| 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 astatine⁰́₃solvent 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 Schr©œdinger equation, the Hartree⁸́₂Fock theory, post Hartree⁸́₂Fock 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 CO²́² reduction reaction. The iron porphyrin⁰́₃CO²́² adducts at different Fe oxidation states were explored in detail, and a new reaction mechanism that involves the Fe(I)¹́» species was proposed to explain an unexpected solvent effect that has been recently discovered. Chapter 3 discusses a computational study of the dimetallo-tetrylene [þ̀£æ̀⁹BDIþ̀ʻ¹́łæ̀₆æ̀₆]IrH)²́²(Îơ²́²-E)²́² (E = Pb, Sn) system. The experiments were carried out by Prof. T. Don Tilley⁰́₉s 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 Song⁰́₉s group and Prof. Michael Nippe⁰́₉s 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 H²́² 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)⁸́₂solvent adducts were proposed, and the calculated thermodynamics was able to reproduce the experimentally observed trend. The electronic version of this dissertation is accessible from https://hdl.handle.net/1969.1/197834 |
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