Solution phase coordination chemistry of trivalent lanthanide and actinide cations with Bis(2,4,4-trimethylpentyl)dithiophosphinic acid

Abstract

The structure and stoichiometry of the complexes between trivalent lanthanide (Nd3+ and Sm3+) and actinide (Am3+ and Cm3+) cations and bis(2,4,4-trimethylpentyl)dithiophosphinic acid have been studied in various organic diluents. The coordination numbers and metal-ligand bond distances are the same for the lanthanide and actinide complexes despite the great selectivity of this ligand for the trivalent actinides. When the aggregation of the extractant in the organic phase is taken into account, the data from liquid-liquid extraction experiments, small-angle neutron scattering, visible absorption spectroscopy, and the extended X-ray absorption fine structure all support the presence of 1:3 metahligand complexes in the organic phase. The cations studied appear to be small enough relative to the steric constraints of the ligands that 1:4 metabligand complexes are not stable. © 2002 Atomic Energy Society of Japan.