Crystal structure of neptunium(V) sulfate hexahydrate, (NpO2)2SO4 • 6H2O

Single crystals of (NpO2)(2)SO4 center dot 6H(2)O are obtained, and their structure is determined. The structure is built of NpO2+ dioxo cations, SO42- anions, and molecules of coordination and crystallization water. The NpO2+ ions are linked into cationic ribbons stretched along the [001] direction. In the ribbons, neptunoyl ions of one type act as monodentate ligands, whereas neptunoyl ions of the other type coordinate the neighboring neptunoyl groups by two oxygen atoms. The Np(1) and Np(2) atoms have oxygen environments in the shape of a pentagonal bipyramid whose equatorial plane consists of oxygen atoms of the neighboring dioxo cations, sulfate ions. and water molecules. The sulfate ion acts as a bidentate ligand bridging the two neighboring atoms Np(1) and Np(2). Six water molecules are revealed in the structure; one of them is a crystallization water molecule. Hydrogen bonds link cationic ribbons into a three-dimensional network.