Stability Constants of the Binary Vanadium(III) Complexes with the Aminopolycarboxylic Acids: Nitrilodiaceticpropionic, Nitriloaceticdipropionic, and Nitrilotripopionic Acids Studied by Potentiometric Measurements

We present the results of studies on the stability constants of Vanadium(III) complexes with the aminopolycarboxylic acids: nitrilodiaceticpropionic (NDAP, H 3 L), nitriloaceticdipropionic (NADP, H 3 L), and nitrilotripopionic (NTP, H 3 L) by potentiometric measurements in 3.0 mol·dm −3 KCl ionic medium at 25 °C . The data analysis performed with the LETAGROP computational program indicates the formation of mononuclear complexes of type: VH 3 L 3+ , VH 2 L 2+ , VHL + , VL, V(OH)L − , V(OH) 2 L 2− , and VL 2 3− . The observed order of stability is NDAP > NADP > NTP, due to the changes induced by the acetic propionic group decreasing the stability of the formed complexes. The generated species distribution diagrams are briefly discussed.