Schiff base complexes of methyltrioxorhenium (VII): Synthesis and catalytic application

•Schiff base–MTO adducts are prepared and characterized.•The complexes catalyze epoxidation in the UHP-ionic liquid system.•The catalysts are highly selective for olefin epoxidation.•This system provides an environmentally benign way for olefin epoxidation.

Schiff bases coordinate smoothly with methyltrioxorhenium (MTO) to yield the corresponding MTO–Schiff base adducts, which were characterized by IR, NMR and elemental analysis. The X-ray structure of one of the complexes was exemplary determined. The compounds were used as catalysts for cyclooctene epoxidation in ionic liquids with UHP (urea hydrogen peroxide adduct) as oxidant at room temperature. The results show that (N-salicylidene)aniline derived Schiff base complexes of MTO displayed higher catalytic activity and selectivity than di-nitrogen Schiff base complexes of MTO. No diol byproduct formation is observed.

Graphical abstractEight base adducts of MTO were prepared, characterized and applied for the epoxidation of olefins with urea hydrogen peroxides adducts as oxidant in ionic liquid at room temperature.Figure optionsDownload full-size imageDownload as PowerPoint slide