Arylalkane photo-oxidation under visible light and O2 catalyzed by molybdenum(VI)dioxo-dibromo (4,4′-dicarboxylato-2,2′-bipyridine) anchored on TiO2
文摘
The molybdenum(VI)dioxo-dibromo compound bearing a carboxylate substituted bipyridyl ligand was anchored covalently onto a TiO2 matrix (DG-25). It was fully characterized by IR(KBr), UV-diffuse reflectance, IR-photoacoustic (FT-IR/PAS) and solid state 13C NMR spectroscopies. Its reactivity as an O-atom transfer agent was tested under visible light irradiation on ethylbenzene and tetraline, stoichiometrically under N2 and catalytically under O2 and then compared with the analogous homogeneous complex bearing a carbomethoxy substituted bipyridine. An important synergic effect was observed, attributed to the photogenerated electron flux, via TiO2, onto the coordination sphere of molybdenum. The anchored system, furthermore, prevented any deactivation of the reactive center, as it is observed in the homogeneous medium, through the formation of a μ-oxo species.
