Spectral studies and X-ray crystal structures of three nickel(II) complexes of 2-pyridineformamide 3-piperidylthiosemicarbazone

Abstract

Reduction of 2-cyanopyridine by sodium in dry methanol in the presence of 3-piperidylthiosemicarbazide produces 2-pyridineformamide 3-piperidylthiosemicarbazone, HAmpip. Complexes with nickel(II) have been prepared and characterized by magnetic susceptibility and spectroscopic techniques. The crystal structures of [Ni(Ampip) 2], [Ni(Ampip)OAc], and [Ni(HAmpip)Cl]Cl have been solved. Coordination of the anionic and neutral ligand is via the pyridyl nitrogen, imine nitrogen, and thiolato–thione sulfur. [Ni(Ampip) 2] is an approximately octahedral NiN 4S 2 center with the tridentate ligands in a meridonal arrangement. [Ni(Ampip)OAc] is essentially planar except for the acetato ligand, which is >80° out of the coordination plane, and the ionic [Ni(HAmpip)Cl]Cl involves the neutral thiosemicarbazone ligand.