Solvent extraction of metal ions with mixed ligands—V: Adduct formation of some tris-TTA complexes

Abstract

The adduct formation of the tris-TTA complexes of In 3+, Sc 3+, La 3+, Lu 3+ and Am 3+ ions have been studied by liquid-liquid distribution. The following equilibrium constants for the distribution and adduct formation have been determined at 25°C: M 3+ (aq) + 3HA (org) ⇌ MA 3 (org) + 3H + (aq); K ex MA 3 (org) + n L (org) ⇌ MA 3L n (org); β n where the chelating acid, HA, is 2-thenoyltrifluoroacetone (TTA), and the neutral ligands, L, are tributylphosphate (TBP), dibutylsulfoxide (DBSO) and methylisobutylketone (hexone). The organic solvent was carbon tetrachloride and the aqueous phase was 1 M (H, Na)ClO 4. The values of K ex and β x are given in Tables 1 and 2. InA 3 does not form adducts. ScA 3 adds one TBP but no hexone, LaA 3, EuA 3, LuA 3 and AmA 3 add two molecules of TBP forming adducts which are more stable than the ScA 3 adduct. The formation constants of the MA 3(TBP) 2 adducts showed an order of stability LaA 3 > EuA 3 ≅ LuA 3. DBSO gives similar results to TBP, but the adducts with hexone are less stable than those with TBP.