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

Abstract

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 R$\bar{3}$c (a = 15.2797(7) Å; c = 28.778(2) Å, V = 5818.7(5) Å3, 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 Å 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+.

Cs3UP2S8, a Coordination Polymer Containing the Unprecedented [U=S]2+ Sulfidouranium(2+) Moiety

“…Figure 2 illustrates that each U 4+ is eight‐coordinate. Two bidentate PS 4 3– ligands and one tridentate P 2 S 6 4– ligand (which replaces one of the four bidentate thiophosphate ligands in the crystal structures of U(P 2 S 6 ) 2 28 and CsLiU(PS 4 ) 2 ,29 respectively) surround the uranium atom in a pseudo‐tetrahedral fashion. The fourth position in this pseudo‐tetrahedral coordination is occupied by a terminal sulfido ligand.…”

“…For the lanthanides or actinides the M = Q ( Q = S, Se, Te) moiety is unknown. The U=S distance of 2.635(3) Å is approximately 0.2 Å shorter than the average U–S distances of 2.843 Å in CsLiU(PS 4 ) 2 29 and U(P 2 S 6 ) 2 ,28 slightly shorter than a Th=S distance of 2.743 Å,25 but significantly longer than the M =S ( M = Nb, Ta) distances of 2.196 and 2.204 Å in [ M 6 S 17 ] 4– 34 or the Zr=Te distance of 2.650 Å in [Zr(Te){TeSi(SiMe 3 ) 3 } 2 dmpe 2 ],35 if the differences of the ionic radii of Zr 4+ (0.97 Å), Nb 5+ (0.69 Å) and U 4+ (0.87 Å), S 2– (1.84 Å) and Te 2– (1.87 Å) are taken into account. Still, the difference of approximately 0.2 Å between the U=S and U–S bridging distances is in good agreement with the M =S and M –S bridging distances typically observed for group 5 chalcogenides.…”

“…The structures of the title compound Cs 3 UP 2 S 8 and the uranium thiophosphates U(P 2 S 6 ) 2 ,28 CsLiU(PS 4 ) 2 ,29 and other framework compounds like TaPS 6 ,41 A Ti 2 (PS 4 ) 3 ( A = Li, Na, Ag),42 A Nb 2 P 2 S 12 ( A = K, Rb, Cs),43 Ag 2 NbTi 2 P 6 S 25 ,44 A 11 U 7 (PS 4 ) 13 ( A = K, Rb),45 or Ln 4 (GeS 4 ) 3 ( Ln = Ce, Nd)46–48 indicate that many uranium – and in an analogoues fashion early transition metal – thiophosphates might conceptually be assembled by a simple LEGO‐type approach according to the following recipe: (i) the uranium atoms act as pseudotetrahedral centers of connectivity, (ii) the bi‐ or tridentate thiophosphate ligand groups take the role of rod‐like connectors, (iii) the general assemblage of corner sharing U(thiophosphate) 4 pseudotetrahedra follows the rules established for silicate networks. (iv) The structure of Cs 3 UP 2 S 8 presents an extension to these simple guidelines as the terminal =S moiety may substitute for a thiophosphate group but – as a terminal ligand – represents a dead end in the above connectivity pattern.…”

“…Besides U(P 2 S 6 ) 2 ,28 CsLiU(PS 4 ) 2 ,29 and A 11 U 7 (PS 4 ) 13 ( A = K, Rb)45 the structures of several other actinide chalcophosphates have been reported, namely Rb 4 U 4 (PSe 4 ) 3 (Se 2 ) 3 (Se),50 A 2 ThP 3 Se 9 ( A =K, Rb, Cs)51 Rb 4 U 2 (P 2 Se 6 ) 2.5 (Se 2 ),52 as well as Cs 8 U 5 (P 3 S 10 ) 2 (PS 4 ) 6 ,53 K 10 Th 3 (P 2 S 7 ) 4 (PS 4 ) 2 ,53 and A 5 An (PS 4 ) 3 , ( A = K, Rb, Cs; An = U, Th) 53. Although the latter ones share some features with the title compound, they differ in various respects.…”

Synthesis and Crystal Structure of Cs2U2(P2Se9)(Se2)2

“…Reported examples include the ternaries ThP 2 S 6 , UP 2 S 6 , U(P 2 S 6 ) 2 , UP 2 S 7 ,, UP 2 S 9 , and U 3 (PS 4 ) 4 ; the quaternaries Cs 4 Th 4 P 4 Se 26 , Rb 4 U 2 P 5 Se 17 , Rb 4 U 4 P 4 Se 26 , A 2 ThP 3 Se 9 ( A = K, Rb), Cs 4 Th 2 P 5 Se 17 , A 11 U 7 (PS 4 ) 13 ( A = K, Rb), CsLiU(PS 4 ) 2 , Cs 8 U 5 (P 3 S 10 ) 2 (PS 4 ) 6 , A 5 An (PS 4 ) 3 ( A = K, Rb, Cs and An = U, Th), Cs 4 Th 2 P 6 S 18 ; AkAn (PS 4 ) 2 ( Ak = Sr, Ba and An = U, Th); and the quintary A 6 U 3 Sb 2 P 8 S 32 …”