Distribution diagrams and stability of alanine coordination compounds of FeII and FeIII.

The formation of mononuclear complexes and a heterovalent compound in the FeII—FeIII—l-Ala—H2O system was observed when using the Clark—Nikolsky oxidation potential at a temperature of 298.15 K and an ionic strength of the (Na(H)ClO4) solution equal to 0.75 mol L−1. The method of successive approximations (iteration) of the Yusupov oxidation function was used to calculate the stability and the model parameters of the mononuclear coordination compounds [FeHL(H2O)5]3+, [Fe(HL)2(H2O)4]3+, [Fe2(HL)2(OH)4(H2O)6]2+, [FeIIIFeII(HL)2(OH)4(H2O)6]+, [FeHL(H2O)5]2+, [Fe(HL)(OH)(H2O)4]+, and [Fe(HL)(OH)2(H2O)3]0 (L is an alanine ligand), the formation constants of these complexes, to determine the regions where they are dominant and their maximum degrees of accumulation, as well as to plot the diagrams of their distribution as a function of pH. It was determined that the heterovalent complex is the most stable and dominates up to pH 9.5. [ABSTRACT FROM AUTHOR]