A spectroscopic and kinetic investigation on the substitution of Fe(III) for Ni(II) in a siderophore model

Abstract

A kinetic and spectroscopic study was performed on the substitution of Fe(III) by Ni(II) in the water soluble anion [Fe(L1-) 2L2-]-, a siderophore model (L-= dopa-semiquinone and L2- = dopacatecholate). The reaction was followed in the UV/vis range through the appearing of an intense band at 592 nm due to the anion complex [Ni(L1-)3]- formed which also presents a resonance Raman effect. The overall reaction obeyed a zero-order rate law at 25, 35, 45, and 50°C, and the rate constants and thermodynamic parameters have been obtained. A chemometric study based on the Imbrie Q-type factor analysis revealed that the reaction occurred with only one kind of intermediate whose UV/vis spectrum has been calculated. © 2007 Verlag der Zeitschrift für Naturforschung.