Syntheses and crystal structures of three barium uranium sulfides

The barium uranium sulfides Ba3.69US6, BaUS3, and BaU2S5 have been synthesized at 1273, 1323, and 1323 K, respectively. The structures of these compounds have been determined by single-crystal X-ray diffraction methods. They crystallize in space groups View the MathML sourceD3d6−R3¯c, View the MathML sourceD2h16−Pnma, and View the MathML sourceC2h5−P21/c, respectively. Among these three ternaries and Ba2US6 the coordination geometries about the U atoms vary considerably. Ba3.69US6 is a mixed U4+/U5+compound whereas the others are U4+ compounds. The decreasing dimensionality of the four compounds with increasing Ba–to–U content shows the expected trend.