STUDIES ON POLYFUNCTIONAL O-LIGANDS - ALKALI AND ALKALINE-EARTH METAL-COMPLEXES OF BUTANETETRACARBOXYLATE IN AQUEOUS-SOLUTION

Formation and stability of Na+, K+, Mg2+, Ca2+ complexes of 1,2,3,4-bu tanetetracarboxylic acid have been studied potentiometrically (H+-glas s and ISE-Ca electrodes), in aqueous solution, at 25-degrees-C and dif ferent ionic strengths (0 less-than-or-equal-to I less-than-or-equal-t o 1.21 mol/l). The species ML, MLH, MLH2, MLH3, M2L and M2LH have been found (for Na+ and K+ also the species M3L). Measurements in mixed so dium-calcium solutions, showed that the mixed metal complexes CaNaL an d CaNaLH are also formed. The relative formation constants have been r eported and critically discussed.