Cs 3 UP 2 S 8 , a Coordination Polymer Containing the Unprecedented [U=S] 2+ Sulfidouranium(2+) Moiety

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. Cs 3 UP 2 S 8 , is the first actinide compound containing a terminal M =S group. It was synthesized by reacting uranium metal, Cs 2 S, S, and P 2 S 5 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. Cs 3 UP 2 S 8 crystallizes in the rhombohedral space group R $\bar{3}$ [ a = 15.5217(8) Å; c = 35.132(2) Å, V = 8305.0(8) Å 3 , 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.