The metallic thread in a patchwork thesis

A general overview of computational chemistry is presented. Computational studies of macrocyclic rhodium and cobalt compounds were performed at various levels of theory. Computational studies at various levels were performed on gas-phase reactions of niobium and tantalum mono and dications with carbon monoxide and carbon dioxide. An extension to the quasi-atomic minimal basis (QUAMBO) method treatment of virtual orbitals allowing for the inclusion of transition metals is presented. Computations show that in macrocyclic rhodium and cobalt complexes, visible bands for alkyl and nitrosyl complexes involve transitions from M-X bonding orbitals and/or metal d orbitals to M-X antibonding orbitals. In contrast, complexes with X = Cl or NO2 exhibit only d-d bands in the visible, so that homolytic cleavage of the M-X bond requires UV photolysis. Computations indicate that all niobium and tantalum mono and dications react with CO2 to produce metal oxide. While computations indicate that all niobium and tantalum mono and dication reactions with carbon monoxide should form higher order complexes up to M(CO)6x+ where M= Nb, Ta and x=1,2, these higher order complexes were only observed experimentally for dication reactions. A weighted, state-averaged, multi-configurational minimal basis set solution for first and second row transition metals was extracted from existing extended basis set single-configuration methods, and shows promise for extending the QUAMBO method to first and second row transition metals