REACTION ASPECTS OF A MU-PEROXO BINUCLEAR COPPER(II) COMPLEX

The reactivity of a μ-peroxo binuclear copper(II) complex [Cu(HB(3,5-Me2pz)3)]2(O2) (1) toward a variety of substrates is described. PPh3 and CO are not oxidized by 1; they generate mononuclear copper(I) complexes Cu(L)(HB(3,5-Me2pz)3) (L = CO, PPh3) via displacement reactions. Cyclohexene is oxidized to oxygenated products such as 2-cyclohexen-1-ol only under aerobic conditions, and labeling experiments established that the oxygen atoms incorporated into the products come from the exogeneous dioxygen, not from the peroxide ion in the μ-peroxo complex. Phenols and a catechol are oxidatively coupled under anaerobic conditions, while under a dioxygen atmosphere, both oxidatively coupling and oxygenation to give benzoquinones are observed. On the basis of kinetic results, a mechanism is proposed for the oxygenation reactions in which homolytic cleavage of the O-O bond in the μ-peroxo complex is followed by free radical chain reactions with dioxygen. © 1990, American Chemical Society. All rights reserved.