Reaction Pathways for Water Oxidation to Molecular Oxygen Mediated by Model Cobalt Oxide Dimer and Cubane Catalysts

Abstract

Hybrid density functional theory calculations have been employed to investigate the water oxidation reaction on model cobalt oxide dimer and cubane complexes. Electronic structure and energetics of these model compounds were thoroughly investigated. The thermodynamically lowest energy pathway on the dimer catalyst proceeds through a nucleophilic attack of a solvent water molecule to Co(V)-O radical moiety. The lowest energy pathway on the cubane catalyst involves a geminal coupling of Co(V)-O radical oxo group with bridging oxo sites. Model systems were found to be very sensitive to the positions of ligands and to the hydrogen-bonding environment leading to different isomer energies.