Crystal structure, configurational and DFT study of nickel(II) complexes with N2O-donor type Schiff base ligand

Nickel(11) complexes containing a Schiff base (L) derived from 2-pyridinecarboxyldehyde and 2-furoic hydrazide [Ni(HL)(L)]NO3 (1) and [Ni(L)(2)](4)H2O (2) where HL = N'-[(E)-pyridin-2-yl-methylidene]furan-2-carbohydrazide, have been synthesized and comprehensively characterized via physico-chemical techniques as well as by single crystal X-ray structural analysis. In both the complexes, the ligand behaves as mono-anionic tridentate and binds to the nickel(II) ion via deprotonated carbonyl-oxygen, pyridine-nitrogen and azomethine-nitrogen. Magnetic moments and electronic studies suggest an octahedral geometry around nickel(II) ion in both the complexes. The supramolecular architecture in both (1) and (2) are shown by C-H center dot center dot center dot pi and pi center dot center dot center dot pi. interactions. The molecular structures and spectral properties of the complexes have been explained by DFT and TD-DFT calculations. The electronic excitation energies of these complexes, calculated at TD-DFT levels, are in agreement with values deduced from the experimental UV-visible spectra.