Hydro-nium bis-(tri-fluoro-methane-sulfon-yl)amide-18-crown-6 (1/1).

The structure of the title compound, HO·CFNOS ·CHO or [HO·CHO][N(SOCF) ], which is an ionic liquid with a melting point of 341-343 K, has been determined at 113 K. The asymmetric unit consists of two crystallographically independent 18-crown-6 mol-ecules, two hydro-nium ions and two bis-(tri-fluoro-methane-sulfon-yl)amide anions; each 18-crown-6 mol-ecule complexes with a hydro-nium ion. In one 18-crown-6 mol-ecule, a part of the ring exhibits conformational disorder over two sets of sites with an occupancy ratio of 0.533 (13):0.467 (13). One hydro-nium ion is complexed with the ordered 18-crown-6 mol-ecule O-H⋯O hydrogen bonds with HOH⋯OC distances of 1.90 (6)-2.19 (7) Å, and the other hydro-nium ion with the disordered crown mol-ecule with distances of 1.85 (6)-2.36 (6) Å. The hydro-nium ions are also linked to the anions O-H⋯F hydrogen bonds. The crystal studied was found to be a racemic twin with a component ratio of 0.55 (13):0.45 (13).