Recent advances in metal-phenoxyl radical chemistry

Abstract

The phenolate ligand is well-known as one of the non-innocent ligands. It is typically shown in biological systems as the ligand of a single copper enzyme galactose oxidase, forming a relatively stable Cu(II)-phenoxyl radical intermediate. On the other hand, some of the one-electron oxidized metal-phenolate complexes are revealed to be high valent metal-phenolate complexes, which are isoelectronic with the metal-phenoxyl radical complexes. Therefore, characterization of the one-electron oxidized metal-phenolate complexes has recently been the subject of intense studies aiming at understanding their oxidation states under the given conditions. This review focuses on metal-phenolate complexes and their one-electron oxidized species and compares the properties of the metal-phenoxyl and high-valent metal-phenolate complexes.