Crystal structure of 4-phenyl-1,2-dithia-3,5-diazole dimer

Abstract

4-Phenyl-1,2-dithia-3,5-diazolium chloride on reduction with thiocyanate ion gives the black air-sensitive title compound, (PhCN₂S₂)₂. Crystals have been studied by means of X-ray diffraction at room temperature. The compound crystallizes in the space group P2₁2₁2₁(no. 19) with a= 16.061(1), b= 32.984(5), and c= 5.774 0(4)Å, and Z= 8. The crystal structure has been solved using 2 513 reflections and refined to a final R value of 0.082. Each asymmetric unit contains two (PhCN₂S₂)₂ molecules. Within each dimer the bridging mean S ⋯ S distance is 310.9(5)pm. The two half-molecules within each dimer are nearly parallel and are slightly twisted with respect to each other. The short (mean) CN₂S₂ ring distances (d_CN= 133, d_SN= 162, d_SS= 209 pm) and the PhCN₂S₂ coplanarity suggest that the rings are aromatic with one electron pair delocalized at the four (disulphide) sulphur atoms.