Superoxo,Peroxo,and Hydroperoxo Complexes Formed from Reactions of Rhodium Porphyrins with Dioxygen:Thermodynamics and Kinetics

摘要

Dioxygen reactions with rhodium tetramesitylporphyrin (TMP)Rh~(II) centre dot (1) and the hydride complex ((TMP)Rh-H (2)) result in formation of superoxo ((TMP)RhO_2 centre dot (3)) (eq 1),mu-peroxo ((TMP)Rh-OO-Rh(TMP) (4)) (eqs 2 and 3),and hydroperoxy ((TMP)Rh-OOH (5)) (eq 4) complexes in benzene at 300 K.The (TMP)Rh system provides an unusual opportunity to evaluate the equilibrium relationship between the superoxo and mu-peroxo complexes (eqs 1-3) and to observe the formation and reactions of the rhodium hydroperoxy species.The central role of these types of dioxygen reactions in hydrocarbon oxidations and the transport and activation of oxygen in biological processes motivates communicating these interim results.