SYNTHESIS, CHARACTERISATION AND CATALYTIC ACTIVITY OF COBALT AND NICKEL METAL COMPLEXES DERIVED FROM N-BENZYLIDENEANILINE SCHIFF BASE LIGAND

Abstract

Transition metal complexes have played a significant role in the enormous growth of the field of catalyst. Schiff bases ligands are able to stabilize many different metal ion(s) in various oxidation states, controlling the performance of metal ion(s) in large varieties of useful catalytic organic transformations [1]. The Cobalt(II) and Nickel(II) metal complexes of N-benzylideneaniline Schiff base ligand were synthesized through treatment of the Schiff base ligand with the corresponding metal halides, normally by heating the Schiff base ligand in the presence of the metal salt under reflux conditions [2]. The resulting metal complexes were found to be crystalline which have been characterized using elemental analysis, electrical conductance, magnetic susceptibility measurements, and spectral techniques like UV-Visible, FT-IR and NMR ( 1 H-NMR and 13 C-NMR) spectrophotometer. The complexes were air-stable, with high melting points and soluble in methanol and some other organic solvents such as n-hexane, diethylether and DMSO. The molar conductance of 1x10 -3 M solutions of the metal complexes in methanol at 27 0 C indicates that the complexes behave as electrolytes. Both Cobalt(II) and nickel(II) complexes of Nbenzylideneaniline ligand shows paramagnetic nature of the complexes. The electronic spectra along with magnetic data suggest square planer geometry for Co(II) and Ni(II) complexes. The FTIR spectra determined the υ(C=N) stretching vibration found in the free ligand at 1627 cm -1 . This band was shifted to the lower frequencies (1603.5 cm -1 ) in the spectra of the metal complexes verify, participation of the azomethine nitrogen in the coordination of the metal ions. Finally, the metal complexes were screened for their catalytic activity via phenol benzoylation reaction and found to be moderately active.