Abstract
The compounds Rh2U6S15, Cs2Ti2U6Se15, Cs2Cr2U6Se15, and Cs2Ti2U6Te15 have been synthesized at 1173 K. All crystallize in space group of the cubic system. Rh2U6S15 has a framework structure with three-dimensional channels. The compounds Cs2Ti2U6Se15, Cs2Cr2U6Se15, and Cs2Ti2U6Te15 have structures similar to that of Rh2U6S15, but with Cs cations variably filling the channels. In all four structures the transition element is octahedrally coordinated by chalcogens and the uranium atom is in a bicapped trigonal-prismatic arrangement. The temperature dependence of the magnetic susceptibility of Cs2Cr2U6Se15 implies both Cr and U magnetic contributions. From these data the compound is not antiferromagnetic, but it could have either a ferrimagnetic or a ferromagnetic ground state.