title: The chemistry of iron in biosystems-V Study of complex formation between iron(III) and tartaric acid in alkaline aqueous solutions.
abstract: Complex formation between Fe(III) and tartaric acid (H(2)L) has been studied in O.5M NaNO(3) medium at 25 degrees by potentiometry at pH 4.5-11. The following complex species and corresponding values of the stability constants (charges omitted) are proposed: 2Fe + 2L + 5H(2)O --> Fe(2)(OH)(5)L(2) + 5H(+); log* beta(-522) = 4.95 Fe + L + 3H(2)O --> Fe(OH)(3)L + 3H(+); log* beta(-311) = -1.55 Fe + L + 5H(2)O --> Fe(OH)(5)L + 5H(+); log* beta(-511) = -21.2 These results are in good agreement with those reported for this system in acid. The results may be presented as the degeneration of the "core + link" mechanism observed in the acidic zone. Structures are suggested for the complex species formed.
authors.affiliation: Departament de Quimica, Collegi Universitari de Girona (UAB), Pça. Hospital 6, 17071 Girona, Spain.
authors.forename: V
authors.initials: V
authors.lastname: Salvado
authors.forename: X
authors.initials: X
authors.lastname: Ribas
authors.forename: M
authors.initials: M
authors.lastname: Valiente