Crystal and molecular structure of 5-benzylidene-2-thiohydantoin: The S…S intermolecular interactions between two CS groups

The crystal structure of 5-benzylidene-2-thiohydantoin, C10H8N2OS, the precursor of annelated arylidene-2-thiohydantoin derivatives with the micromolar affinity to the benzodiazepine receptor, has been determined at 293 K and 120 K. The title molecule in Z-configuration is planar within experimental error. Among two bonds between N1/N3 and C2(sp2), N3C2 is evidently longer than the N1C2 one. In the structure determined at 120 K difference equals 0.019 Å. For that reason, in the cycloaddition reaction N3 nitrogen was privileged and the products of 2,3-substitution were obtained at a significantly higher yield than the 1,2-substitution ones. The chain of molecules joined by NH…O hydrogen bonds created the main structure motive in the crystal. Hydrogen bond of NH…S and intermolecular interactions of S…S were noticed between two chains. With respect to the center of symmetry, sulfur atoms are 3.414(1) Å and 3.3745(8) Å apart at ambient and low temperatures, respectively. The related S…S contacts, shorter than the sum of van der Waals' radii, were identified in many species deposited in CSD, all with cyclic and/or non-cyclic arrangements of CS. The statistical analysis of the geometrical distribution for such contacts suggests that there is a maximum of probability for collinear CS…SC orientations. Additionally, if NH is located in close proximity of CS substituent, this contact is self-assembled with NH…S weak hydrogen bonds.