Conversion of Molecular Oxygen into a Hydroperoxo Species by Ring-Opening Protonation of a Cyclicη2-Peroxo Intermediate: Characterization of theη2-Peroxo and Hydroperoxo Complexes

A transition metal–hydroperoxo species is formed by the oxygenation of a low-valent rhodium precursor followed by a protonation of the resulting η2-O2 ligand; the latter process is assisted by an intramolecular hydrogen-bonding interaction (see scheme). This process is the first structural evidence for an effective method for the activation of molecular oxygen as postulated for the cytochrome P-450 system.