We have recently demonstrated that the cleavage of an O-O bond in an organic peroxide may be concerted with both electron transfer and proton transfer.1 Kinetic advantage results from the increase of the bond-breaking driving force resulting from the concerted proton transfer. The role of proton-coupled electron transfer (PCET) reactions in the activation of dioxygen by transition metal complexes has also been highlighted.2 In the 4e reduction of O2, the cleavage of the O-O bond has been suggested to occur from metal peroxo and hydroperoxo intermediates. Based on electrochemical studies of in situ generated metal peroxo M-O-O species, mechanistic insights for activating the O-O bond during O2 reduction, including the key role of protons, will be presented and discussed. References
1. C. Costentin, V. Hajj, M. Robert, J-M. Savéant, C. Tard,Proc. Natl. Acad. Sci., U.S.A. 2011, 108, 8559-8564.
2. J. Rosenthal, D. G. Nocera, Acc. Chem. Res. 2007, 40, 543-553.