramic 
frequency doubling laser beam finder (Kentek View-It
?
). 
Crystallographic Studies.  Crystals of Th(SeO
3
)(SeO
4
) (1), 
Th(IO
3
)
2
(SeO
4
)(H
2
O)
3
?H
2
O (2), and Th(CrO
4
)(IO
3
)
2
 (3) were mounted on glass fibers 
and aligned on a Bruker SMART APEX CCD X-ray diffractometer.  Intensity 
measurements were performed using graphite monochromated Mo K? radiation from 
a sealed tube and a monocapillary collimator.  SMART was used for preliminary 
determination of the cell constants and data collection control.  For all compounds, 
135 
the intensities of reflections of a sphere were collected by a combination of three sets 
of exposures (frames).  Each set had a different ? angle for the crystal and each 
exposure covered a range of 0.3? in ?.  A total of 1800 frames were collected with an 
exposure time per frame of 40 s for 1, 60 s for 2, and 30 s for 3.  Longer exposure 
times for 1 and 2 were necessary due to the small size of the crystals.  
For 1-3, determination of integrated intensities and global cell refinement 
were performed with the Bruker SAINT (v 6.02) software package using a narrow-
frame integration algorithm.  A face-indexed absorption correction was initially 
applied using XPREP.
18
  Individual shells of unmerged data were corrected and 
exported in the same format.  These files were subsequently treated with a semi-
empirical absorption correction by SADABS.
19
  The program suite SHELXTL (v 5.1) 
was used for space group determination (XPREP), direct methods structure solution 
(XS), and least-squares refinement (XL).
18
  Some crystallographic details are listed in 
Table 6.1.   
 
RESULTS AND DISCUSSION 
 Syntheses.  The reaction of Th(NO
3
)
4
?xH
2
O with selenic acid in the presence 
of Cs
+
 results in the reduction of Se(VI) to Se(IV) and the subsequent crystallization 
of Th(SeO
3
)
2
 with trace amounts of Th(SeO
3
)(SeO
4
) (1).  This reaction presumably 
proceeds via the oxidation of water.  Yields of 1 were not improved by changing the 
reaction conditions, scale, or stoichiometry.  The preparation of 
Th(IO
3
)
2
(SeO
4
)(H
2
O)
3
?H
2
O (2) is less than straightforward.  In this case, 
Th(NO
3
)
4
?xH
2
O is reacted with H
5
IO
6
, Cr(NO
3
)
3
?9H
2
O, and H
2
SeO
4
 to yield the 
Table 6.1.  Crystallographic Data for Th(SeO
3
)(SeO
4
) (1), 
Th(IO
3
)
2
(SeO
4
)(H
2
O)
3
?H
2
O (2), and Th(CrO
4
)(IO
3
)
2
 (3). 
Formula Th(SeO
3
)(SeO
4
) Th(IO
3
)
2
(SeO
4
)(H
2
O)
3
?
H
2
O 
Th(CrO
4
)(IO
3
)
2
 
  
Formula mass 
(amu) 
501.96 796.86 697.84 
 
Space group P2
1
/c (No. 14) P2
1
/n (No. 14) P2
1
2
1
2
1
 (No. 19) 
a (?) 7.0351(5) 7.4889(9) 7.3672(5) 
b (?) 9.5259(7) 8.002(1) 9.3617(6) 
c (?) 9.0266(7) 20.165(3) 11.9201(7) 
? (?) 90 90 90 
? (?) 103.128(1) 100.142(2) 90 
? (?) 90 90 90
V (?
3
) 589.11(8) 1189.6(3) 822.12(9) 
Z 4 4 4 
T (?C) -80 -80 -80
? (?) 0.71073 0.71073 0.71073 
?
calcd
 (g cm
?3
) 5.660 4.404 5.638 
?(Mo K?) (cm
?1
) 376.48 208.56 269.38 
R(F) for F
o
2
 > 
2?(F
o
2
) 
a
0.0247 0.0471 0.0204 
 
R
w
(F
o
2
) 
b
0.0565 0.1165 0.0423 
 
a
 
()
RF F F F=???
oc o
.  
b
 
() ( )
RF wF F wF
wo
2
o
2
c
2
2
o
4
12
=?
?
?
?
?
?
?
??
?
?
?
?
?
?
. 
136 
137 
desired product.  The periodic acid oxidizes water to yield iodate, which is a 
convenient method for slowly introducing iodate in f-element reactions;
20-22
 the 
Cr(III) is also oxidized to Cr(VI) and remains in solution, and finally the selenic acid 
remains SeO
4
2?
 in this reaction owing to the presence of the strongly oxidizing IO
6
5?
.  
The preparation of Th(CrO
4
)(IO
3
)
2
 (3) is the most direct, involving the oxidation of 
Cr(III) to CrO
4
2?
 by IO
6
5?
 with concomitant reduction to IO
3
1?
.  These then crystallize 
with Th(IV) to yield 3 in near quantitative yield.  Crystals of 3 were not obtained by 
directly reacting chromate and iodate with Th(IV).       
Structure of Th(SeO
3
)(SeO
4
) (1).  This compound adopts a three-
dimensional structure formed from ThO
9
 tricapped trigonal prisms, shown in Figure 
6.1, trigonal pyramidal selenite, SeO
3
2?
, anions containing Se(IV), and tetrahedral 
selenate, SeO
4
2?
, anions containing Se(VI).  The ThO
9
 polyhedra edge-share to form 
one-dimensional chains that extend down the a-axis.  Each selenate anion bridges 
between three such chains.  The selenite anion chelates one thorium center in one 
chain and uses its third oxygen atom to bridge to a second chain.  A view of the 
extended structure is depicted in Figure 6.2.   
Th?O bond distances, which range from 2.354(5) to 2.625(5) ?, are within the 
normal limits, with the two longest Th?O bond distances (2.530(4) and 2.625(5) ?) 
being with the two ?
3
-O atoms of the selenite anions, O(5) and O(6), respectively.  
The selenate bond distances (Se(1)?O) range from 1.625(5) to 1.638(5) ?, which O?
Se(1)?O bond angles being found from 106.9(2) to 113.0(2)?.  Se(2)?O bonds occur 
from 1.677(5) to 1.734(5) ?, with O?Se(2)?O bond angles from 91.1(2) to 103.8(2)?.  
Selected bond distances and angles for 1 can be found in Table 6.2.  Bond valence  
 
 
 
O(2)?
O(5)?
O(7)?
O(5)
O(7)
Se(2)
O(4)?
O(6)
Th(1)
O(6)?
O(3)?
Se(1)
O(4)
O(3)
O(2)
O(1)
 
 
 
 
 
Figure 6.1.  A view of the fundamental building units in Th(SeO
3
)(SeO
4
) (1) showing 
ThO
9
 tricapped trigonal prisms, trigonal pyramidal selenite, SeO
3
2?
, anions containing 
Se(IV), and tetrahedral selenate, SeO
4
2?
, anions containing Se(VI).  50% probability 
ellipsoids are depicted.   
138 
 
 
a
b
c
 
 
 
 
 
Figure 6.2.  A depiction of the extended structure of Th(SeO
3
)(SeO
4
) (1). 
139 
140 
Table 6.2.  Selected Bond Distances (?) and Angles (
o
) for Th(SeO
3
)(SeO
4
). 
Distances (?) 
Th(1)?O(1) 2.404(5) Th(1)?O(7)' 2.354(5) 
Th(1)?O(2)' 2.426(5) Se(1)?O(1) 1.625(5) 
Th(1)?O(3)' 2.458(5) Se(1)?O(2) 1.626(5) 
Th(1)?O(4)' 2.464(5) Se(1)?O(3) 1.638(5) 
Th(1)?O(5) 2.458(5) Se(1)?O(4) 1.638(5) 
Th(1)?O(5)' 2.530(4) Se(2)?O(5) 1.677(5) 
Th(1)?O(6) 2.625(5) Se(2)?O(6) 1.725(4) 
Th(1)?O(6)? 2.429(5) Se(2)?O(7) 1.734(5) 
Angles (?) 
O(1)?Se(1)?O(2) 106.3(2) O(3)?Se(1)?O(4) 112.4(3) 
 
O(1)?Se(1)?O(3) 108.5(3) 
 
O(5)?Se(2)?O(6) 91.1(2) 
 
O(1)?Se(1)?O(4) 113.0(2) 
 
O(5)?Se(2)?O(7) 101.0(2) 
  
O(2)?Se(1)?O(3) 109.5(3) 
 
O(6)?Se(2)?O(7) 103.8(2) 
 
O(2)?Se(1)?O(4) 106.9(2) 
 
 
 
141 
sums calculations were performed on all polyhedral central atoms, resulting in a sum 
of Th(1), 4.14, Se(1), 3.93, and Se(2), 6.10, which are in agreement with the expected 
oxidation states.
23,24
  
Th(IO
3
)
2
(SeO
4
)(H
2
O)
3
?H
2
O (2).  The structure of Th(IO
3
)
2
(SeO
4
)(H
2
O)
3
?H
2
O 
contains two-dimensional sheets extending in the [bc] plain and occluded water 
molecules.  The Th centers are found as isolated ThO
9
 tricapped trigonal prisms 
beingbound by four trigonal-pyramidal iodate anions, two tetrahedral selenate anions, 
and three coordinating water molecules.  All four IO
3
 units coordinate to ThO
9
 on the 
same side in an approximately fourfold pattern through two capping and two trans 
trigonal-prismatic oxygen atoms, as is shown in Figure 6.3.  The two remaining 
trigonal-prismatic oxygen atoms on one side of ThO
9
 are a part of two SeO
4
 units.  
Th(1)?O bond distances range from 2.383(7) ? to 2.611(7) ? with the longer three 
being the bond distances to the coordinating water molecules.  These three 
coordinating water molecules are directed between the layers.  The sheets of 2 are 
porous with gaps on the order of 15.76 x 5.50 ? (Figure 6.4).  The hydrating water 
molecule occupies an optimized position between the sheets and in proximity of the 
pores in the sheets.   
There are two crystallographically unique IO
3
1?
 anions in the structure of 2.  
The iodate anion containing I(1) caps the ThO
9
 unit, and the iodate containing I(2) 
occupies some of the sites forming the trigonal prism.  Each iodate anion has a 
terminal oxygen atom, and these have the shortest bond lengths with I(1)?O(3) being 
1.797(7) ?, and I(2)?O(6) being 1.800(7) ?.  The I(1)?O bond lengths range from 
1.797(7) to 1.819(8) ?, while those of I(2) are very similar with distances from  
 
 
O(9)
O(10)
O(8)
O(6)
I(2)
O(4)
O(5)
O(14)
I(1)
O(3)
O(2)
O(1)
Th(1)
O(5)?
O(13)
O(11)
O(12)
O(2)?
O(7)
O(8)?
Se(1)
 
 
 
 
 
 
Figure 6.3.  An illustration of the ThO
9
, IO
3
1?
, and SeO
4
2?
 units in 
Th(IO
3
)
2
(SeO
4
)(H
2
O)
3
?H
2
O (2).  50% probability ellipsoids are depicted. 
142 
     
 
 
 
 
a
 
b
c
 
 
 
 
 
 
 
 
Figure 6.4.  A view down [111] of the porous sheets in Th(IO
3
)
2
(SeO
4
)(H
2
O)
3
?H
2
O 
(2).polyhedral central atoms.   
143 
144 
Table 6.3.  Selected Bond Distances (?) and Angles (
o
) for 
Th(IO
3
)
2
(SeO
4
)(H
2
O)
3
?H
2
O. 
Distances (?) 
Th(1)?O(1) 2.427(8) I(1)?O(2) 1.819(8) 
Th(1)?O(2)' 2.427(8) I(1)?O(3) 1.797(7) 
Th(1)?O(4) 2.430(8) I(2)?O(4) 1.817(8) 
Th(1)?O(5)' 2.416(8) I(2)?O(5) 1.810(7) 
Th(1)?O(7) 2.383(7) I(2)?O(6) 1.800(7) 
Th(1)?O(8)' 2.385(8) Se(1)?O(7) 1.644(8) 
Th(1)?O(11) 2.463(8) Se(1)?O(8) 1.608(8) 
Th(1)?O(12) 2.611(7) Se(1)?O(9) 1.624(8) 
Th(1)?O(13) 2.496(8) Se(1)?O(10) 1.621(8) 
I(1)?O(1) 1.805(9)   
Angles (?) 
O(1)?I(1)?O(2) 95.7(4)  O(7)?Se(1)?O(8) 106.7(4)  
O(1)?I(1)?O(3) 97.5(4)  O(7)?Se(1)?O(9) 110.5(4)  
O(2)?I(1)?O(3) 98.9(4)  O(7)?Se(1)?O(10) 109.3(4)  
O(4)?I(2)?O(5) 95.4(4)  O(8)?Se(1)?O(9) 107.7(4)  
O(4)?I(2)?O(6) 98.0(4)  O(8)?Se(1)?O(10) 110.9(4)  
O(5)?I(2)?O(6) 96.8(4)  O(9)?Se(1)?O(10) 111.6(4)  
145 
 
1.800(7) to 1.817(8) ?.  The O?I?O bond angles for the two IO
3
 units are also nearly 
identical with ranges of 95.7(4) to 98.9(4)? for I(1) and 95.4(4) to 98.0(4)? for I(2).  
The SeO
4
2?
 anions bridge two ThO
9
 units and also have two terminal oxygen atoms.  
Bond lengths within this unit range from 1.608(8) to 1.644(8) ?, and the bond angles 
from 106.7(4) to 111.6(4)?.  Selected bond distances and bond angles of 2 can be 
found in Table 6.3.  Bond valence sums calculations were performed on all Th(1) 
resulted in a sum of 4.27, Se(1) 6.23, I(1) 5.06, and I(2) 5.03; all results are in 
agreement with stated oxidation states.
23,24
  
Th(CrO
4
)(IO
3
)
2
 (3).  As is 1 and 2 the Th(IV) cations in 3 are found as ThO
9
 
tricapped trigonal prisms.  Each Th center is bound by six IO
3
1?
 anions and three 
CrO
4
2?
 anions (Figure 6.5).  The Th?O distances range from 2.345(5) to 2.670(5) ?, 
and there is no correlation between Th?O bond length and ligand type.  3 crystallizes 
in the chiral space group P2
1
2
1
2
1
, probably owing to the presence of the lone pair of 
electrons on the iodate anions, although this feature is also present in 1 and 2, and 
both of these compounds are centrosymmetric.  Both the I(1)O
3
1?
 and I(2)O
3
1?
 
trigonal pyramidal units bridge between three ThO
9
 units.  The CrO
4
2?
 anions also 
corner-shares with three ThO
9
 units.  The remaining oxygen atom on the CrO
4
2?
 
anions is terminal.  The coordination of the CrO
4
2?
 anions to Th(IV) yields [ThCrO
4
] 
sheets that propagate in the [ab] plane.  The thorium atoms are then further 
coordinated by the iodate anions that link the sheets together to create a three-
dimensional structure as shown in Figure 6.6.     
 
 
 
O(2)
O(3)
O(4)
O(1)
O(4)?
O(6)?
O(10)
O(9)
I(2)
O(7)?
O(8)
O(10)?
O(2)?
O(5)
O(7)
I(1)
O(6)
O(9)?
Th(1)
Cr(1)
 
 
 
 
 
Figure 6.5.  A depiction of the fundamental building units in Th(CrO
4
)(IO
3
)
2
 (3) 
showing a Th center bound by six IO
3
1?
 anions and three CrO
4
2?
 anions.  50% 
probability ellipsoids are depicted. 
146 
 
b 
c 
a 
 
 
 
 
 
Figure 6.6.  An illustration of the extended structure of Th(CrO
4
)(IO
3
)
2
 (3) showing 
[ThCrO
4
] sheets that propagate in the [ab] plane.  These sheets are linked together by 
iodate anions to create a three-dimensional structure. 
147 
148 
The I?O bond lengths range from 1.794(5) to 1.827(5) ?, but due to the 
contortion required of the IO
3
1?
 anions to stabilize and maintain their bonding, all  
I(2)?O bond lengths are longer than those of I(1)?O.  The I(1)O
3
1?
 anion is more 
uniform and has O?I(1)?O bond angles ranging from 94.5(3) to 98.8(3)?.  The 
I(2)O
3
1?
 anion shows more deformity with O?I(2)?O bond angles of 92.8(2), 
100.1(2), and 100.6(2)?.  Cr?O bond lengths are also consistent with literature 
values,
17
 ranging from 1.616(5) to 1.664(5) ?, with the terminal O(3) atom having the 
obvious and expected shortest bond length to Cr(1).  There are no exceptional  
deviations from tetrahedral geometry with its O?Cr?O bond angles of 107.7(3) to 
111.0(3)?.  Selected bond distances and angles for 3 can be found in Table 6.4.  Bond 
valence sums calculations were performed on all polyhedral central atoms.  Th(1) 
resulted in a sum of 4.32, Cr(1) 5.97, I(1) 5.19, and I(2) 4.93; all results being within 
a reasonable error of the stated oxidation state.
23,24
  
 
CONCLUSIONS 
In this report we have demonstrated that the structural chemistry of thorium 
with heavy oxoanions is diverse and rich with previously unknown bonding motifs.  
The high coordination number of Th(IV), nine-coordinate in the compounds reported 
herein, provides a platform for crystallizing solids with both layered and chiral 
networks.  It is noteworthy that one does not solely obtain routine centrosymmetric 
three-dimensional structures as one might have predicted to occur with Th(IV) and 
anions of this type.  A future report will detail the structural chemistry of thorium 
selenites and iodates. 
149 
Table 6.4.  Selected Bond Distances (?) and Angles (
o
) for Th(CrO
4
)(IO
3
)
2
. 
Distances (?) 
Th(1)?O(1) 2.382(5) Cr(1)?O(2) 1.663(5)  
Th(1)?O(2)' 2.670(5) Cr(1)?O(3) 1.616(5)  
Th(1)?O(4)' 2.547(5) Cr(1)?O(4) 1.642(5)  
Th(1)?O(5) 2.345(5) I(1)?O(5) 1.794(5)  
Th(1)?O(6)' 2.402(5) I(1)?O(6) 1.803(5)  
Th(1)?O(7)' 2.408(5) I(1)?O(7) 1.795(5)  
Th(1)?O(8) 2.526(5) I(2)?O(8) 1.809(5)  
Th(1)?O(9)' 2.361(5) I(2)?O(9) 1.812(5)  
Th(1)?O(10)' 2.418(5) I(2)?O(10) 1.827(5)  
Cr(1)?O(1) 1.664(5)    
Angles (?) 
O(5)?I(1)?O(6) 97.5(2) O(1)?Cr(1)?O(2) 108.8(3) 
O(5)?I(1)?O(7) 98.8(3) O(1)?Cr(1)?O(3) 109.9(3) 
O(6)?I(1)?O(7) 94.5(3) O(1)?Cr(1)?O(4) 110.2(3) 
O(8)?I(2)?O(9) 100.6(2) O(2)?Cr(1)?O(3) 111.0(3) 
O(8)?I(2)?O(10) 92.8(2) O(2)?Cr(1)?O(4) 109.1(3) 
O(9)?I(2)?O(10) 100.1(2) O(3)?Cr(1)?O(4) 107.7(3) 
 
150 
Table 6.5.  Atomic Coordinates and Equivalent Isotropic Displacement Parameters 
for Th(SeO
3
)(SeO
4
) (1). 
Atom x y z U
eq
 (?
2
)
a
Th1 0.79089(3) 0.46012(2) 0.13414(3) 0.00888(8) 
Se1 0.87862(9) 0.81878(7) -0.01771(7) 0.01175(15) 
Se2 0.67108(9) 0.40531(7) -0.24986(7) 0.00934(14) 
O1 0.7468(7) 0.6907(5) 0.0234(6) 0.0159(10) 
O2 0.7331(7) 0.9140(5) -0.1466(5) 0.0147(10) 
O3 0.9562(7) 0.9122(5) 0.1347(5) 0.0175(10) 
O4 1.0567(7) 0.7652(5) -0.0933(6) 0.0169(10) 
O5 0.5490(6) 0.4413(5) -0.1088(5) 0.0108(9) 
O6 0.8940(7) 0.4394(5) -0.1268(5) 0.0117(9) 
O7 0.6588(7) 0.2295(5) -0.2555(5) 0.0143(10) 
 
a
 U
eq 
is defined as one-third of the trace of the orthogonalized U
ij
 tensor. 
151 
Table 6.6.  Atomic Coordinates and Equivalent Isotropic Displacement Parameters 
for Th(IO
3
)
2
(SeO
4
)(H
2
O)
3
?H
2
O (2). 
Atom x y z U
eq
 (?
2
)
a
Th1 -0.04274(5) 0.41249(5) 0.129524(18) 0.01278(13) 
I1 0.26156(9) 0.24072(9) 0.00315(4) 0.01602(17) 
I2 0.25381(9) 0.73316(9) 0.05121(3) 0.01485(17) 
Se1 0.35374(14) 0.29853(14) 0.26897(5) 0.0143(2) 
O1 0.0800(12) 0.2338(10) 0.0513(4) 0.0238(18) 
O2 0.1241(10) 0.3231(11) -0.0733(4) 0.0229(18) 
O3 0.2585(11) 0.0235(9) -0.0197(4) 0.0186(16) 
O4 0.2181(11) 0.5359(11) 0.0916(5) 0.0258(19) 
O5 0.2663(11) 0.6429(12) -0.0301(4) 0.0231(18) 
O6 0.4946(10) 0.7506(10) 0.0803(4) 0.0176(16) 
O7 0.2114(10) 0.2810(10) 0.1973(4) 0.0202(17) 
O8 0.4407(11) 0.1166(10) 0.2861(4) 0.0222(18) 
O9 0.5176(11) 0.4257(10) 0.2608(4) 0.0226(18) 
O10 0.2444(10) 0.3603(11) 0.3271(4) 0.0209(17) 
O11 -0.3429(10) 0.4990(11) 0.1511(4) 0.0219(17) 
O12 -0.1101(11) 0.3238(11) 0.2473(4) 0.0205(17) 
O13 0.8439(12) 0.1210(10) 0.1371(4) 0.0240(18) 
O14 0.4447(13) 0.1284(13) 0.1156(5) 0.033(2) 
 
a
 U
eq 
is defined as one-third of the trace of the orthogonalized U
ij
 tensor. 
152 
Table 6.7.  Atomic Coordinates and Equivalent Isotropic Displacement Parameters 
for Th(CrO
4
)(IO
3
)
2
 (3). 
Atom x y z U
eq
 (?
2
)
a
Th1 0.28484(4) 0.47827(3) 0.17429(2) 0.00862(7) 
I1 0.27550(7) 0.76526(5) 0.41736(4) 0.01116(10) 
I2 0.14710(6) 0.75896(5) -0.04405(4) 0.00880(10) 
Cr1 -0.19558(17) 0.55427(12) 0.30372(9) 0.0102(3) 
O3 -0.2473(7) 0.4896(5) 0.4252(4) 0.0182(12) 
O1 -0.0116(7) 0.4730(6) 0.2539(5) 0.0152(11) 
O10 -0.0703(7) 0.8525(5) -0.0499(5) 0.0116(11) 
O5 0.2769(8) 0.6904(6) 0.2788(4) 0.0186(12) 
O9 0.1180(7) 0.6344(5) -0.1590(4) 0.0131(11) 
O8 0.0763(7) 0.6493(5) 0.0730(4) 0.0125(12) 
O7 0.5073(7) 0.8239(6) 0.4238(5) 0.0163(12) 
O6 0.3165(8) 0.6019(6) 0.4934(4) 0.0183(13) 
O2 -0.3649(8) 0.5321(6) 0.2131(4) 0.0187(12) 
O4 -0.1566(7) 0.7257(5) 0.3195(5) 0.0206(12) 
 
a
 U
eq 
is defined as one-third of the trace of the orthogonalized U
ij
 tensor. 
153 
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Skanthakumar, S.; Soderholm, L.; Albrecht-Schmitt, T. E. Inorg. Chem. 2004, 
43, 958.  c) Albrecht-Schmitt, T. E.; Almond, P. M.; Sykora, R. E. Inorg. 
Chem. 2003, 42, 3788. 
7. a) Bean, A. C.; Scott, B. L.; Albrecht-Schmitt, T. E.; Runde, W. J. Solid State 
Chem. 2004, 176, 1346.  b) Bean,
 
A. C.; Scott, B. L.; Runde, W.; Albrecht-
Schmitt, T. E. Inorg. Chem. 2003, 42, 5632.  c) Runde, W.; Bean, A. C.; 
Albrecht-Schmitt, T. E.; Scott, B. L. Chem. Commun. 2003, 4, 478. 
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State Chem. 2004, 177, 4413. 
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11. Nesterenko, V. P.; Glybin, V. P. Czech. J. Phys. 1999, 49, 903.  
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18. Sheldrick, G. M. SHELXTL PC, Version 6.12, An Integrated System for 
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Chem. 2002, 628, 198. 
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Webster, M. Z. Anorg. Allg. Chem. 2004, 630, 479. 
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24. N. E. Brese, M. O?Keeffe, Acta Crystallogr. 1991, B47, 192. 
 
 
156 
Chapter 7 
SYNTHESIS AND CHARACTERIZATION OF THORIUM IN NOVEL THREE-
DIMENSIONAL TOPOLOGIES: Th
2
(CrO
4
)
4
(H
2
O)
2
 AND Th(SeO
3
)
2
. 
 
ABSTRACT 
A modified compositional diagram using the reaction of Th(NO
3
)
4
?xH
2
O, 
Cr(NO
3
)
3
?9H
2
O, and H
2
SeO
4
 has been completed to yield two new thorium compounds, 
Th
2
(CrO
4
)
4
(H
2
O)
2
 (1) and Th(SeO
3
)
2
 (2), which are synthesized under mild hydrothermal 
conditions.  The structure of 1 is three-dimensional, consisting of thorium in both a ThO
8
 
dodecahedron and ThO
9
 tri-capped trigonal prism, simultaneously.  The individual types 
of thorium polyhedra are bridged by chromate to form a two-dimensional sheet.  These 
two unique sheets are then further bridged by chromate to form the three-dimensional 
structure.  In contrast the structure of 2 contains only ThO
8
 dodecahedra which edge-
share to form one-dimensional chains.  These chains are stitched together through 
selenite to form a three-dimensional structure.  Unfilled channels form in 2 between the 
selenite anions.  Crystallographic data: 1, orthorhombic, space group Pbca, a = 
10.9824(6) ?, b = 11.6668(6) ?, c = 22.459(1) ?, Z = 8; 2, monoclinic, space group 
P2
1
/n, a = 7.150(1) ?, b = 10.752(2) ?, c = 7.407(1) ?, ? = 107.526(3)?, Z = 4. 
 
 
157 
INTRODUCTION 
One method of creating compounds, such as ion-exchange, piezo-electric, and 
non-linear optical materials, is to use the natural polarity of oxoanions, such as SeO
3
2-
,
1-5
 
IO
3
2-
,
6-10
 IO
4
3-
,
11,12
 TeO
3
2-
,
4,5,13,14
 and distorted TeO
6
6-
 
15-17,21
 and IO
6
5-
, 
11,18-21
 
incorporated within a structure to aid in the development of either non-centrosymmetric 
compounds or structures with channels or open frameworks, though inclusion of these 
anions is no guarantee of success.  With the exception of the octahedral anions 
mentioned, these moieties contain a stereochemically active lone electron pair, garnering 
both polarity for the anion and an inherent lack of bonding to the electron site.  The 
octahedral anions will exhibit this polarity only when a distortion exists.  The desire to 
produce noncentrosymmetric compounds comes from their ability to exhibit a second-
harmonic generation (SHG) response through frequency doubling of incident light.
8-10,22-
24
   With the incorporation of polar anions in a crystal structure, the likelihood of 
developing a compound with this SHG response is increased. 
Open-framework, or simply channel-structure compounds, can also be made by 
using this same polar anion synthetic approach.
19,20
  In the case of 
K
2
[(UO
2
)
2
(VO)
2
(IO
6
)
2
O]?H
2
O,
20
 channels are developed through the use of distorted 
VO
6
5-
 and IO
6
5-
 octahedra, nonbonding oxoatoms of the uranyl unit, and coordinating 
water molecules, in conjunction with symmetry-imposed mirror planes to cause the 
formation of channels within the structure.  It is reasonable to extend the logic of terminal 
ends leading to open-framework structures by manipulating the lack of bonding of the 
lone electron pair or to use the multiple coordinating ions to form channel structures.  The 
entrapment of alkaline or alkaline earth cations within these channels can then yield 
 
158 
materials suitable for ion-selective exchange, as for the nuclear fission products 
90
Sr and
 
137
Cs. 
The combination of the desire to create these novel compounds with structure-
property relationships corresponds well with our continued progress in the f-block.  The 
sheer number of coordination modes that the actinides exhibit can only augment the 
possibility of creating either of the desired structure-specific results.  The selection of the 
anions also plays a large role in this effect with C
3v
 oxoanions alone able to participate in 
nine distinct binding modes, with that number increasing rapidly as the number of oxygen 
atoms in the anion increase.  To further increase the diversity of coordination capabilities 
in these reactions, tetrahedral anions, which have been previously shown to yield these 
desired effects,
25-27
 are introduced in the systems.  Also, with the substitution of one of 
the coordinating oxygen atom on ThO
9
 by a water molecule, this unit then becomes polar, 
while leaving a terminal position within the structure, and can therefore be tailored to 
result in an extended number of novel structures with either of these structural properties. 
This report is a result of recently acquired compounds stemming from 
experimentation with polar anions, though none of the reported compounds exhibit the 
SHG response desired.   However, thorium selenite does contain a channel, as preferred, 
but this channel is too small to contain a cation, and is therefore unusable as an ion 
exchange material.    
 
 
 
 
 
159 
EXPERIMENTAL 
Syntheses.  Cs
2
CO
3
 (99.99%, Alfa Aesar), Th(NO
3
)
4
?xH
2
O (Alfa Aesar), and 
H
2
SeO
4
 (40% aqueous soln., Alfa Aesar), and Cr(NO
3
)
3
?9H
2
O (Fisher) were used as 
received.  Distilled and Millipore-filtered water with a resistance 18.2 M??cm was used 
in all reactions.  Reactions were run in Parr 4749 autoclaves with 23-mL PTFE liners.  
SEM/EDX analysis was performed using a JEOL 840/Link Isis instrument.  The reported 
preparations are those that gave the highest purity of phases possible. 
Th
2
(CrO
4
)
4
(H
2
O)
2
 (1).  Th(NO
3
)
4
?xH
2
O (0.2727g, 5.48x10
-4
 mol) and 
Cr(NO
3
)
3
?9H
2
O (0.2273g, 5.68x10
-4
 mol) were loaded into a 23 mL PTFE-lined 
autoclave with 1.0 mL H
2
O.  The autoclave was sealed and placed in a box oven 
preheated at 200 ?C to react under autogeneous pressure.  The autoclave was heated for 3 
d and then cooled at a rate of 9 ?C per hour to room temperature.  The brown mother 
liquor was decanted and the products were rinsed with distilled water and methanol and 
allowed to dry.  Dark red, octahedral, Th
2
(CrO
4
)
4
(H
2
O)
2
 crystals were interspersed 
throughout metallic chromium and an unidentifiable yellow powder.  Yield of this 
reaction was extremely low with only a few crystals synthesized in each reaction.  EDX 
analysis results in a Th:Cr ratio of approximately 1:2. 
Th(SeO
3
)
4
 (2).  Cs
2
CO
3
 (0.1713g, 5.26x10
-4
 mol) and Th(NO
3
)
4
?xH
2
O (0.2524g, 
5.26x10
-6
 mol) were loaded into a 23 mL PTFE-lined autoclave with 0.33 mL H
2
O.  0.33 
mL 40% H
2
SeO
4
 (1.28x10
-3
 mol) was then added drop-wise to the reaction mixture.  The 
autoclave was sealed and placed in a box oven preheated at 185 ?C to react under 
autogenous pressure.  The autoclave was heated for 5d and then cooled at a rate of 5 ?C 
per hour to 130 ?C.  The reaction was held for 10 hours and then cooled 5 ?C per hour to 
 
160 
room temperature.  The mother liquor was decanted and the products were rinsed with 
distilled water and methanol and allowed to dry.  The two resulting products, Th(SeO
3
)
2
 
and Th(SeO
3
)(SeO
4
), could not be readily isolated from each other due to intergrowth of 
the crystals.  Th(SeO
3
)
2
 and Th(SeO
3
)(SeO
4
) were visually  distinguishable allowing for 
single crystal diffraction.  EDX analysis confirmed that Th and Se were the only 
detectable elements present in the compound yielding in a 1:2 Th:Se ratio.  Although 
single crystals could be isolated, the intergrowth lead to the inability to measure an 
accurate percent yield, though the majority of the product was Th(SeO
3
)
2
. 
Crystallographic Studies.  Single crystals of Th
2
(CrO
4
)
4
(H
2
O)
2
 (1) and 
Th(SeO
3
)
2
 (2) were selected and mounted on glass fibers using epoxy.  The mounted 
crystal were cooled to -80 ?C during data collection using an Oxford Cryostream and 
optically aligned on a Bruker SMART APEX CCD X-ray diffractometer.  Intensity 
measurements were performed using graphite monochromated Mo-K? radiation from a 
sealed tube with a monocapillary collimator.  SMART was used for preliminary 
determination of the cell constants and data collection control.  For all compounds, the 
intensities of reflections of a sphere were collected by a combination of 3 sets of 
exposures (frames).  Each set had a different ? angle for the crystal and each exposure 
covered a range of 0.3? in ?. A total of 1800 frames were collected with an exposure time 
per frame of 30 s for 1 and 40 s for 2. 
For all compounds, determination of integral intensities and global cell refinement 
were performed with the Bruker SAINT (v 6.02) software package using a narrow-frame 
integration algorithm.  A face-indexed analytical absorption correction was initially 
applied using XPREP.
28
  Individual shells of unmerged data were corrected analytically 
 
161 
and exported in the same format.  These files were subsequently treated with a semi-
empirical absorption correction with SADABS.
29
  The program suite SHELXTL (v 5.1) 
was used for space group determination (XPREP), direct methods structure solution 
(XS), and least-squares refinement (XL).
28
  Hydrogen atom positions for 1 were not 
located from the difference maps and were not included in the final refinement.  The final 
refinements included anisotropic displacement parameters for all non-hydrogen atoms 
and no secondary extinction was apparent (Table 7.1).   
 
RESULTS AND DISCUSSION 
Syntheses.  The syntheses of both 1 and 2 that are reported are not the only 
methods to produce the products, but rather the most effective.  Throughout the 
completion of the modified phase diagram with the reported reactants and H
5
IO
6
, many 
examples of 1 and 2 were discovered as secondary products.  Chromium, with a reduction 
potential of 1.350V at STP
30
 is readily oxidized from Cr(III) to Cr(VI) in the formation of 
1.  Reduction of Se(VI)O
4
2-
, from the starting material, to the Se(IV)O
3
2-
 in 2 has a 
reduction potential of 1.151V
30
 and can oxidize water under mild hydrothermal 
conditions.  Though a slow cooling process can be used to form larger or higher quality 
crystalline products, it is not observed that any other process is necessary than that 
reported.   
 
 
 
 
 
Table 7.1.  Crystallographic data for Th
2
(CrO
4
)
4
(H
2
O)
2
 (1) and Th(SeO
3
)
2
 (2). 
Compound Th
2
(CrO
4
)
4
(H
2
O)
2
Th(SeO
3
)
2
Formula mass 960.08 485.96 
Crystal system Orthorhombic Monoclinic 
Space group Pbca (No. 61) P2
1
/n (No. 14) 
a (?) 10.9824(6) 7.150(1) 
b (?) 11.6668(6) 10.752(2) 
c (?) 22.459(1) 7.407(1)
? (deg.) 
90 90 
? (deg.) 
90 107.526(3)
? (deg.) 
90 90 
V (?
3
) 2877.6(3) 543.0(2)
Z 8 4 
T (?C) 
?80 ?80 
? (?) 
0.71073 0.71073 
?
calcd
 (g cm
?3
) 
4.432 5.945
?(Mo K?, cm
?1
) 
236.04 408.22 
R(F) for F
o
2
 > 2?(F
o
2
) 
a
0.0228 0.0412
R
w
(F
o
2
) 
b
0.0539 0.0990 
a
 
()
RF F F F=???
oc o
.  
b
 
() ( )
RF wF F wF
wo
2
o
2
c
2
2
o
4
12
=?
?
?
?
?
?
?
??
?
?
?
?
?
?
. 
 
 
 
162 
 
163 
 
Structures.  Th
2
(CrO
4
)
4
(H
2
O)
2
 (1).  The structure of Th
2
(CrO
4
)
4
(H
2
O)
2
 (Figures 
7.1 and 7.2) is far more complicated and interesting than the simple thorium chromate 
name or formula suggests.  The two unique thorium oxide polyhedra have distinct 
differences in coordination, although both Th(1) and Th(2) retain the  common Th(IV) 
valence.  This valence has been confirmed through bond valence sum calculations.
31
  
Th(1) exists as a ThO
8
 dodecahedron with one coordinating water molecule within this 
polyhedron.  In this moiety thorium bonds to these oxygen atoms are from 2.294(4) ? to 
the distance to the coordinating water molecule of 2.548(4) ?, which is the expected 
longest bond distance.  All other oxygen atoms are bridging to the four chromium atoms 
that exist within the structure.  However, Th(2) exists as the more often observed ThO
9
 
tri-capped trigonal prism.  The second coordinating water molecule forms one of the 
bases for the trigonal prism.  Once again all remaining oxygen atoms are bridging to 
chromium atoms with no chelating involved.  The Th(2)?O bond distances range from 
2.385(4) ? to 2.530(4) ?.  In this polyhedron the coordinating water does not lay claim to 
the longest bond distance, presumably due to the bonding nature of the chromate 
moieties.  Neither of the thorium oxide polyhedra interacts with each other except 
through bridging chromate. 
All chromate (CrO
4
2-
) moieties exist as tetrahedra with no significant distortion.  
The chromium (VI) valence has also been confirmed by bond valence sum calculations.
31
  
Bond angles for O?Cr?O range from 107.6(2)? to 111.8(2)?.  All of these moieties are 
similar to each other in shape, charge, and ability to coordination to both thorium atoms; 
however, no two have the same coordination environment.  Cr(1)O
4
 is the  
 
 
 
O(10)
O(11)
O(12)
O(15)?
O(4)?
O(14)?
O(6)?
O(10)?
O(13)
O(14)
O(15)
O(16)
O(2)
O(3)
O(4)
O(18)
O(1)
O(7)?
O(6)
O(7)
O(8)
O(5)
O(16)?
O(17) O(8)?
O(3)?
O(9)
Th(1)
Cr(2)
Cr(1)
Cr(4)
Cr(3)
Th(2)
 
 
 
 
 
 
 
 
Figure 7.1.  Thermal ellipsoid plot of the asymmetric unit of Th
2
(CrO
4
)
2
(H
2
O)
2
 at 50% 
probability.  All oxygen atoms depicted are part of either a chromate unit except O(17) 
and O(18) which are water molecules. 
164 
 
 
 
 
 
 
 
a
b
c
 
 
 
 
 
 
 
Figure 7.2.  A view of Th
2
(CrO
4
)
4
(H
2
O)
2
 down the a-axis showing the bridging 
individual layers that are formed.  These layers are joined by the chromate anion. 
165 
 
166 
only unit that bridges equally to Th(1) and Th(2) with O(1) and O(3) bonding to separate 
Th(1) atoms, and the remaining two bridging to separate Th(2) atoms.  This unit?s center 
is shifted toward Th(2) with O(2) and O(4) having the shortest bond distances to 
chromium of 1.638(4) and 1.646(4) ?, respectively.   
Cr(2) and Cr(4) chromate anions are the most similar to each other with three of 
their respective oxygen atoms coordinating to one type of thorium, and the remaining 
oxygen atom bridging to the other.  Cr(2)O
4
 is the most interactive of the chromate 
anions with Th(1), as O(5), O(7), and O(8) bond to three separate Th(1) atoms, and O(6) 
to Th(2).  Cr(4)O
4
 is essentially the opposite with O(13), O(14), and O(15) bonding to 
Th(2), and O(16) to Th(1).  In both cases the oxygen atom that coordinates to the 
opposite type of thorium atom than the others has the shortest bond distances to its 
respective chromium atoms.  The Cr(2)?O(6) bond distance is 1.632(4) ?, while that of 
Cr(4)?O(14) is similar with 1.631(4) ?.   
Cr(3)O
4
 is the only chromate unit that contains a terminal oxygen atom (O(11)).  
This atom has the distinctively shortest bond distance to Cr(3) with a distance of 
1.588(4)? while all other Cr(3)?O bond distances are significantly longer.  O(10) and 
O(12) bond to Th(2) and have identical Cr(3)?O bond distances, 1.655(4) ?.  Cr(3)?O(9) 
is the longest chromium oxygen bond distance in this structure at 1.720(4) ?.  Selected 
bond distances for 1 are shown in Table 7.2. 
Owing to the propensity of bonding in chromate chemistry, each of the unique 
thorium atoms is awarded the opportunity to form layers with the other thorium atoms of 
its type.  Each Th(1)O
8
 is bound to five adjacent Th(1)O
8
 polyhedra through five CrO
4
 
units with one unit (Cr(3)O
4
) being terminal in this regard.  Of these units three (Cr(2)O
4
)  
 
167 
Table 7.2.  Selected Bond Distances (?) for Th
2
(CrO
4
)
4
(H
2
O)
2
. 
Distances (?) 
Th(1)?O(1) 2.400(4) Cr(1)?O(1) 1.647(4) 
Th(1)?O(3)? 2.390(4) Cr(1)?O(2) 1.638(4) 
Th(1)?O(5) 2.427(4) Cr(1)?O(3) 1.664(4) 
Th(1)?O(7)? 2.354(4) Cr(1)?O(4) 1.646(4) 
Th(1)?O(8) 2.416(4) Cr(2)?O(5) 1.644(4) 
Th(1)?O(9) 2.294(4) Cr(2)?O(6) 1.632(4) 
Th(1)?O(16) 2.332(4) Cr(2)?O(7) 1.645(4) 
Th(1)?O(17) 2.548(5) Cr(2)?O(8) 1.652(4) 
Th(2)?O(2) 2.442(4) Cr(3)?O(9) 1.720(4) 
Th(2)?O(4)? 2.398(4) Cr(3)?O(10) 1.655(4) 
Th(2)?O(6)? 2.462(4) Cr(3)?O(11) 1.588(4) 
Th(2)?O(10)? 2.413(4) Cr(3)?O(12) 1.655(4) 
Th(2)?O(12) 2.432(4) Cr(4)?O(13) 1.661(4) 
Th(2)?O(13) 2.438(4) Cr(4)?O(14) 1.631(4) 
Th(2)?O(14) 2.530(4) Cr(4)?O(15) 1.632(4) 
Th(2)?O(15) 2.385(4) Cr(4)?O(16) 1.668(4) 
Th(2)?O(18) 2.450(4)   
 
 
 
bridge to two other Th(1)O
8
 units, while the remaining two Cr(1)O
4
 only bridge to one, 
forming a [Th(CrO)(CrO
2
?
2
)
3
(H
2
O)] sheet along the a/b plain (Figure 7.3).  The 
coordinating O(17) water molecule then fills a small channel that extends down the a-
axis within the layer. 
A second sheet, also along the a/b plain, is comprised of the Th(2)O
9
 polyhedra 
(Figure 4).  Seven CrO
4
 units bind one Th(2)O
9
 moiety to six others:  four bridging to one 
unit and three bridging two units, as well as one seemingly terminal chromate.  This 
[Th(CrO
2
?
2
)
3
(CrO
3
)(H
2
O)] is not exclusive from the previously described sheet including 
Th(1).  These two sheets are joined through utilizing all CrO
4
 units and alternate to form 
the [Th(CrO
3
?
4
)
4
(H
2
O)
2
] structure.  These two layers are jointed through O(6), O(9), 
O(16), and the entirety of Cr(1)O
4
 (Figure 5).   
To maintain the structural stability of Th
2
(CrO
4
)
4
(H
2
O)
2
 the chromate units must 
maintain a close interaction with the thorium atoms forming the individual layers. Due to 
chromate bridging the layers, some of the Th?O bond lengths differ from the expected 
value.  The prime examples in this structure are the bond lengths within Th(2)O
9
.  
Because Cr(2)O
4
 and Cr(4)O
4
 are bound to three thorium atoms in one sheet and one 
opposing thorium atom, the Th(2)?O bond lengths to O(6) and O(14) are extended 
beyond expectation.  This phenomenon is essential to the stability of the structure 
because of the complicated structural pattern.   
 
 
 
 
168 
 
 
 
 
 
a
b
c  
 
 
Figure 7.3.  The  a/b plane shows the [ Th(CrO)(CrO
2
?
2
)
3
(H
2
O)] sheet formed with the 
eight coordinate Th(1)O
8
 polyhedron. 
169 
 
 
 
 
a
b
c
 
 
 
 
Figure 7.4.  Another view of the a/b plain showing the second thorium chromate sheet, 
[ Th(CrO
2
?
2
)
3
(CrO
3
)(H
2
O)], composed of the Th(2)O
9
 polyhedron. 
170 
 
 
 
 
 
 
 
a
b
c
 
 
 
Figure 7.5.  Figure 1 shown with Th(2)O
9
 as a polyhedron and Th(1)O
8
 as the bare 
moiety.  This exemplifies the alternation of the two sheet typologies, which are ultimately 
joined by chromate. 
171 
 
172 
Th(SeO
3
)
2
 (2).  The structure of Th(SeO
3
)
2
 consists of one unique thorium(IV) 
atom bound by eight oxygen atoms forming a distorted dodecahedron (Figure 7.6).  Each 
ThO
8
 polyhedron is connected to two adjacent polyhedra through edge-sharing 
interactions to form the one-dimensional thorium oxide chains that extend infinitely 
down the a-axis.  All oxygen atoms in this structure are either bridging or ?
3
.   
Every oxygen coordinates a singular Se(IV) atom giving the SeO
3
2-
 anions.   
 Se(1)O
3
 chelates to thorium at the point of the thorium polyhedral edge sharing, causing 
these two oxygen atoms to be ?
3
.  The remaining oxygen atom bound to Se(1) bridges to 
a thorium atom of a second chain.   
Se(2) is coordinated only by bridging oxygen, of which two are bound to one 
chain and one to another.  The packing of this structure reveals a pseudo-channel 
extending down the a-axis (Figure 7.7).  The lone pair of electrons of Se(2) is directed 
into the channel in an opposing and alternating fashion, resulting in an alternation of open 
space throughout its length.  These selenite anions stitch each chain to four adjacent 
chains forming the overall three-dimensional structure (Figure 7.8).  The net effect of the 
selenite coordination pattern is an alignment of the stereochemically active lone electron 
pairs of all selenite anions on each chain (Figure 7.9).  Unfortunately the symmetry 
within this structure causes an effective cancellation of this polarity negating any 
potential second-harmonic generation response. 
Th?O bond lengths range from 2.319(9) to 2.576(7) ?, which are within the 
normal range.  The Th??
3
O bond lengths of 2.471(7) ? (O2?) and 2.576(7) ? (O3?) are 
the two longest bond lengths, as expected.  Se(1) bond lengths to these same ?
3
-O atoms 
are again the longest with 1.711(7) and 1.726(7) ? (O3? and O2? respectively).  Se?O  
 
 
 
 
 
 
 
 
 
 
 
 
 
O(2)
O(3)
O(2)?
O(4)?
O(5)
Se(2)
Se(1)
O(3)?
O(4)
O(6)
O(3)?
O(6)?
O(2)?
Th(1)
O(1)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 7.6.  Thermal ellipsoid plot of the asymmetric unit of Th(SeO
3
)
2
 at 50% 
probability.  All oxygen atoms depicted are part of a selenite unit. 
173 
 
 
 
 
 
 
 
c 
b 
a 
 
 
 
 
 
 
 
 
 
 
Figure 7.7.  A view down the a-axis of Th(SeO
3
)
2
 showing an area between four thorium 
oxide chains formed by the opposing polarities of two selenite anions in which the 
electron pairs reside. 
174 
 
 
 
 
 
 
 
 
c 
b 
a 
 
 
 
 
 
 
 
 
 
Figure 7.8.  An expanded view down the a-axis showing the entirety of the Th(SeO
3
)
2
 
structure. 
175 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 7.9.  This view down the c-axis demonstrates the edge sharing that occurs within 
the Th(SeO
3
)
2
 structure.  Both the Se(1)O
3
 and Se(2)O
3
 coordination patterns are also 
shown stitching two chains together, as well as the alignment of the stereochemically 
active lone electron pairs on each anion. 
176 
 
177 
bond lengths are from 1.663(9) to 1.726(7) ?.  O?Se?O bond angles range between 
91.7(4)? to 106.3(4)? with the shortest angle belonging to the chelating O(2)?Se(1)?O(3) 
angle.  Selected bond distances and bond angles are shown in Table 7.3. 
 
CONCLUSION 
Though these specific results have not yielded the desired structure types, other as 
yet unpublished works have revealed the fruitfulness of this endeavor.  Great potential 
has been exhibited in the compounds that were formed with thorium adopting two 
coordination geometries in the formation of two distinctly different sheet typologies in 
Th
2
(CrO
4
)
4
(H
2
O)
2
 and the formation of a gap between the selenite anions in Th(SeO
3
)
2
 
where the electron pairs reside.  The exploitation of these and similar oxoanions has lead 
to great strides in the advance of actinide crystal-phase synthesis as the field begins a 
shift toward structure specificity. 
 
 
 
 
 
 
 
 
 
 
 
178 
Table 7.3.  Selected Bond Distances (?) and Angles (
o
) for Th(SeO
3
)
2
. 
Distances (?) 
Th(1)?O(1) 2.384(7) Th(1)?O(6) 2.331(9) 
Th(1)?O(2) 2.444(7) Se(1)?O(1) 1.665(7) 
Th(1)?O(2)' 2.576(7) Se(1)?O(2) 1.727(7) 
Th(1)?O(3) 2.410(7) Se(1)?O(3) 1.711(7) 
Th(1)?O(3)' 2.471(7) Se(2)?O(4) 1.663(9) 
Th(1)?O(4) 2.319(9) Se(2)?O(5) 1.696(7) 
Th(1)?O(5) 2.332(8) Se(2)?O(6) 1.699(8) 
Angles (?) 
O(1)?Se(1)?O(2) 101.0(4) O(4)? Se(2)?O(5) 101.3(4) 
O(1)?Se(1)?O(3) 101.6(4) O(4)? Se(2)?O(5) 99.4(5) 
O(2)?Se(1)?O(3) 91.7(3) O(5)?Se(2)?O(6) 106.3(4) 
 
 
 
 
 
 
 
 
179 
Table 7.4.  Atomic Coordinates and Equivalent Isotropic Displacement Parameters for 
Th
2
(CrO
4
)
4
(H
2
O)
2
. 
Atom x y z U
eq
 (?
2
)
a
Th1 0.138294(17) 0.713478(16) 0.052600(8) 0.00956(6) 
Th2 -0.302282(17) 0.913318(16) 0.204540(8) 0.00900(6) 
Cr1 -0.21600(8) 0.66059(7) 0.09005(4) 0.00960(16) 
Cr2 0.06510(8) 0.38313(7) 0.08362(4) 0.00973(16) 
Cr3 0.02982(8) 0.95739(7) 0.14273(4) 0.01053(16) 
Cr4 -0.42307(8) 0.64236(7) 0.27894(4) 0.00987(16) 
O1 -0.0724(4) 0.6959(4) 0.07938(19) 0.0190(9) 
O2 -0.2786(4) 0.7526(4) 0.13583(18) 0.0177(8) 
O3 -0.2852(4) 0.6642(4) 0.02415(18) 0.0178(8) 
O4 -0.2223(4) 0.5298(3) 0.11736(18) 0.0172(8) 
O5 0.1130(4) 0.5071(4) 0.0578(2) 0.0226(10) 
O6 -0.0086(4) 0.4016(4) 0.14601(18) 0.0171(8) 
O7 -0.0251(4) 0.3222(4) 0.03445(19) 0.0262(10) 
O8 0.1825(4) 0.2983(4) 0.09675(19) 0.0191(9) 
O9 0.0746(4) 0.8948(3) 0.07693(18) 0.0160(8) 
O10 0.1386(4) 0.9455(4) 0.19332(18) 0.0169(8) 
O11 0.0035(4) 1.0890(3) 0.1301(2) 0.0209(9) 
O12 -0.0949(4) 0.8942(3) 0.16795(18) 0.0146(8) 
O13 -0.4378(3) 0.7625(3) 0.23987(17) 0.0132(8) 
O14 -0.5576(4) 0.5844(3) 0.28525(18) 0.0179(9) 
O15 -0.3275(4) 0.5575(4) 0.24503(19) 0.0190(8) 
O16 -0.3651(4) 0.6743(4) 0.34557(18) 0.0180(8) 
O17 0.3206(5) 0.6025(4) 0.0126(3) 0.0365(13) 
O18 -0.1813(4) 0.7951(3) 0.27252(18) 0.0155(8) 
a
 U
eq 
is defined as one-third of the trace of the orthogonalized U
ij
 tensor. 
 
180 
Table 7.5.  Atomic Coordinates and Equivalent Isotropic Displacement Parameters for 
Th(SeO
3
)
2
. 
Atom x y z U
eq
 (?
2
)
a
Th1 0.23899(5) 0.90076(3) 0.48106(5) 0.01213(17) 
Se1 0.26376(13) 0.71440(9) 0.06371(14) 0.0121(2) 
Se2 0.22765(15) 1.06544(10) 0.93677(15) 0.0143(2) 
O1 0.3529(10) 0.7605(7) 0.2880(11) 0.0164(15) 
O2 0.5974(10) 0.8974(6) 0.5829(12) 0.0159(16) 
O3 -0.0694(11) 0.8965(6) 0.5503(13) 0.0176(16) 
O4 0.1805(14) 0.7050(8) 0.5839(15) 0.035(2) 
O5 0.3156(11) 0.9799(7) 0.7879(12) 0.0206(17) 
O6 0.0124(12) 0.9070(8) 0.1797(13) 0.0263(19) 
 
a
 U
eq 
is defined as one-third of the trace of the orthogonalized U
ij
 tensor. 
 
 
181 
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