Structurally Characterized Iridium(III)-Containing Polytungstate and Catalytic Water Oxidation Activity

The first structurally characterized iridium-substituted polyoxometalate, K(14)[(IrCl(4))KP(2)W(20)O(72)].23H(2)O [1; orthorhombic Pnnm, with a = 18.6546(7) A, b = 19.5192(6) A, c = 14.8670(5) A, V = 5413.4(3) A(3), and Z = 2, final R = 0.0730], is reported. Elemental analysis, X-ray crystallography, and NMR all indicate one Ir atom in each molecule, while IR and electronic absorption spectroscopy, thermal gravimetric analysis, and electrochemistry all indicate its purity in both solid and solution states. Complex 1 is a molecular model of iridium supported on redox-active metal oxides, and aqueous solutions of 1 catalyze oxidation of water to O(2).