Synthesis and crystal structure studies of 5-(trifluoromethyl)-1,3,4-thiadiazol-2(3 H )-one at 180 K

The synthesis and crystal structure of C 3 HF 3 N 2 OS, systematic name 5-(trifluoromethyl)-1,3,4-thiadiazol-2(3 H )-one (5-TMD-2-one), a compound containing the pharmacologically important heterocycle 1,3,4-thiadiazole, is presented. The asymmetric unit comprises six independent molecules ( Z ′ = 6), all of which are planar. The r.m.s. deviations from each mean plane range from 0.0063 to 0.0381 Å, not including the CF 3 fluorine atoms. Within the crystal, two of the molecules form hydrogen-bonded dimers that in turn combine with inversion-related copies to form tetrameric constructs. Similar tetramers, but lacking inversion symmetry, are formed by the remaining four molecules. The tetramers are linked into tape-like motifs by S...O and O...O close contacts. The environments of each symmetry-independent molecule were compared via a Hirshfeld surface analysis. The most abundant atom–atom contacts are between fluorine atoms, while the strongest result from N—H...O hydrogen bonds.