Dioxygen activation by copper sites: relative stability and reactivity of (mu-eta(2):eta(2)-peroxo)- and bis(mu-oxo)dicopper cores

Investigations of complexes comprising the title cores are summarized with a view toward understanding their interconversion and possible implications in metallobiochemistry. Detailed studies on the solvent and concentration dependence of the equilibrium between (mu-eta(2):eta(2)-peroxo)dicopper(II) (A) and bis(mu-oxo)dicopper(III) (B) cores using mono- and binucleating li gands have elucidated the effects of ligand geometry, solubility, solvent d onor ability and temperature on O-O bond cleavage and formation. These effe cts suggest that similar environmental influences may be significant in met alloenzymes and in particular, raise the possibility of either core being r esponsible for arene hydroxylation by tyrosinase. Recent studies on a synth etic system composed of a [Cu-2(mu-O)(2)](2+) unit ligated to a mixed imine /amine ligand with an appended arene substituent substantiate the notion th at core A or a may be competent in performing arene hydroxylation chemistry . (C) 1999 Elsevier Science S.A.. All rights reserved.