Pyrazine dicarboxylate-bridged arsenotungstate: synthesis, characterization, and catalytic activities in epoxidation of olefins and oxidation of alcohols

Abstract

A praseodymium(III)-containing arsenotungstate K₁₆H₁₅Li₇[Pr₂(H₂O)₃(pzdc)As₃W₂₉O₁₀₃]₂·38H₂O (1) (pzdc = pyrazine-2,3-dicarboxylic acid) was synthesized by a conventional aqueous solution method and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD), and single crystal X-ray diffraction. Structural analysis revealed that compound 1 was constructed by two identical subunits {Pr₂(H₂O)₃(AsW₉O₃₃)₃W₂O₄} bridged together by two pzdc ligands. In addition, compound 1 could act as an efficient catalyst for the epoxidation of olefins and oxidation of alcohols with hydrogen peroxide (H₂O₂) as the oxidant. In particular, the turnover frequency (TOF) in the oxidation of 1-phenylethanol reached up to 10 170 h⁻¹, which is higher than that of previously reported catalysts.