Bis(benzoyl-beta-alaninate)copper(II) complexes and their amine adducts.

A compound of the type Cu(Bz-β-ala = benzoyl-β-alanine anion) was prepared. Amine adducts of the type Cu(Bz-β-ala)2Bn (n = 1 and B = pipz, 3-pic, 2,2′-bipy, 4,4′ and o-phen; n = 2 and B = Ch3- pipz, pipd, morph, py, 4-pic and en) were obtained by reaction of the amines with Cu(Bz-β-ala)2. Each complex was characterized by elemental analysis, and solution spectroscopy and magnetic moment. For the solid (Cu(Bz-β-ala)2B)N, solid and solution (Cu(Bz-β-ala)2B)·3-pic)2 and solution (Cu(Bz-β-ala)2B)2 (B = py and 4-pic) complexes the physical measurements support a copper acetate monohydrate type coordination. For the Cu(Bz-β-ala)2· o-phen complex in the solid state and in solution the presence of two bands (10500 and 14000 cm−1) in the electronic spectra and their position suggest a six-coordinate, cis-octahedral CuO4N2 chromophore, confirmed by the i.r. spectra which give evidence off bidentate coordination of the amino acid through the carboxylic group. The electronic spectra of all other complexes (one band at 15500-17000 cm−1 are consistent with the presence of square-planar (or strongly tetragonal distorted) coordination with CuO4N2 chromophores. I.r. spectra suggest a monodentate coordination of the amino acids and confirm the amine coordination toward the nitrogen atom. In the Cu(Bz-β-ala)2(en)2 complex a bidentate coordination of the en molecules with the formation of square planar species with CuN4 chromophores, with a weak monodentate interaction of the amino acid in the polar position is proposed. A concentration-dependent colour change with a red shift of the d-d band are also discussed for the solution (Cu(Bz-β-ala)2B)2 (B = py, 4-pic, Ch3-pipz, morph and pipd.