Complexing of plutonium with alkylenediphosphine dioxides

The distribution coefficients of Pusup((4)), Pusup((6)) and Pu((3)) are measured in the case of their extraction from nitric acid solutions with five alkylenediphosphine dioxides (ADPD). In each case the effective extraction constants are determined. It has been found that the complexes are disolvates and monosolvates and the acido complexes are extracted together with Pu(NO3). During extraction of Pusup((3)) with ADPD as in the case with other trivalent actinoids and lanthanides, an anomalous dependence of the stability of the complexes on the structure of ADPD takes place: the replacement of alkyl substituent groups by more electronegative phenyl groups (when the basicity of ADPD decreases) results, not in a decrease, but in an increase in the stability of the complexes