A Novel Uranyl Sulfate Cluster in the Structure of Na6(UO2)(SO4)4(H2O)2

A molybdenum(V) monophosphate containing lead has been synthesized for the first time. This new phase Pb3(MoO)3(PO4)5 crystallizes in the Pnma space group with a=14.280(1) ?, b=15.679(1) ?, and c=8.129(1) ?. The crystal structure was refined up to R=0.0406 and Rw=0.0446. The original three-dimensionnal framework of this compound, [Mo3P5O23], can be described by the assemblage of [Mo3P5O28] ribbons running along and forming elliptic tunnels where the Pb2+ cations are located. The topological analogy of this structure with aeschynite is emphasized. The stereoactivity of the 6s2 lone pair of Pb2+ is discussed.