Characterization and Reactivity of a Tetrahedral Copper(II) Alkylperoxido Complex.

A tetrahedral Cu alkylperoxido complex [Cu (TMG tach)(OOCm)] (1 ) (TMG tach={2,2',2''-[(1s,3s,5s)-cyclohexane-1,3,5-triyl]tris-(1,1,3,3-tetramethyl guanidine)}, OOCm=cumyl peroxide) is prepared and characterized by UV/Vis, cold-spray ionization mass spectroscopy (CSI-MS), resonance Raman, and EPR spectroscopic methods. Product analysis of the self-decomposition reaction of 1 in acetonitrile (MeCN) indicates that the reaction involves O-O bond homolytic cleavage of the peroxide moiety with concomitant C-H bond activation of the solvent molecule. When an external substrate such as 1,4-cyclohexadiene (CHD) is added, the O-O bond homolysis leads to C-H activation of the substrate. Furthermore, the reaction of 1 with 2,6-di-tert-butylphenol derivatives produces the corresponding phenoxyl radical species (ArO ) together with a Cu complex through a concerted proton-electron transfer (CPET) mechanism. Details of the reaction mechanisms are explored by DFT calculations.