Synthesis and Spectral Characterization of Metal Complexes Containing Tetra- and Pentadentate Schiff Base Ligands

Two new Shiff base ligands, N,N′-bis[2-hydroxy-3-methoxy-N-(p-methyl phenylene)benzylamine]-2,6-diacetylpyridinimine (H2L1), N,N′-bis[2-hydroxy-3-methoxy-N-(p-methylphenylene)benzylamine]phtaldialdimine (H2L2) and their Cu(II), Co(III), Ni(II), Pd(II), VO(IV) and Zn(II) metal complexes have been prepared and characterized by elemental analyses, FT-IR, electronic spectra, magnetic moments, 1H and 13C NMR spectra, mass spectral and molar conductance data. The mononuclear Co(III) complexes of these ligands have diamagnetic character and octahedral geometry around the metal ion. The ketoimine-enolimine equilibria of the ligands were investigated by electronic spectra and showed that the ligands preferred the ketoimine form in nonpolar solvents. It has been found that the ligands and their complexes are non-electrolytic in nature. Spectral measurements showed that the ligands were coordinated to the metal ion through the azomethine nitrogen and phenolic oxygen atoms. The TG and DTA properties of the compounds have been studied.