Spectroscopic and computational characterization of Cu^II-OOR (R = H or cumyl) complexes bearing a Me₆-tren ligand

A copper(ii)-hydroperoxo complex, [Cu(Me₆-tren)(OOH)] ⁺ (2), and a copper(ii)-cumylperoxo complex, [Cu(Me ₆-tren)(OOC(CH₃)₂Ph)]⁺ (3), were synthesized by reacting [Cu(Me₆-tren)(CH₃CN)]²⁺ (1) with H₂O₂ and cumyl-OOH, respectively, in the presence of triethylamine. These intermediates, 2 and 3, were successfully characterized by various physicochemical methods such as UV-vis, ESI-MS, resonance Raman and EPR spectroscopies, leading us to propose structures of the Cu(ii)-OOR species with a trigonal-bipyramidal geometry. Density functional theory (DFT) calculations provided geometric and electronic configurations of 2 and 3, showing trigonal bipyramidal copper(ii)-OOR geometries. These copper(ii)-hydroperoxo and -cumylperoxo complexes were inactive in electrophilic and nucleophilic oxidation reactions.