Complex formation of indium(III) with citric acid in aqueous solution

Complex formation of In3+ ion with citric acid in an aqueous solution was studied by pH-metric titration at the molar ratio of the reactants [In3+] : [H(4)Cit] = 1 : 1, 1 : 2, and 1 : 3 in a range of.. 2-10. The mathematical simulation of equilibria in an indium(III)-citric acid system was performed using the CPESSP program package. The formation of 1 : 1, 1 : 2, and 1 : 3 indium(III) citrate complexes with different degrees of nuclearity and protonation was established. The equilibrium constants of formation of the complexes were calculated. The predomination of the polynuclear indium(III) citrate complexes at the equimolar metal to ligand ratio of was observed in almost the whole pH range studied (3-10).