Water oxidation at a tetraruthenate core stabilized by polyoxometalate ligands: Experimental and computational evidence to trace the competent intermediates

Abstract

(Chemical Equation Presented) Converging UV-vis, EPR, rRaman, and DFT calculations highlight the evolution of [Ru4(H2O) 4(μ-O)4(μ-OH)2(γ-SiW 10O36)2]10-, 1, to high-valent intermediates. In analogy with the natural enzyme, five different oxidation states, generated from 1, have been found to power the catalytic cycle for water oxidation. A high electrophilic tetraruthenium(V)-hydroxo species is envisaged as the competent intermediate, undergoing nucleophilic attack by an external water molecule as a key step in the formation of a new O-O bond under catalytic conditions. © 2009 American Chemical Society.