MECHANISTIC STUDIES OF ORGANOMETALLIC COMPOUNDS USING DENSITY FUNCTIONAL THEORY

Abstract

This work explores the complex details of transition states, reaction intermediates,and energy landscapes, offering insights into the underlying processes. The first chapter explores a palladium catalyst for C-H functionalization where utilization of differing ligands (pyrimidine versus MeS(CH2)3SO-) enables selection of steric versus contra-steric reactivity. This reactivity was observed in a change in rate-determining step from C-H cleavage to migratory insertion. These reaction pathways were mapped using DFT ground states and transition states in comparison to experimental kinetic isotope effect results. The second chapter discovers an electrocatalyst ((Cr2O3)3Ga2O3) for the production of 1-butanol. Density functional theory was used to discover the key Ni-bound intermediate based on data matched to Inductively Coupled Plasma-Optical Emission spectroscopy. This Ni-bound intermediate is a pivotal step in the production of 1-butanol based on our proposed mechanism. The third and fourth chapters examine manganese catalysts. The third chapter is centered on a di-manganese bipyridine CN-bridge catalyst series. These DFT series show that ligand additions and substitutions on the bipyridine rings allows for variability in the lowest unoccupied molecular orbital. Exploration of the singly reduced state of the series indicated steric changes towards a sterically unfavorable eclipsed conformation in the single electron reduced state. The fourth chapter explores similar manganese bipyridine catalysts by extending the p-system. Extensions of the p-system show increases in the energy of the lowest unoccupied molecular orbital and metal-ligand charge transfer band. Additional DFT studies showed a change in spin orbital density with expansion of the p-system and serial reductions. This work centers on the power of DFT and the power of computations to enlighten or 5 confirm unclear aspects of mechanism. By leveraging the predictive capabilities of DFT, one can gain a deeper understanding of the catalytic behavior of organometallic complexes, paving the way for the design and optimization of catalysts with enhanced efficiency and selectivity.