(N-acetyl-DL-valinate)copper(II) complexes: effect of amines on the amino acid coordination.

Two compounds, Cu(AcVal)2 and Cu(AcVal)2 · H2O, and their amine adducts, Cu(AcVal)2Bn(AcVal = N-acetyl-DL-valinate ion; n = 1 and B = 1,10-phenanthroline, 2,2′-bipyridyl and piperazine; n = 2 and B = pyridine, 3- and 4-methylpyridine, pyridazine N-methylpiperazine, morpholine and piperidine) were prepared and investigated by means of room temperature infrared, electronic and e.p.r. spectroscopy and low and room temperature magnetic susceptibilities. The results suggest a tetragonal configuration for the Cu(AcVal)2, with CuO4 chromophore, and for the amine adducts, with essentially CuO2N2 chromophore, and a binuclear configuration for the Cu(AcVal)2 · H2O, which shows an exchange integral (-2J) of 351 ± 9 cm-1 and a zero field splitting D of 0.39 cm-1 which are in the range found for the copper acetate monohydrate complex and other similar complexes. The amino acid coordinates by the carboxylate group in all the complexe