Catalytic ring-opening addition of thiols to epoxides in the gas-phase over molecular rhenium sulfide cluster complexes [Re6S8X6] (X = Cl, OH, H2O) with retention of their octahedral metal frameworks

•Aliphatic and aromatic thiols added to epoxides to yield β-hydroxy sulfides.•The selective gas-phase catalysis proceeded at 175–250 °C.•Molecular rhenium sulfide clusters catalyzed the reaction.•The activation mechanism of rhenium cluster was investigated.•Brønsted acid sites developed on the rhenium cluster.

A series of molecular rhenium sulfide clusters K4[Re6S8Cl6] (1), K4[Re6S8(OH)6], and [Re6S8(H2O)6]SO4 supported on silica gel catalyze ring-opening addition of thiols to epoxides to yield β-hydroxy sulfides in a stream of hydrogen at temperatures ranging from 175 to 250 °C. The thermal activation mechanisms of 1 is studied. Powder X-ray diffraction analyses and Raman spectrometry reveal the retention of integrity of the octahedral cluster framework up to 500 °C. Thermogravimetry and elemental analyses of the silica gel-supported 1 show the loss of chlorido ligands, and evolution of hydrogen chloride is observed on activation. No coordinatively unsaturated metal site is observed by CO titration. Titration of the activated cluster shows the appearance of weak Brønsted acid sites with H0 ≈ 1.8. The catalytically active site of the silica gel-supported 1 is a hydroxo ligand that is formed by reaction with silanol groups.

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