Published Paper Details:

A series of new structurally novel unsymmetrical tetra dentate Schiff base metal (II) complex of nickel (II) was prepared by refluxing together the relevant unsymmetrical Schiff bases with the corresponding nickel (II) acetate in methanolic medium. The 1H NMR spectral data of the free ligand were recorded in CDCl3 against tetra methylsilane (TMS) as internal reference. The appearance of two different peaks for each of the azomethine protons and phenolic protons confirm the unsymmetrical nature of the Schiff bases in the series. The absorption bands due to amino group disappeared in the IR spectra of all the four ligands [H2L1-4] which showed that the amino group in the diaminopyridine condensed with the aldehydes. The bands appearing at 1600-1640 cm-1 due to azomethine group of the ligands is shifted to lower frequency at 1570-1600cm-1 in the nickel (II) complexes indicating the participation of the azomethine nitrogen in coordination with the metal ion. The infrared spectra of both the ligands and complexes have no bands between 3100 and 4000 cm-1 indicating the absence of uncoordinated N-H and uncoordinated -OH groups. Due to unsymmetrical nature of the ligands and the complexes two bands were observed for each of the following modes. ?C=N, ?M-N and ?M-O .