Investigation of adducts of lanthanide and uranium β-diketonates with organophosphorus Lewis bases by supercritical fluid chromatography

Formation of adducts of lanthanide (Ln) and uranium beta-diketonates with neutral donors such as tributyl phosphate, tributyl phosphine oxide or trioctyl phosphine oxide, can greatly improve their SFC behavior. The adduct formation approach leads to the successful separation of lanthanide complexes of the same beta-diketone ligand by SFC using neat CO2 as the mobile phase. Solvation behavior, stability, and stoichiometry of the adducts of lanthanide and uranium beta-diketonates in supercritical fluid were studied by SFC, The molar ratios of the lanthanide-FOD and uranyl-HFA with an organophosphorus reagent are 1:2 and 1:1, respectively, The stability sequence of lanthanide-FOD organophosphorus adducts follows the order Ln(FOD)(3).TOPO>Ln(FOD)(3).2TBPO>Ln(FOD)(3).2TBP. For the Ln-FOD-TBPO system, the relative stability of the adducts increases with the atomic number of lanthanide. (C) 1998 Elsevier Science B.V..