Stabilization of U5+ in Rb4U4P4Se26. An actinide compound with a mixed selenophosphate/polyselenide framework and ion-exchange properties

The advancement of the polychalcophosphate flux technique in recent years has resulted in many novel quaternary thiophosphate and selenophosphate compounds. Here we report the Rb{sub 4}U{sub 4}P{sub 4}Se{sub 26}, a novel three-dimensional, ion-exchange material containing the rare U{sup 5+} ion. Pentavalent uranium compounds are relatively scarce because of uranium`s strong tendency to disproportionate to U{sup 4+} and U{sup 6+}. Therefore, they are of fundamental importance since U{sup 5+} has the simplest 5f-electron configuration [Rn]5f{sup 1}, and are useful in understanding the behavior of the electrons of actinide ions. 20 refs., 2 figs.