Chemistry of Gold(III) Complexes with Nitrogen and Oxygen Ligands

The chemistry of gold has advanced considerably during the past decade. A large variety of gold compounds have found applications in various fields including catalysis [1], medicinal chemistry [2], photophysics and photochemistry [3] just to mention some of the most recently emerging areas.Arenewed interest in these fields has prompted many researchers to synthesize new gold complexes with specific properties. In particular, gold(III) complexes with nitrogen and oxygen donor ligands occupy a predominant place. The versatility of nitrogen ligands [4], particularly heterocycles, has been exploited to give rise, inter alia, to a flourishing class of cycloaurated derivatives [5], most of which display promising antitumor activity. Polydentate nitrogen ligands and their derivatives have also been prepared for pharmacological and photophysical applications. Furthermore, several known complexes have been re-evaluated in the light of their possible catalytic and/or pharmacological activity and, in some cases, modifications (e.g., substitution of the ancillary ligands) have been made to vary their properties. In spite of the low affinity for binding to oxygen, gold(III) alkoxo, hydroxo and even oxo complexes have been obtained [6, 7]. These are valuable models for Au-O(H) species which are likely to be involved in oxidation reactions catalyzed by metal-oxidesupported gold [8]. All these complexes have displayed interesting chemical reactivity and, in some cases, remarkable catalytic activity.