Spectroscopic investigations of new Cu(II), Co(II), Ni(II) complexes with γ-l-glutamyl amide as ligand

The [Cu(GTA)2]·4H2O, [Co(GTA)2·(H2O)2]·6H2O and [Ni(GTA)2·(H2O)2]·6H2O) complexes of S(+)-γ-l-glutamyl-(5-ethoxycarbonyl-4-methyl-2-thiazolyl)-amide (HGTA) ligand were synthesized and characterized by elemental, thermal, spectroscopic and magnetic investigations. In all these complexes the γ-l-glutamyl-amide act as a bidentate ligand with coordination involving the carbonyl oxygen and the nitrogen atom of the second amino group. The thermal stability in the 20-700 °C temperature range of the ligand and complexes were discussed. The local structure around the Cu(II) ions is pseudotetrahedral. In the case of Co(II) and Ni(II) complexes two H2O molecules are involved in the metal ion coordination resulting an octahedral stereochemistry.