On the chemistry of iron in biosystems. I. Complex formation between Fe(III) and tartaric acid: a 'core + link' mechanism

The complex formation between Fe(III) and tartaric acid (H2L) has been studied in 0.5 M NaNO3 medium at 25 °C by using potentiometric techniques in the pH range 1.5-4.5. The results, expressed in terms of complex formation reactions, explain the experimental data obtained at different reagent concentrations and model the system taking into account the following reactions and stability constants: {A figure is presented}. The model considered represents a 'core +link' mechanism for the complex formation process. The species FeL acts as a core of the hypothetical link Fe(OH)3L species. The acidity constants of tartaric acid were also determined in separate experiments and used in the analysis of the Fe(III)-tartaric system. Structures are suggested for the complex species formed. © 1987.