Quantum Chemical Characterization of Water Oxidation Catalysts

This chapter reviews computational studies on the water oxidation mechanisms of mononuclear and dinuclear ruthenium catalysts, the cobalt hangman corrole catalyst, and the iron-TAML catalysts. Diagonal steps are protoncoupled electron transfers (PCET) reactions. The relevance of a first solvation-shell water molecule was considered through extensive conformational searches as a hydrogen-bonding network could stabilize the conjugate base and acid forms of the-CO2H moiety. The chapter reports only the free energy of the most stable conformer in each case. It presents the results of a density functional theory (DFT) study together with multireference second-order perturbation theory to elucidate the mechanism of water oxidation in the iron(III)-centered tetraamido macrocyclic ligand (FeIII-TAML) catalyst.