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

Abstract

Although terminal chalcogeno ligands are well known for the group 5 and 6 transition metals, they are highly unusual for the oxophilic group 4 metals and unknown so far for the lanthanides or actinides. Cs3UP2S8, is the first actinide compound containing a terminal M=S group. It was synthesized by reacting uranium metal, Cs2S, S, and P2S5 in a 4:1:8:3 ratio at 700 °C in an eutectic LiCl/CsCl mixture. The crystal structure was determined by single‐crystal X‐ray diffraction techniques. Cs3UP2S8 crystallizes in the rhombohedral space group R$\bar{3}$ [a = 15.5217(8) Å; c = 35.132(2) Å, V = 8305.0(8) Å3, Z = 18]. The crystal structure is based on a tetrahedral network type, wherein the uranium atoms are coordinated by a unusual sulfido moiety and thiophosphate groups in a pseudo‐tetrahedral fashion. The U=S distance of 2.635(3) Å observed in the sulfide moiety is approx. 0.2 Å shorter than the average U–S single bond length, indicating a double‐bond type character.

Synthesis and Properties of Uranium Sulfide Cations. An Evaluation of the Stability of Thiouranyl, {S═U═S}2+

“…Uranium persulfide compounds, in which uranyl is coordinated by bidentate persulfide groups, exhibit analogy with previously reported uranyl peroxide compounds . The compound Cs 3 UP 2 S 8 comprises a terminal US bond, which is referred to as a “thiouranyl unit”; however, because this is a uranium(IV) compound and there is no {SUS} 2+ moiety, it is not thiouranyl per se. Another complex comprising a terminal US bond has recently been reported with a U–S bond distance of 2.48 Å, which is ∼0.6 Å longer than the corresponding terminal UO bond distance but only ∼0.1 Å longer than the US distance in the {OUS} 2+ complex .…”

Comprehensive Uranium Thiophosphate Chemistry: Framework Compounds Based on Pseudotetrahedrally Coordinated Central Metal Atoms

“…Still, in the chalcogen-rich systems the chalcogen's ability to catenate has led to formal oxidation state assignments beyond 4+ in Rb 5 U 4 P 4 Se 26 = Rb 4 (U 5+ ) 4 (PSe 4 3-) 4 P(Se 2 2-) 4 (Se 2-) 2 , [11] which are still object of discussion. [12] Whereas binary or ternary uranium (and actinide) chalcogenides [13][14][15][16][17][18][19][20][21][22] and quaternary uranium (and actinide) chalcophosphates A a U x P y Q z , [23][24][25][26][27][28][29][30][31][32] many of which are accessible from reactive polychalcogenide fluxes, [33] are reasonably well characterized, our information concerning the corresponding ternary compounds U x P y Q z is scarce. [34] We have observed in the initial report [35] of the research described herein in full that the tetrahedral network compound U(P 2 S 6 ) 2 is formed by the reaction of U, P 2 S 5 , and S. Herein the uranium atoms are coordinated by the chalcogeno moieties in a pseudotetrahedral manner with thiophosphate groups acting as linear connectors between the central metal atoms.…”

Synthesis, Structure, and Spectroscopy of Two Ternary Uranium(IV) Thiophosphates: UP2S9 and UP2S7 Containing P2S92– and P2S72– Ligands

“…The structural relationships between P 2 S 7 4– and P 2 S 8 4– thiophosphate are good examples of this. , Cyclic structures are also known that incorporate polysulfide linkages, such as the S 3 group in P 2 S 8 4– . , Compounds containing multiple types of thiophosphates have also been found and these include A 4 Ti 2 (P 2 Q 9 ) 2 (P 2 Q 7 ) ( A = K, Rb; Q = S, Se) and Cs 8 U 5 (P 3 S 10 ) 2 (PS 4 ) 6 . While there are more than two dozen of quaternary actinide thiophosphate representatives, ,,,, very few ternary phases are known. ,, …”