Homogeneous Light-Driven Water Oxidation Catalyzed by a Tetraruthenium Complex with All Inorganic Ligands

A totally homogeneous, molecular, visible-light-driven water oxidation system is reported. The three system components are (i) a water oxidation catalyst, 1 (a RuIV 4O4 cluster stabilized by oxidatively resistant [SiW10O32]8- ligands); (ii) a photosensitizer, [Ru(bpy)3]2+; and (iii) a sacrificial electron acceptor, S2O8 2−. Dioxygen is formed rapidly with an initial turnover frequency of ∼8 × 10−2 s−1 and an estimated quantum yield (defined as the number of O2 molecules formed per two photons absorbed) of ∼9%.