Mesoporous Silicas Modified with Dioxomolybdenum(VI) Complexes: Synthesis and Catalysis

Abstract

The dioxomolybdenum(VI) fragment MoO2X2 has been confined within the ordered mesopores of pure siliceous hexagonal MCM-41 and cubic MCM-48 molecular sieves either by direct grafting (solvent impregnation) with MoO2X2(THF)2 or by using a spacer ligand [L = NC(CH2)2Si(OEt)3]. The materials have been characterised by elemental analysis, powder X-ray diffraction, N2 adsorption, IR spectroscopy, and magic-angle spinning NMR spectroscopy (13C, 29Si). All catalysts, homogeneous and heterogenised, are active in the epoxidation of cyclooctene with tert-butyl hydroperoxide.