Mechanism of Water Oxidation Catalyzed by the μ-Oxo Dimer [(bpy)2(OH2)RuIIIORuIII(OH2)(bpy)2]4+

Ce(IV) oxidation of the ruthenium blue dimer leads to catalytic oxidation of water. Kinetic and spectroscopic studies have revealed evidence for RuVORuV as the active catalyst. Redox cycling occurs between RuIIIORuIII and RuVORuV via a complex sequence of coupled steps involving oxidations by Ce(IV) and second-order cross reactions of the dimer. The oxygen-evolving step is not rate determining in the catalytic cycle.