Abstract: | Abstract Copper is classed as a transition metal both from its physico-chemical properties and its biochemical behavior. This review includes thirty formally copper(III) compounds where crystal structure has been determined. Coordination number four dominates with mostly a square-planar arrangement about the copper(III) atom. Sulfur donor ligands by far prevail. In general the Cu-L bond distance elongated with a decreased oxidation state of copper in the sequence: Cu(III)-L > Cu(II)-L > Cu(I)-L. Examples of distortion isomerism exist. |