COMPARISON OF THE RELATIVE EFFICIENCY OF PEROXOMOLYBDENUM COMPLEXES AS OXIDANTS OF THE ALCOHOLIC FUNCTION

The oxidative ability toward the alcoholic function of a series of peroxomolybdenum complexes has been evaluated by measuring the oxidation rates and the nature of the products in the oxidation of two model alcohols, i.e. cyclohexanol and 1-octanol. Included in the series are two complexes, i.e. [MoO(O2)2(C6H5COO)]- (Bu)4N+ and [2MoO(O2)2(MeOH)2(MoO(O2)O)2 (MeO)2]2- [(Bu)4N+]2 which have been synthesized for the first time and characterized by X-ray analysis. On the basis of the reactivity data and of the structural features of the oxidants, the requisites that allow the peroxomolybdenum complexes to act as effective and selective oxidants of the alcoholic function have been selected. The necessary requisite appears to be the anionic nature of the oxidant. An important role is also played by the availability of a free or releasable coordination site on the complexes. Such a site should be the second apical position of the species which in all cases displays pentagonal pyramid or bipyramid geometry. Some preliminary mechanistic considerations based on the results obtained are presented envisaging the coordination of the substrate as an alkoxo derivative prior to the oxidation step.