Cu-Complexes with Scorpionate Ligands as Models for the Binding Sites of Copper Proteins

The bioinorganic relevance of copper is made evident by its involvement in many crucial biological functions, which include: (1) dioxygen activation (copper oxidases and oxygenases) and transport (hemocyanin), (2) electron transfer (cupredoxins), and (3) nitrite reduction to nitric oxide (copper nitrite reductases). As metalloprotein chemistry is governed by the environment close to the metal center(s), a fertile field of investigation is concerned with the preparation of low molecular weight complexes that mimic the structural or functional features of protein active sites. Trofimenko's scorpionate ligands have been extensively used in biomimetic chemistry as “spectator ligands”, which modulate the electronic and steric properties of the metal ion and of the co-ligands (“actor ligands”), but are not directly involved in the metal-based reactivity. The structural and functional properties of copper complexes with scorpionate ligands used as synthetic analogs for the binding sites of copper proteins are the subject of the present review. The specific Cu-binding sites examined are: the T3 binuclear and the T2 mononuclear sites of dioxygen-binding proteins, the T1 sites of electrontransfer in blue copper proteins, and the T2 site of nitrite reductase.