Homo- and Heteroligand Nickel(II) Complexes with Benzoic and para-Methoxybenzoic Acid Hydrazides and L-Histidine

Abstract

Complex formation of nickel(II) with benzoic, para-methoxybenzoic acid hydrazides, and L-histidine have been studied by the methods of pH-metric titrimetry, spectrophotometry, and mathematical modelling in aqueous solutions with 1.0 mol dm–3 KNO3 as background at 298 K. Dissociation constants of ligands, as well as composition, formation constants, and spectral parameters of homo- and heteroligand complexes have been determined. It has been shown that stability of the complexes formed with para-methoxybenzoic acid hydrazide is higher than with benzoic acid hydrazide, which is consistent with the electron-donor properties of the methoxy group. Extra stabilization of the nickel(II) heteroligand complexes with benzoic (para-methoxybenzoic) acid hydrazide and L-histidine has been discovered and interpreted.

Keywords

• pH-metry
• spectrophotometry
• mathematical modelling
• complex formation
• nickel(II)
• benzoic acid hydrazide
• para-methoxybenzoic acid hydrazide
• L-histidine