Synthesis, characterization and electrochemical behavior of some Ni(II), Cu(II), Co(II) and Cd(II) complexes of ONS type tridentate Schiff base ligand

Tridentate Schiff base (H2L) ligand was synthesized via condensation of o-hydroxybenzaldehyde and 2-aminothiophenol. The metal complexes were prepared from reaction of the ligand with corresponding metal salts presence of substituted pyridine in two different solvents (MeOH or MeCN). The ligand and metal complexes were then characterized by using FTIR, TGA, 1H NMR and 13C NMR spectroscopies. The FTIR spectra showed that H2L was coordinated to the metal ions in tridentate manner with ONS donor sites of the azomethine N, deprotonated phenolic-OH and phenolic-SH. Furthermore, substituted pyridine was coordinated to the central metal atoms. The thermal behavior of the complexes was investigated by using TGA method and dissociations indicated that substituted pyridine and ligand were leaved from coordination. This coordination of the metal complexes was correlated by 1H NMR and 13C NMR. Finally, electrochemical behavior of the ligand and a Ni(II) complex were investigated.

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► ONS type Schiff base and its new transition metal complexes were synthesized.
► Complexes contain pyridine, 4-methylpyridine or 3,5-lutidine in coordination sphere.
► The structures of all the synthesized compounds were confirmed by the spectroscopic techniques.
► A detailed assignment of the spectra and the electrochemical behavior were proposed.