Dicopper peroxo complexes: low temperature stopped-flow reaction kinetics of [(BQPA)Cu I] + and [(Me 2-TMPA)Cu I]

In the last 20 years, the reaction of many different Cu I complexes and with dioxygen has been described. There is quite a big variety in their coordination geometry and most of them have been characterized by X-ray crystallography. Beyond structural information, stopped-flow kinetics experiments have provided additional mechanistic insights. In the particular systems [(BQPA)Cu I] + and [(Me 2-TMPA)Cu I] + a new equilibrium between the two species trans-μ-1,2-peroxo and bis-μ-oxo is demonstrated. In the case of [(BQPA)Cu I] + the two species are in an equilibrium, presumably via the transient superoxo species. The reaction of [(Me 2-TMPA)Cu I] + with dioxygen leads to the parallel formation of both species. The kinetically preferred trans-μ-peroxo species is then isomerised to the thermodynamically more stable bis-μ-oxo species.