Glutamate and aspartate complexes of copper(II): equilibrium and E.P.R. measurements

Complexes [CuHL]+ containing protonated ligand have been characterized for the ligands L-glutamate and L-aspartate: logK3(M+H+L↔MHL) = 12.62±0.05 and 12.70±0.03 respectively, at 25°C, I 0.10 M KNO3. Equilibrium constants have been redetermined for the complexes [CuL] and [CuL2]2-. Visible absorption and e.p.r. parameters are reported for the complexes; these data establish that the complexes [CuHL]+ have the α-amino carboxylate group coordinated to copper(II).