Spectroscopic studies on some sulphur-containing amino acid complexes of cobalt, nickel and copper

Abstract

The synthesis of three potentially sexadentate optically active sulphur-containing amino acids, 2,9- diamino-4,7-dithiadecanedioic acid [(R,R)-ebc], 2,ll-diamino-5,8-dithiadodecanedioic acid [(S,S)- ebhc] and 2,7-di(3'-thiabuty1)-3,6-diazaoctanedioic acid [(S,S)-ebm] are described. Some metal complexes of the acids with cobalt, nickel and copper are characterized by spectroscopic measurements. The complex�� (-)589[Co{(S,S)-ebm}] ClO4 is formed stereospecifically and an X-ray structural analysis shows it to have the Δ-trans(O) configuration. The c.d. spectrum shows the presence of three bands due to the splitting of the T1g energy level by the effective C2 symmetry of the ligand field. Some polymeric cobalt(11) and nickel(11) complexes are also described. Spectral measurements indicate an octahedral coordination of the ligands involved. Several copper(11) complexes are also described.