Şükriye Güveli

Electrochemistry and structural properties of new mixed ligand nickel(II) complexes based on thiosemicarbazone

Mixed ligand nickel(II) complexes of 5-chloro-2-hydroxybenzophenone-N-R-thiosemicarbazone (R: –CH3 (L1), –CH2–CHCH2 (LII)) and triphenylphosphine were synthesized. The structures of the complexes were characterized by elemental analysis, IR, 1H and 31P NMR spectroscopy, conductivity, electrochemical and magnetic moment measurements, and single-crystal X-ray diffraction technique. The two nickel(II) complexes have a square planar geometry containing O, N, and S atoms of the thiosemicarbazone, and the P atom of triphenylphosphine. The electrochemical behaviors of the thiosemicarbazone ligands and the nickel complexes were studied using cyclic voltammetry and square wave voltammetry. The redox processes of the compounds were significantly influenced by the central metal ions and the nature of the substituents on the thiosemicarbazones, which are the important factors in controlling the redox properties. In situ spectroelectrochemical studies were employed to determine the colors and spectra of the electro-generated species of the complexes.

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

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.