DIOXYGEN LIGAND TRANSFER FROM PLATINUM TO MOLYBDENUM - ISOLATION OF AHIGHLY REACTIVE MOLYBDENUM(VI) OXOPEROXO DIMER

The reaction of Pt(O-2)(PPh(3))(2) with Mo(O)(2)(mesityl)(2) (mesityl = 2,4,6-Me(3)C(6)H(2)) in pyridine results in the transfer of the diox ygen ligand from platinum to molybdenum giving, in the presence of PPh (4)Cl, a molybdenum peroxo compound 1 in which all the organic moietie s have been lost. This compound epoxidizes tetracyanoethylene at a rat e estimated at 10(4) greater than the known oxodiperoxomolybdenum comp lex 2. Furthermore, 1 exhibits a high selectivity for electron-poor ol efins (TCNE/cyclooctene = 10(3)). Elemental analysis, IR and O-17 NMR indicate that 1 is the tetraphenylphosphonium salt of an oxoperoxomoly bdenum(VI) dimer.