Preparation and StructuralCharacterization of Ru^II‐DMSO and Ru^III‐DMSO‐substituted α‐Keggin‐type Phosphotungstates, [PW₁₁O₃₉Ru^IIDMSO]^5– and [PW₁₁O₃₉Ru^IIIDMSO]^4–, and Catalytic Activity for Water Oxidation

Abstract

Abstract Ru II ‐ and Ru III ‐substituted α‐Keggin‐type phosphotungstates with a dimethyl sulfoxide (DMSO) ligand, [PW 11 O 39 Ru II DMSO] 5– ( 1 ) and [PW 11 O 39 Ru III DMSO] 4– ( 2 ), were synthesized. Compound 1 was prepared by reaction of [PW 11 O 39 ] 7– with [Ru II (DMSO) 4 ]Cl 2 in water at 125 °C under hydrothermal conditions and was isolated as a cesium salt. Compound 2 was prepared by reaction of 1 with bromine in water at 60 °C and was isolated as a cesium salt. The compounds were characterized by cyclic voltammetry, elemental analysis, UV/Vis, IR, 31 P NMR, 183 W NMR, 1 H NMR, and XANES (Ru K‐edge and L 3 ‐edge)spectroscopic methods. Single crystal structural analysis of 1 revealed that Ru II is incorporated in the α‐Keggin framework and coordinated by DMSO through a Ru–S bond. Cyclic voltammetry of 1 indicated that the incorporated Ru II ‐DMSO is reversibly oxidizable to the Ru III ‐DMSO derivative 2 . Compound 1 showed catalytic activity for water oxidation in the presence of cerium ammonium nitrate as an oxidant.