DFT and Ab Initio Computational Studies of Dinuclear Transition Metal Complexes Bearing Redox Active Ligands
As the sophistication of catalytic inorganic and organometallic chemistry increases, so too do the requirements that new catalysts offer greater control over complex reaction schemes – all for a lower cost. Efficient catalysis requires a relatively smooth potential energy surface for the steps along a reaction pathway; barriers that are too high in energy or intermediates that are too low will impede catalytic turnover. Noble metal catalysts function well for performing transformations on organic substrates in part because the low energies of their d-orbitals are most appropriate for binding and releasing substrates composed of 2p elements. Thus, to perform organometallic catalysis with first-row metals, it may be advantageous to build in methods for decreasing both the energies and the inter-electron repulsion of the 3d orbitals. This should, in effect, make the base metals behave like noble metals, while costing only a small fraction of the price.
This project examines whether this modulation in d-orbital energies of first-row transition metals may be achieved by the combination of metal-metal bonding with redox-active ligands. The steric and electronic control provided by these ligands as well as the decreased inter-electron repulsion resulting from d-d and d-π* interactions will create unique avenues for modulating orbital energies during catalytic reactions. Furthermore, the characterization and reactivity of these compounds may also provide fundamental insight into the mechanisms occurring on the surfaces of bulk metal-catalyzed reactions, since the redox-active ligand will provide a useful model of extended chains of metal atoms. As this project is performed primarily with undergraduate students, the multi-disciplinary research program provides students with broad but accessible experience in the fields of synthetic, physical, and computational inorganic chemistry.