AbstractThe novel thiodiphosphate, [Na(12‐crown‐4)2]2[P2S6] · CH3CN, bis[di(12‐crown‐4)sodium] hexathiodiphosphate(V) acetonitrile solvate (1) has been synthesized by the reaction of Na2[P2S6] with 12‐crown‐4 in dry acetonitrile. The title compound crystallizes in the tetragonal space group P42/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 [P2S6]2− ions with D2h symmetry. Sodium ion is coordinated by the eight oxygen atoms of two crown‐ether molecules to form a square antiprisma. Solvent molecules of CH3CN are statistically disordered. Distances and angles of the [P2S6]2− unit are similar to those in [K(18‐crown‐6)]2 [P2S6] · 2 CH3CN, and in K2[P2S6] and Cs2[P2S6]. The FT‐Raman and FT‐IR spectrum of the title compound has been recorded and interpreted, especially with respect to the P2S6 group and in comparison to the few known metal hexathiodiphosphates(V).