Correlation of complexation rate constants of 1:1 iron chelates with ligand dissociation constants.: Food considerations

Iron which is present as a trace species in foods and drinks is very important to the young infant for normal growth and development. Nutritional status of iron may affect the metabolism of other nutrients. Iron chelates have been shown to have a significant beneficial effect on metal status by increasing metal bioavailability in human diets. From a study of the complexation of iron(III) with a series of structurally similar dicarbonylic ligands in aqueous solution, thermodynamic and kinetic parameters have been obtained The existence of an essential reaction mechanism throughout the series has been proved The established correlation suggests that complexation rates of a structurally similar 1:1 chelate of iron(III) may be predicted from the ligand dissociation constant. Thus, an achievable objective might be to develop quantitative scales of ligand ionization degree for predicting expected behavior of complexation reactions. Since the differences observed in the rates of complex formation are not a result of steric effects but of changes in the metal-ligand electron density, a free-energy relationship has been obtained for the complexation reactions.