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

Reaction of [NBu₄][LCu^IIOH] with excess ROOH (R = cumyl or tBu) yielded [NBu₄][LCu^IIOOR], the reversible one-electron oxidation of which generated novel species with [CuOOR]²⁺ cores (formally Cu^IIIOOR), 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(OPh^NMe2), 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.