SYNTHESIS AND SPECTRAL FEATURES OF Fe(III), Co(II), Ni(II), Cu(II), Zn(II), AND UO2(VI) COMPLEXES OF 3-FORMYL-4-HYDROXY-1,8- NAPHTHYRIDIN-2-ONE (OO) AND ITS ALDOXIME (ON)

Abstract

The bidentate O, O donor ligand, 3-formyl-4-hydroxy-1, 8-naphthyridine-2-one, HL1, and its aldoxime derivative, an O,N donor ligand, HL2, were synthesized and used in chelating metal cations. The structures of the ligands were elucidated by IR and mass spectra. The mass spectra showed the molecular ion peaks at 190 and 205 a.m.u., respectively, corresponding to the formula weights of the ligands. Four types of metal complexes were prepared, [(L)2M(OH2)2].xH2O, [(L)2UO2(MeOH)] and [(L)2Zn]. xH2O [L = L1 or L2, M = Ni(II), Cu(II) and Co(II)], [(L2)2Fe (OH2)Cl].H2O and [L1Fe(OH2)2Cl2].2H2O. It was found that only one type of these metal complexes is obtained regardless whether the metal : ligand ratio was 1 : 1 or 1 : 2 and regardless of the metal salt used, chloride, acetate or perchlorate, except for the Fe(III) complex of HL1 which was formed using only the molar ratio 1 : 1. All complexes exhibted very similar IR features which indicate that the complexes are of similar structures. Electronic spectra and magnetic susceptibility measurements were used to elucidate the structures of the newly prepared metal complexes. The Fe(III), Ni(II), Co(II) and Cu(II) complexes have octahedral geometry formed by the two aldehydic and two phenolate oxygen atoms in the case of complexes of the ligand HL1 and two oxime nitrogen atoms and two phenolate oxygen atoms in the case of complexes of the ligand HL2. In addition, chloride, water or methanol molecules are arranged in axial positions. A pentagonal-bipyramidal geometry for the UO2(VI) complexes and a square-planar geometry for the Zn(II) complexes are suggested.