Vanadium(III) complexes in aqueous solution with the dicarboxylic oxalic, malonic and succinic acids

The complex species formed in aqueous solution (25 degreesC, I = 3.0 mol.dm(-3) KCl ionic medium) between V3+ cation and the dicarboxylic acids oxalic, malonic and succinic (H,L) 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 V3+ ion, indicates that under the experimental conditions employed the complexes [VHL](2+), [VL](+), [V(OH)L], [V(OH)(2)L](.), [VL2](-), [V(OH)L-2](2-), [VL3](3-) and [V(OH)L-3](4-) with oxalic acid, the complexes [VHL](2+), [VL](+), [VL2](-), [V(OH)L-2](2-), [V(OH)(2)L-2](3-), [VL3](3-) and [V(OH)L-3](4-) with malonic acid, and the [VL](+) and [V(OH)L] complexes with succinic acid were formed. The stability constants of the complexes formed were determined.