Synthesis and characterization of cobalt(II) complexes with bidentate Schiff base ligand

Abstract

The coordination complexes of Co(II) have been prepared from bidentate Schiff base. The Schiff base ligand was synthesized by the condensation of 4- hydroxy-3-methoxybenzaldehyde and 2-aminobenzhydroxamic acid in an alcoholic medium at room temperature. The ligand and cobalt (II) complexes were characterized by elemental analysis, molar conductance, electronic spectra, IR spectra, NMR spectra, electrical conductivity and magnetic susceptibility. The cobalt (II) complexes are colored and stable in air. In the metal complexes, the metal -ligand ratio was found to be 1:2. A sharp band at 1630 cm-1 is characteristics of the azomethine group present in the Schiff base ligand. This band was shifted to lower frequency (1605 – 1620 cm-1) in all the cobalt complexes, indicating the coordination of the azomethine nitrogen to the metal ion in complexes. The ν(N-OH) stretching vibration of the ligand obtained at 1080 cm-1 was raised up by 10-40 cm-1 in the complexes suggesting the deportation of (N-OH) hydrogen and coordination of hydroxy imino nitrogen atom in the bond formation with the Co(II) ions. The molar conductivity data of the complexes in DMF solution indicates that they are of non-electrolytic nature. On the basis of elemental analysis, magnetic susceptibility and electronic spectral data, geometry of complexes was proposed to be octahedral.