Synthesis, spectroscopic and redox behaviour of some copper(II) and copper(I) biomimetic complexes

Copper complexes with acyclic ligands have been synthesized with a chelate unit of the composition CuN x S y . In the electronic spectra of copper(II) complexes a highly intensive charge-transfer band n S→d x 2 − y 2 (Cu 2+ ) occurs within the range 620–720 nm. Corresponding copper(I) complexes were prepared by electrochemical reduction and characterized by electron spectroscopy. Values of the redox potential ( E 1/2 ) of the CuL 2+/+ pair as well as those of the rate constant of the electrode reaction ( k sh ) were obtained by cyclic voltammetry on a platinum electrode in acetonitrile. The behaviour of the complexes as new models of ‘blue’ copper proteins is discussed.