A Crown‐Shaped Ru‐Substituted Arsenotungstate for Selective Oxidation of Sulfides with Hydrogen Peroxide

Abstract

An acetate-bridged Ru-substituted arsenotungstate [H₂ N(CH₃ )₂ ]₁₄ [As₄ W₄₀ O₁₄₀ {Ru₂ (CH₃ COO)}₂ ]⋅22 H₂ O (1) has been synthesized and structurally characterized. Four Ru atoms occupy the respective lacunary S2 sites of the crown-shaped polyanion [As₄ W₄₀ O₁₄₀ ]^28- , and each Ru atom is coordinated by one As atom and five μ₂ -O atoms, comprising four from the S2 site and one from the acetate ligand. To the best of our knowledge, this coordination of the Ru atom, with an Ru-As bond length of 2.377(3)-2.387(3) Å, is unprecedented in polyoxometalate (POM) chemistry. Notably, 1 exhibits high efficiency, excellent selectivity, and good recyclability for the oxidation of sulfides with hydrogen peroxide (H₂ O₂ ). Catalytic oxidation of various sulfides in the presence of 1 gives superior conversion and selectivity for sulfones in acetonitrile, whereas sulfoxides are obtained in methanol.