Copper(ii)-containing tungstotellurates(vi): syntheses, structures and their catalytic performances in selective oxidation of thioethers.

ABSTRACT

We report the syntheses and structures of two new copper(ii)-containing tungstotellurates(vi) Na12[TeVI 2W8O38Cu2(H2O)2]·7H2O (Te2W8Cu2) and Na6[TeVIW6O24Cu(NH2CH2CO2)2]·6H2O (TeW6Cu). The two compounds were synthesized by a simple one-pot method and characterized by single-crystal X-ray diffraction (XRD), powder XRD, FT-IR spectroscopy, elemental analysis, and thermogravimetric analysis in the solid state. Furthermore, their catalytic properties for the selective oxidation of thioethers were also studied systematically. The catalytic experiment results indicate that the tungstotellurate(vi) Te2W8Cu2 is an effective heterogeneous catalyst for the selective oxidation of thioethers to sulfoxides or sulfones by an H2O2 oxidant at room temperature. Under the ambient conditions, Te2W8Cu2 can convert 99% of methyl(phenyl)sulfane to sulfoxides or sulfones with 96% or 99% selectivity, respectively, and the utilization rate of H2O2 is up to 80%. Furthermore, Te2W8Cu2 as a heterogeneous catalyst is stable in the reaction and could be reused at least five cycles with conserved activity.