NATURAL GLYCINE UNIDENTATE ON COPPER(II) - A NOVEL MODE OF BONDING

The compound of composition copper(II)-glycinate-picric acid-water (1/ 2/2/6) has been prepared and its crystal structure determined. It cont ains a centrosymmetric copper(II) ion, co-ordinated in a distorted oct ahedron by two water molecules in trans positions. two unidentate glyc ine moieties, linked to the metal in a trans arrangement via single ca rboxylate oxygens, and two more distant water molecules. The unidentat e glycine species, probably zwitterions, represent an unexpected non-c helated form of the ligand. New similar compounds of (S)-alanine and ( S)-lysine have also been prepared. The nature of the complexed ions in solution ('speciation') is considered.