POLYOXOANION-SUPPORTED, ATOMICALLY DISPERSED TRANSITION-METALS - THE CATALYTIC-OXIDATION OF CYCLOHEXENE WITH DIOXYGEN BY THE CATALYST PRECURSORS [(N-C4H9)4N]5NA3[(1,5-COD)IR.P2W15NB3O62], [(N-C4H9)4N]5NA3[(1,5-COD)RH.P2W15NB3O62], AND [(N-C4H9)4N]4.5NA2.5[(C6H6)RU.P2W15NB3O62]

Title full: Polyoxoanion-supported, atomically dispersed transition metals: The catalytic oxidation of cyclohexene with dioxygen by the catalyst precursors [(n-C4H9)4N]5Na3[ (1,5-COD)Ir·P2W15Nb3O62 ], [(n-C4H9)4N]5Na3[ (1,5-COD)Rh·P2W15Nb3O62 ], and [(n-C4H9)4N]4.5Na2.5 [(C6H6)Ru·P2W 15Nb3O62]. [(n-C4H9)4N]5Na3[ (1,5-COD)Ir·P2W15Nb3O62 ], 1, [(n-C4H9)4N]5Na3[ (1,5-COD)Rh·P2W15Nb3O62 ], and [(n-C4H9)4N]4.5Na2.5 [(C6H6)Ru·P2 W15Nb3O62] have been shown to catalyze the oxygenation of cyclohexene with molecular oxygen. The polyoxoanion-supported iridium(I) complex, 1, shows the highest activity of this group with a turnover frequency of 2.9 h-1 at 38°C in CH2Cl2 (540 total turnovers), which is 100-fold greater than its parent iridium compound, [(1,5-COD)IrCl]2. Additional experiments using H2/O2 mixtures and H2O2 are also discussed. The apparent rate law for the oxidation of cyclohexene by O2 by 1 is -d[cyclohexene]/dt = k2 obsd · [1]1[cyclohexene]1P(O2)1→0 . These compounds constitute the first examples of oxygenation catalysis using molecular oxygen and a polyoxoanion-supported transition-metal precatalyst. © 1991.