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

Abstract

AbstractThe novel uranium thiophosphate CsLiU(PS4)2has been synthesized by reacting uranium metal, Cs2S, Li2S, S, and P2S5at 700 °C in an evacuated silica tube. The crystal structure was determined by single‐crystal X‐ray diffraction techniques. CsLiU(PS4)2crystallizes in the rhombohedral space groupR$\bar{3}$c(a= 15.2797(7) Å;c= 28.778(2) Å,V= 5818.7(5) Å3,Z= 18). The structure ofCsLiU(PS4)2is a unique three‐dimensional U(PS4)22–framework with large tunnels with an approximate diameter of 6.6 Å running parallel to the crystallographiccaxis. 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)2the uranium atoms are coordinated by thiophosphate groups in a pseudotetrahedral fashion, and the PS4groups act as linear connectors. Topologically, CsLiU(PS4)2may be regarded a chalcogenide analogue of silicate frameworks, with the uranium atoms and PS4groups replacing silicon and oxygen atoms. Alternatively, CsLiU(PS4)2may 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. Theμeffof 2.83 μBat 300 K is in agreement with an f2configuration of U4+.