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Density Functional Theory Calculations of Iron Porphyrin, Dimetallo-Tetrylene and Astatine Systems: Revealing the Electronic Structure and the Reaction Mechanism
Abstract
Density functional theory (DFT) is a quantum chemistry method that studies the electronic structure of many-electron systems such as molecules and condensed phases. Due to its favorable scaling factor with system size, DFT has gained wide applications in chemistry, physics, and material science. This dissertation is focused on the application of DFT calculations in inorganic molecular systems, including iron porphyrin, dimetallo-tetrylene, and astatine–solvent adducts, to shed light on their electronic structure and the reaction mechanism.
This dissertation is arranged into five chapters. Chapter 1 introduces the fundamental concepts of quantum chemistry calculations, including the Schrödinger equation, the Hartree−Fock theory, post Hartree−Fock methods, and DFT. Some practical aspects of DFT applications, such as the choice of density functionals and basis sets, the solvation, dispersion, and relativistic corrections, are also discussed.
Chapter 2 discusses a computational study of the iron porphyrin system for electrocatalytic CO₂ reduction reaction. The iron porphyrin–CO₂ adducts at different Fe oxidation states were explored in detail, and a new reaction mechanism that involves the Fe(I)⁻ species was proposed to explain an unexpected solvent effect that has been recently discovered.
Chapter 3 discusses a computational study of the dimetallo-tetrylene [ᴹᵉBDIᴰⁱᵖᵖ]IrH)₂(μ₂-E)₂ (E = Pb, Sn) system. The experiments were carried out by Prof. T. Don Tilley’s group. The molecular geometries, spin states, aromaticity, etc., were calculated. The fact that E = Ge did not yield the same type of dimer was explained by the calculated reaction thermodynamics.
Chapter 4 discusses a collaboration project with Prof. Dong Hee Song’s group and Prof. Michael Nippe’s group on the formate conversion with Mn-doped quantum dots. Using DFT calculations, the mechanism of yielding the main product CO and the side product H₂ was proposed. The microscopic step that the hot electrons played its role was also revealed.
Chapter 5 discusses a collaboration project with Cyclotron Institute on the astatine extraction from aqueous solutions. Use of methyl anthranilate was found to have a much higher partition coefficient in the organic phase. The proposed structure of the At(III)−solvent adducts were proposed, and the calculated thermodynamics was able to reproduce the experimentally observed trend.
Citation
Zhang, Bowen (2022). Density Functional Theory Calculations of Iron Porphyrin, Dimetallo-Tetrylene and Astatine Systems: Revealing the Electronic Structure and the Reaction Mechanism. Doctoral dissertation, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /197834.