Spectroscopic characterization of a copper(III) trisuperoxide complex bearing both side-on and end-on ligands.

The copper atom reacts with dioxygen in solid argon to form a mononuclear copper dioxygen complex Cu(eta(2)-O(2))(eta(1)-O(2))(2) bearing both side-on and end-on bonded O(2) ligands. The complex is characterized as being a trisuperoxide species with the copper center in its unusual +3 oxidation state. The Cu(III) trisuperoxide complex loses an end-on bonded superoxo ligand in forming the copper bisdioxygen complex under infrared irradiation.