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 aqua-1,10-phenanthroline-L-phenylalaninatocopper(II) perchlorate complex

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