Experimental and theoretical spectroscopic study and structural determination of nickel(II) tridentate Schiff base complexes

•Novel nickel Schiff base complexes were prepared and their structures were confirmed by different techniques.•The X-ray crystallography results show that they are four coordinated in the solid state.•DFT calculation of the UV–Visible of the complexes.

Some new complexes of [NiL(PR3)] (where L = (E)-1-[(2-amino-5-nitrophenyl)iminio-methyl]naphthalene-2-olate (L1), (E)-1-[(2-hydroxiphenyl)iminio-methyl]naphthalene-2-olate (L2), R = Bu and Ph) containing tridentate ONN and ONO Schiff bases were synthesized and characterized by IR, UV–Vis, 1H-NMR spectroscopy and elemental analysis. The geometry of [NiL1(PBu3)] and [NiL2(PBu3)] complexes were determined by X-ray crystallography. It was indicated that the complexes have a square planar structure and four coordinates in the solid state. Theoretical calculations were also performed to optimize the structures of the ligands and complexes in the gas phase and ethanol solvent, separately to confirm the structures proposed by X-ray crystallography. In addition, UV–Visible and IR spectra of the complexes were calculated and compared with the corresponding experimental spectra to complete the experimental structural identification.

Graphical abstractSome new tridentate Schiff base complexes of [NiL(PR3)] (where L = (E)-1-[(2-amino-5-nitrophenyl)iminio-methyl]naphthalene-2-olate (L1), (E)-1-[(2-hydroxiphenyl)iminio-methyl]naphthalene-2-olate (L2), R = Bu and Ph) were synthesized and characterized by IR, UV–Vis, 1H-NMR spectroscopy and elemental analysis. The geometry of [NiL1(PBu3)] and [NiL2(PBu3)] were determined by X-ray crystallography. The theoretical calculations were also performed to optimize the structure of ligands and complexes in the liquid and gas phase. The UV–Visible and IR spectra of complexes were calculated.Figure optionsDownload full-size imageDownload as PowerPoint slide