Structure of a new uranyl sulfate hydrate, α-2UO2SO4 7H2O1

Atomic distances, parameters, and angles are tabulated. The uranium is at the center of a pentagonal bipyramid arrangement of oxygen atoms. These are joined in an infinite chain along the b axis by sulfate tetrahedra. The β-form also contains chains made up of very similar units of two bipyramids and two tetrahedra; both forms are illustrated for comparison. The overall structures of these chains are different; in the chain in the α form the units are repeated according to the b-axis translation, while in the β form the replication is by a glide plane. As a result, alternate units in the latter case have reversed orientations. The interatomic distances and angles are comparable in these two forms. The molecular form is 2% smaller in the α form indicating a very slightly more efficient packing. All the water molecules are hydrogen bonded, and distances and angles for these bonds are also tabulated. 1 figure, 3 tables