VANADIUM(III) COMPLEXES IN AQUEOUS SOLUTION WITH THE DICARBOXYLIC OXALIC, MALONIC AND SUCCINIC ACIDS

Abstract

The complex species formed in aqueous solution (25 °C, I = 3.0 mol.dm-3 KCl ionic medium) between V 3+ cation and the dicarboxylic acids oxalic, malonic and succinic (H2L) have been studied potentiometrically. The application of the least-squares computer program LETAGROP to the experimental (emf H) data, taking into account the hydrolytic species of V 3+ ion, indicates that under the experimental conditions employed the formation of the complexes [VHL] 2+ , [VL] + , [V(OH)L], [V(OH)2L] - , [VL2] - , [V(OH)L2] 2- , [VL3] 3- and [V(OH)L3] 4- with oxalic acid, [VHL] 2+ , [VL] + , [VL2] - , [V(OH)L2] 2- , [V(OH)2L2] 3- , [VL3] 3- and [V(OH)L3] 4- with malonic acid, [VL] + and [V(OH)L] with succinic acid. The stability constants of the complexes formed were determined.