Infrared spectroscopic study of nickel complexes with salen-type ligands and their polymers

Abstract

In this work, a series of the monomeric and polymeric complexes of nickel (II) with N2O2 Schiff base ligands were investigated by Fourier Transform Infrared (FTIR) spectroscopy. In these complexes, the molecular structure was modulated by peripheral substitution affecting the electronic and steric properties of the compounds. The complexes with donor and acceptor substituents in the phenolate moieties were examined. Also, the diimine backbone was varying by aliphatic and aromatic groups, the latter is in conjugation with the phenolate moieties. The empirical band assessment was supported by theoretical modeling of the infrared spectra at the DFT level of theory. Infrared spectra–structure correlations for metal complexes were found. A complete set of vibrational characteristics for all complexes was determined as well as vibrational properties for the diimine bridge and substituents in the phenolate moieties.