Structural Periodicity in Plutonium(IV) Sulfates

The chemistry of tetravalent Pu with sulfate is explored in a series of single-crystal X-ray diffraction studies of the alkali metal plutonium sulfate compounds. Five new structures of Pu(IV) sulfates are presented including the structure for the α-phase of Pu(SO4)2(H2O)4, Na10Pu2(SO4)9(H2O)4, K8Pu2(SO4)8(H2O)5, Rb8Pu2(SO4)8(H2O)4, and Cs4Pu(SO4)4(H2O)2. Changes in structure and stoichiometry are seen down the alkali-metal series despite identical reaction conditions for each of the complexes. Comparison to the other known An(IV) sulfates, Group IV sulfates, and Ce(IV) reveals limited similarity in stoichiometry and structure across the actinide series and their homologues. Marked color changes are observed down the series indicating strong interactions between the plutonium ions and the ligands in these complexes.