Stabilization of Highly Reactive “Naked Anions”: Synthesis, Crystal Structure and Vibrational Spectrum of [Na(12‐crown‐4) 2 ] 2 [P 2 S 6 ] · CH 3 CN

The novel thiodiphosphate, [Na(12‐crown‐4) 2 ] 2 [P 2 S 6 ] · CH 3 CN, bis[di(12‐crown‐4)sodium] hexathiodiphosphate(V) acetonitrile solvate ( 1 ) has been synthesized by the reaction of Na 2 [P 2 S 6 ] with 12‐crown‐4 in dry acetonitrile. The title compound crystallizes in the tetragonal space group P4 2 /mbc (no. 135), with a = 15.184(1) Å, c = 21.406(2) Å and Z = 4 and final R1 = 0.0671 and wR2 = 0.0809. The crystal structure is characterized by discrete sodium‐bound crown‐ether sandwich cations, [Na(12‐crown‐4) 2 ] + and [P 2 S 6 ] 2− ions with D 2h symmetry. Sodium ion is coordinated by the eight oxygen atoms of two crown‐ether molecules to form a square antiprisma. Solvent molecules of CH 3 CN are statistically disordered. Distances and angles of the [P 2 S 6 ] 2− unit are similar to those in [K(18‐crown‐6)] 2 [P 2 S 6 ] · 2 CH 3 CN, and in K 2 [P 2 S 6 ] and Cs 2 [P 2 S 6 ]. The FT‐Raman and FT‐IR spectrum of the title compound has been recorded and interpreted, especially with respect to the P 2 S 6 group and in comparison to the few known metal hexathiodiphosphates(V).