INVESTIGATION OF ADDUCTS OF LANTHANIDE AND URANIUM BETA-DIKETONATES WITH ORGANOPHOSPHORUS LEWIS-BASES BY SUPERCRITICAL-FLUID CHROMATOGRAPHY

Formation of adducts of lanthanide (Ln) and uranium beta-diketonates w ith neutral donors such as tributyl phosphate, tributyl phosphine oxid e or trioctyl phosphine oxide, can greatly improve their SFC behavior. The adduct formation approach leads to the successful separation of l anthanide complexes of the same beta-diketone ligand by SFC using neat CO2 as the mobile phase. Solvation behavior, stability, and stoichiom etry of the adducts of lanthanide and uranium beta-diketonates in supe rcritical fluid were studied by SFC, The molar ratios of the lanthanid e-FOD and uranyl-HFA with an organophosphorus reagent are 1:2 and 1:1, respectively, The stability sequence of lanthanide-FOD organophosphor us 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 add ucts increases with the atomic number of lanthanide. (C) 1998 Elsevier Science B.V..