Kinetics of the base hydrolysis of iron (II) complexes with pyridyl–quinolyl Schiff base ligands in aqueous and aqueous/methanol binary mixtures

Abstract

Kinetics of the reactivity against OH− ion of some novel bis-N,N′,N″-(pyridin-2-ylmethylene-quinolin-8-yl) Schiff base iron (II) iodide (1), bis-N,N′,N″-[(1-pyridin-2-yl-ethylidene)-quinolin-8-yl] Schiff base iron (II) iodide (2) and bis-N,N′,N″-[(phenyl-pyridin-2-ylmethylene)-quinolin-8-yl] Schiff base iron (II) iodide (3) have been studied spectrophotometrically. A relevant tentative mechanism was suggested with respect to the rate law of the base hydrolysis in aqueous media and aqueous/methanol binary mixtures. The reaction revealed pseudo first-order kinetics with a rate law k obs = k 2[OH−]. The rate trends and activation parameters are consistent with the complexes’ stability discussed according to the hydrophobicity/hydrophilicity of the substituent groups (R) in the complexes. The co-organic solvent, i.e., methanol, has a positive impact on the rate of base hydrolysis.