Spectral and structural studies of nickel(II) complexes of salicylaldehyde 3-azacyclothiosemicarbazones

Abstract

Mononuclear nickel(II) complexes with two ONS donor thiosemicarbazone ligands {salicylaldehyde 3-hexamethyleneiminyl thiosemicarbazone [H 2L 1] and salicylaldehyde 3-tetramethyleneiminyl thiosemicarbazone [H 2L 2]} have been prepared and physico-chemically characterized. IR and electronic spectra of the complexes have been obtained. The thiosemicarbazones bind to the metal as dianionic ONS donor ligands in all the complexes except in [Ni(HL 1) 2] ( 1). In compound 1, the ligand is coordinated as a monoanionic (HL −) one. The magnetic susceptibility measurements indicate that all the complexes are mononuclear and are diamagnetic. The complexes were given the formulae [Ni(HL 1) 2] ( 1), [NiL 1py] ( 2), [NiL 1α-pic] ( 3), [NiL 1γ-pic] · H 2O ( 4), [NiL 2py] ( 5) and [NiL 2γ-pic] ( 6). The structures of compounds 2 and 3 have been solved by single crystal X-ray crystallography and were found to be distorted square planar in geometry with coordination of azomethine nitrogen, thiolato sulfur, phenolato oxygen and pyridyl nitrogen atoms.