Synthesis, characterization and bio-activity of nickel(II) and copper(II) complexes of a bidentate NS Schiff base of S-benzyl dithiocarbazate

The reaction of S-benzyldithiocarbazate (SBDTC) with 3-hydroxyacetophenone afforded a bidentate NS Schiff base HL (HL = benzyl-3-(3-hydroxyphenyl methyl ethylene)hydrazine carbodithioate) which on further reaction with nickel(II) and copper(II) salt yielded bis-chelated inner complexes, NiL₂ and CuL₂, respectively with deprotonated L ligand. The ligand and its complexes were characterized by physico-chemical techniques, viz., molar conductance, magnetic susceptibility measurement, IR, NMR, UV-Vis spectroscopy and mass spectroscopic techniques. The crystal structure of all the compounds was also characterized by single crystal X-ray crystallography. The ligand exists in its thione tautomeric form both in solution and in the solid state. In the complexes the two deprotonated ligands chelate the metal through the azomethine nitrogen and the thione sulfur atom with cis arrangement generating a tetrahedrally distorted square planar geometry around the metal center. Only complex CuL₂ showed moderate analgesic activity at 60 min compared to Diclofenac sodium, while all the test compounds exhibited good anti-inflammatory activity as compared to standard drug Indomethacin.