Synthesis, crystal structure and DFT calculations of octahedral nickel(II) complexes derived from <i>N</i>′-[(<i>E</i>)-phenyl(pyridin-2-yl)methylidene]benzohydrazide

<p>The two new nickel(II) complexes, [Ni(HL)(L)](NO₃)∙H₂O (<b>1</b>) and [Ni(L)₂] (<b>2</b>) (where HL/L = <i>N</i>′-[(<i>E</i>)-phenyl(pyridin-2-yl)methylidene]benzohydrazide), have been synthesized and characterized by elemental analysis, spectroscopic, magnetic susceptibility, and cyclic voltammetric measurements. Single-crystal X-ray analysis of [Ni(HL)(L)](NO₃)∙H₂O (<b>1</b>) and [Ni(L)₂] (<b>2</b>) has revealed the presence of a distorted octahedral geometry around nickel(II). The X-ray and spectral characterizations have confirmed the existence of the keto-enol form of the ligands in the complexes. The electronic structures and spectral properties of the ligands and the complexes have been explained by DFT and TDDFT calculations. Superoxide dismutase activity of these complexes has also been measured.