Abstract
Copper proteins mediate both the transport and activation of dioxygen in a number of biological systems. The active sites of these proteins comprise mononuclear, dinuclear, and trinuclear copper centers, with the copper ions displaying a variety of coordination numbers and stereochemistries. Information regarding the mechanism by which these proteins activate dioxygen has been obtained by studies of the reactions of small molecule model copper complexes with dioxygen and its derivatives. Superoxo, peroxo, and bis(μ-oxo) intermediates in these reactions have recently been characterized by X-ray crystallography and this article concentrates on the structures of these intermediates, along with several Cu/ O2 complexes that have been well characterized by spectroscopic methods. The oxygenase-type reactivities of a number of copper complexes on reaction with dioxygen are also discussed.