Hydrogen-bonded and π-stacked nickel(II) thiosemicarbazone complexes: Synthesis, spectral and structural studies

Abstract

Mixed ligand Ni(II) complexes were synthesized from triphenylphosphine and S-methyl- or S-ethyl-isothiosemicarbazone ligands derived from 3-bromo-5-chloro-2-hydroxy-benzaldehyde. The complexes were characterized by physicochemical and spectroscopic methods. In addition, their molecular structures were determined by single-crystal X-ray diffraction. In both complexes, the Ni atom has a near square-planar geometry, being coordinated by the phenolato oxygen, azomethine nitrogen and amine nitrogen atoms of the thiosemicarbazone ligands, together with the phosphorus atom of the triphenylphosphine. The S-methyl complex includes an additional free thiosemicarbazone ligand in the asymmetric unit. X-ray analysis shows that O–H···N, N–H···N, C–H···N and C–H···O-type hydrogen bonds and π–π stacking interactions are responsible for stabilizing the crystal structures.