Crystal structure of 4,4'-bis-(4-bromo-phen-yl)-1,1',3,3'-tetra-thia-fulvalene.

The mol-ecule of the title compound, C(18)H(10)Br(2)S(4), has a C-shape, with C (s) mol-ecular symmetry. The dihedral angle between the planes of the di-thiol and phenyl rings is 8.35†(9)°. In the crystal, mol-ecules form helical chains along [001], the shortest inter-actions being π⋯S contacts within the helices. The inter-molecular inter-actions were investigated by Hirshfeld surface analysis. Density functional theory (DFT) was used to calculate HOMO-LUMO energy levels of the title compound and its trans isomer.