Structure, solution equilibria and magnetic properties of copper(II) complexes with new sulfurated triazoline derivatives of α-amino acids

Two new sulfurated triazoline ligands have been synthesized by functionalization of glycine and l-alanine at the carboxylate site with retention of chirality in the latter case. The ligands and their copper(II) complexes have been characterized by spectroscopic methods and their structures were determined by X-ray diffraction. In all the complexes the ligands are (N,S) coordinated to copper(II), while the amino groups remain protonated and uncoordinated. The ligands have also been studied in solution and their dissociation constants were determined both by potentiometry and 1H NMR titrations. One copper(II) complex was studied also by magnetic susceptibility measurements, showing an interesting antiferromagnetic behavior at low temperature.