Copper(II) complexes with aspartate and glutamate.

Aspartic and glutamic acids have been studied as ligands (L) for copper(II) at 25°C and in 1.00 M NaClO4 (as a constant ionic medium), by measuring the electromotive force of galvanic cells containing glass and copper amalgam electrodes in a wide concentration range of the reagents, to elucidate the formation of the protonated species. The experimental data have accounted for the species CuL, CuL2, CuHL, CuHL2, CuH2L2, CuH2L and, for aspartate, CuH4L2. The relative stability constants have been determined and compared with those of glycine and serine. The protonation constants of aspartate have also been determined under the same experimental conditions using an H2 electrode.