Two polymorphs of bis(4-benzoylthio-1,3-dithiole-2-thione)-5,5-disulphide

Reaction of caesium 4-benzoy1-1,3-dithiole-2-thione-5-thiolate with iodine produced bis(4-benzoylthio1,3-dithiole2-thione)-5,5'-disulfide, 6. Compound, 6 has been obtained in two crystalline forms, on recrystallisation from different organic solvent systems, designated 6X with space group P2(1)/c and 6Y with space group P2(1). Two enantiomers of the molecule of 6 are observed but both polymorphs are racemates, 6X because of the centro-symmetric space group P2(1)/c. and 6Y because of the presence of both enantiomers in the bimolecular asymmetric unit. The polymorphs differ in molecular packing, the resulting intermolecular contacts and the disposition of the enantiomers. In 6X the enantiomers are found in separate stacks of face to face molecules which combine to create channels containing intermolecular C-H center dot center dot center dot O hydrogen-bonds along with pi center dot center dot center dot pi overlap of rings within and between the stacks. In 6Y the enantiomers are found in separate chains with intermolecular C-H center dot center dot center dot S hydrogen-bonds providing connnectivity within and between the chains and, overall, two-dimensional connectivity in well defined layers of molecules. Stacking of the layers creates stacks of face to face molecules similar to, but less regular than those observed in 6X, in which the enantiomers alternate along the length of the stack.