SYNTHESIS, CHARACTERIZATION AND STABILITY CONSTANT DETERMINATION OF L-PHENYLALANINE TERNARY COMPLEXES OF COBALT(II), NICKEL(II), COPPER(II)WITH N-HETEROCYCLIC AROMATIC BASES AND X-RAY CRYSTAL-STRUCTURE OF UA-1,10-PHENANTHROLINE-L-PHENYLALANINATOCOPPER(II) PERCHLORATE COMPLEX

The ternary L-phenylalanine (L-phe) complexes of Co-II, Ni-II and Cu-I I with heterocyclic bases such as 2,2'-bipyridyl (bipy) or 1,10-phenan throline (phen) were prepared and characterized by conventional method s, IR spectroscopy, pH-metric titrations and, for [Cu(OH2) (phen)(L-ph e)]ClO4, the X-ray structure was carried out. copper is in a square-py ramidal arrangement in which the base is formed by two phenanthroline nitrogens, one carboxylic oxygen and the amino nitrogen of an L-phenyl alaninate ion; the apical site is. occupied by a water molecule. Forma tion constants of Co-II, Ni-II and Cu-II ternary complexes involving 2 ,2'-bipyridyl 1,10-phenanthroline or imidazole and the bidentate L-phe nylalanine were determined. The results indicate that the stability of the ternary complexes containing the same metal ion varies with the n ature of the primary ligand according to the order 1,10-phenanthroline > 2,2'-bipyridyl > imidazole.