Synergy of Phenylsilsesquioxane and Pyridylpyrazolate Ligands in Hexacopper Cages: Approach to Catalytic Toluene Oxidation

Abstract

Abstract Cage-like Cu6M2 (M = Li or Na) complexes, containing two pairs of ligands, Si5-cyclic silsesquioxanes and pyrazolylpyridines, have been obtained. Two central (Cu···Cu···Cu···M) tetramers are sandwiched by Si ligands, while pyrazolylpyridines behave simultaneously in chelating and bridging manners. Depending on the nature of pyrazolylpyridines and solvating ligands, complexes exhibit different crystal packings. The representative Cu6Na2 complex efficiently promotes the peroxidative oxidation of toluene, exhibiting remarkable selectivity (up to 95%) toward benzoic acid.