Dicopper peroxo complexes: low temperature stopped-flow reaction kinetics of [(BQPA)CuI]+ and [(Me2-TMPA)CuI]+.

In the last 20 years, the reaction of many different CuI 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)CuI]+ and [(Me2-TMPA)CuI]+ a new equilibrium between the two species trans-mu-1,2-peroxo and bis-mu-oxo is demonstrated. In the case of [(BQPA)CuI]+ the two species are in an equilibrium, presumably via the transient superoxo species. The reaction of [(Me2-TMPA)CuI]+ with dioxygen leads to the parallel formation of both species. The kinetically preferred trans-mu-peroxo species is then isomerised to the thermodynamically more stable bis-mu-oxo species.