Stability Constants of Rare Earths with Violuric Acids

Abstract

AbstractThe metal ligand stability constants of violuric acid [H2VA], N‐methyl violuric acid [H2MVA], N‐phenyl violuric acid [H2PVA] and N‐(o‐m‐p) tolyl violuric acids [N‐H2(o‐m‐p)TVA] with La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III), Gd(III), Dy(III), and Ho(III) have been determined potentiometrically in 50 Vol% ethanol water media at 25°C and at an ionic strength of 0.1 M NaClO4. The stability of the complexes follow the order of basicities of ligands and also the electron affinities of rare earths as measured by their overall ionisation potential. The order of stabilities of rare earths with violuric acids is,La3+ < Ce3+ < Pr3+ < Nd3+ < Sm3+ < Gd3+ < Eu3+ < Dy3+ < Ho3+.