Synthesis, X-ray crystal structures and characterization of copper(II)-2,2′-bipyridyl derivatives of (4-amino)-hippuric acid and of L-proline

In this paper the synthesis and the characterization of two complexes of copper and 2,2'-bipyridyl with amino acids 4-aminohippuric acid and L-proline are reported. The X-ray structure reveals for the first complex, [Cu-2(OH)(OH2)(bipy)(2)(Am-hip)](NO3)(2). 4H(2)O, dinuclear copper(II) cations with nitrate counterions and lattice water molecules. The two metal centres are linked together by a water molecule, a hydroxyl group and the carboxylic moiety of the 4-amino-hippuric acid, the remaining two positions on both metal centres are occupied by bipyridyl molecules. The second compound consists of monomeric [Cu(OH2)(bipy)(L-pro)](+) cations and perchlorate anions. Also in this case copper is five-coordinated in a distorted square pyramidal geometry with the bipyridine nitrogens, one carboxylate oxygen atom and the amino nitrogen of the L-proline ion on the basal plane. (C) 1999 Elsevier Science Ltd. All rights reserved.