Synthesis, reactivity and catalytic properties of binuclear oxoperoxo complexes of molybdenum (VI) and tungsten (VI) with methylene – or dithio - bridged ligands

Abstract

Oxoperoxo complexes of molybdenum (VI) and tungsten (VI) with the flexibly-bridged hexadentate tetraanionic ligands,&nbsp; LH₄ [LH₄ = Schiff base derived from the condensation of methylene-or-dithio bis (salicylaldehyde) with isonicotinoylhydrazide] have been synthesized and characterized. Reaction of these oxoperoxo complexes with PPh₃ shows the formation of OPPh₃ and conversion ofthe oxoperoxo complexes to the corresponding [MO₂]²⁺ (M =Mo or W) species. Catalytic behaviour of the complexes show that these are effective catalysts for the oxidation of cyclohexanol to cyclohexanone using tert-butylhydroperoxide as an oxidant. While, under similar conditions they fail to catalyse the oxidation of <em>trans</em>-stilbene, cyclohexene or styrene.