Formally Copper(III)–Alkylperoxo Complexes as Models of Possible Intermediates in Monooxygenase Enzymes

Reaction of [NBu4][LCuIIOH] with excess ROOH (R = cumyl or tBu) yielded [NBu4][LCuIIOOR], the reversible one-electron oxidation of which generated novel species with [CuOOR]2+ cores (formally CuIIIOOR), identified by spectroscopy and theory for the case R = cumyl. This species reacts with weak O–H bonds in TEMPO-H and 4-dimethylaminophenol (NMe2PhOH), the latter yielding LCu(OPhNMe2), which was also prepared independently. With the identification of [CuOOR]2+ complexes, the first precedent for this core in enzymes is provided, with implications for copper monooxygenase mechanisms.