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RESEARCH PRODUCT

Modular Metal Chalcogenide Chemistry: Secondary Building Blocks as a Basis of the Silicate-Type Framework Structure of CsLiU(PS4)2

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The novel uranium thiophosphate CsLiU(PS4)2 has been synthesized by reacting uranium metal, Cs2S, Li2S, S, and P2S5 at 700 °C in an evacuated silica tube. The crystal structure was determined by single-crystal X-ray diffraction techniques. CsLiU(PS4)2 crystallizes in the rhombohedral space group Rc (a = 15.2797(7) A; c = 28.778(2) A, V = 5818.7(5) A3, Z = 18). The structure ofCsLiU(PS4)2 is a unique three-dimensional U(PS4)22– framework with large tunnels with an approximate diameter of 6.6 A running parallel to the crystallographic c axis. The tunnels are filled with Cs+ cations. The smaller Li+ cations are located at tetrahedral sites at the periphery of the channels. In the structure of CsLiU(PS4)2 the uranium atoms are coordinated by thiophosphate groups in a pseudotetrahedral fashion, and the PS4 groups act as linear connectors. Topologically, CsLiU(PS4)2 may be regarded a chalcogenide analogue of silicate frameworks, with the uranium atoms and PS4 groups replacing silicon and oxygen atoms. Alternatively, CsLiU(PS4)2 may be viewed as a coordination polymer, which is formed in salt melts by the solid state equivalent of the “self-assembly” reactions in solution. Magnetic susceptibility measurements indicated Curie–Weiss-type behavior between 4 K and 300 K. The μeff of 2.83 μB at 300 K is in agreement with an f2 configuration of U4+.