Quantum Chemical Studies on the Catalytic Potential of Anionic Transition Metal Compounds in Methane to Methanol and Carbon Dioxide Carboxylation Reactions
Type of DegreePhD Dissertation
Chemistry and Biochemistry
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Using transition-metal (TM) catalysts in organic chemistry conversion reactions is a well-established practice due to their superior efficiency. They have been particularly useful in both methane to methanol conversion (MTM) and carbon dioxide carboxylation reactions (CDC). But using the anionic forms of these transition metals is relatively recent and has sparked interest in using them as prospective catalysts, especially in light of experimental evidence supporting their stability and producibility. This dissertation describes the catalytic potential of the following transition-metal anions: platinum (Pt‒), palladium (Pd‒), and nickel (Ni‒) for both above-mentioned conversion reactions in addition to iron (Fe‒) in the MTM pathway. The dissertation will emphasize the energy profiles, geometries, turnover frequencies, and electronic structure of catalysts using DFT and post-Hartree-Fock electronic correlation methods. It will also elucidate the mechanism of reactions of the most promising routes through orbital analysis. The introduction briefly describes the computational methods used in this dissertation. The second chapter covers the MTM pathway starting with an introduction to the research history performed. It describes our computational findings for the atomic and ligated TMs catalyzed MTM pathway with emphasis on differentiating between radical and [2+2] routes. The findings from bare TMs are followed by a discussion of the effect on the catalytic efficiency of these TMs using the energetic span model and chemical kinetics analysis. Chapter 3 will outline the catalytic potential of atomic and ligated TMs in CO2 carboxylation reactions with different unsaturated alkanes of various lengths which include ethene, butadiene, and both conjugated and unconjugated octadiene. Conclusions and discussions follow both chapters 2 and 3 with a description of the outlook for future work.