OXIDATION CATALYSIS WITH WELL-CHARACTERIZED VANADYL BIS-BIPYRIDINE COMPLEXES ENCAPSULATED IN NAY ZEOLITE

Vanadyl exchanged faujasite (VO2+-NaY) allows bipyridine complexation, giving a heterogeneous ''ship-in-a-bottle'' catalyst denoted as [VO(b py)(2)](2+)-NaY. The [VO(bpy)(2)](2+) complexes associated with the ze olite are characterised with FT-Raman, FT-IR, XPS, and diffuse reflect ance spectroscopy (DRS), as well as with electron paramagnetic resonan ce (EPR). It is established that the cationic complexes are intrazeoli tic and homogeneously distributed across the zeolite crystals and both the zeolite and the neutral bipyridine ligands stabilise V-IV. The ca talytic oxidation of cyclohexane and cyclohexene with different peroxi des or mono-oxygen atom donors in presence of several solvents is desc ribed. Good epoxide selectivity results from the complexation by bipyr idine thus favoring the heterolytic over the homolytic decomposition p athway of V-peroxo-intermediates.