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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.