Structure investigations on 4-halo-1,2,3,5-dithiadiazolyl radicals XCNSSN center dot (X = F, Cl, Br): The shortest intradimer S center dot center dot center dot S distance in dithiadiazolyl dimers

Crystals of the 4-halo-1,2,3,5-dithiadiazolyl radicals (X = F, Cl, Br) were obtained by sublimation at 80 degrees C and 10(-2) Torr, and the structures were determined by X-ray diffraction. The fluoro derivative crystallizes as a cisoid dimer in the space group P2(1)/n, whereas the chloro and bromo derivatives crystallize isomorphous as twisted dimers in the space group C2/c. The chloro and bromo derivatives show the shortest intradimer S center dot center dot center dot S contacts of all known 1,2,3,5-dithiadiazolyl dimers. In addition the obtained structure of CICN(2)S(2)center dot represents the fifth polymorph of ClCN(2)S(2)center dot characterized by X-ray crystallography. The structures and the packing including secondary interactions are discussed.