Iridium Dioxygen Complexes in the Oxidation of Substrates: Kinetics, Mechanism, and Steric and Electronic Effects in the Oxidation of CO, CO₂, PPh₃, and SO₂ by RIr(O₂)(CO)L₂ (R = Me, Ph, Np; L = PPh₃, P(p-tolyl)₃, PPh₂Me, P(p-C₆H₄OMe)₃)

The preparation, characterization, and oxygen-transfer reactivity of the iridium dioxygen complexes RIr(O₂)(CO)L₂ (R = Me, Ph, Np; L = PPh₃, P(p-tolyl)₃, PPh₂Me, PMe₂Ph, and P(p-C₆H₄OMe)₃) are reported. These complexes oxidize carbon monoxide to carbonate, sulfur dioxide to sulfate, carbon dioxide to peroxycarbonate, and triphenylphosphine to triphenylphosphine oxide but are relatively inert to other possible substrates. The kinetics of the oxidations of CO and CO₂are reported and indicate a mechanism of reversible conversion of the dioxygen from bidentate to monodentate followed by reaction with free substrate in solution. The phosphine ligand dependence on the rate of CO oxidation indicates that more electron density slightly increases the rate of oxygen transfer and that steric interactions impede the rate.