An octahedral nickel(II) complex of a hexadentate N2O2S2 thioether ligand: synthesis, characterization, X-ray and electronic structure

A hexadentate dibasic thioether N2O2S2 donor ligand (H 2 L) and its octahedral nickel(II) complex, [Ni(L)] have been synthesized and characterized by physicochemical and spectroscopic techniques. The structures of both H 2 L and its nickel complex were confirmed by single-crystal X-ray diffraction studies. The cyclic voltammogram of the complex shows a quasi-reversible Ni(II)/Ni(III) oxidation couple (E 1/2 = 0.88 V) along with a ligand-based reduction (E 1/2 = −0.83 V). The electronic structures and electrochemical properties have been interpreted with the help of DFT calculations. The electronic transitions as calculated by TDDFT/CPCM method are used to assign the UV–Vis absorption bands.