Crystal structures of 4-PhCOS-5-RS-1,2-dithiole-3-thione (R = Me and PhCH2), 4,5-(MeS)2-1,2-dithiole-3-thione and 3,4,5-(MeS)3-1,2-dithiolium iodide

The crystal structures of the molecular dmt compounds, 4,5-bis(methylthiolato)-1,2-dithiole-3-thione, (1), 4-benzoylthiolato-5-methylthiolato-1,2-dithiole-3-thione, (3) and 4-benzoylthiolato-5-benzylthiolato-1,2-dithiole-3-thione, (4), and the organic salt, 3,4,5-tris(methylthiolato)-1,2-dithiolium iodide (2) have been determined at 120 K. The packing of the molecules provides a variety of intermolecular, or interion, contacts. Notable features in 1 and 3 are the columns of overlapping dithiole rings. In both cases the columns are propagated in the direction of h and neighbouring rings are related to one another by the operation of crystallographic centres of symmetry. In 2 weak C-H center dot center dot center dot I (H center dot center dot center dot I = 3.0236 and 3.0166 angstrom) and C-H center dot center dot center dot S (H center dot center dot center dot S = 2.8660 angstrom) hydrogen-bonds, contacts with short I center dot center dot center dot S distances (3.433 and 3.370 angstrom) and a C-H center dot center dot center dot pi contact, with the dithiole ring as acceptor (H center dot center dot center dot Cg = 2.946 angstrom), create zig-zag chains propagated in the direction of h which are further connected to form corrugated sheets parallel to (0 0 1) with methyl groups on their surfaces. Intermolecular Q center dot center dot center dot S-thiole contacts much shorter than the sum of the contact radii (3.32 angstrom) of oxygen and sulphur are present in 3 and 4. The formation of 3 or 4 occurred regiospecifically from successive reactions of 4,5-bis(benzoylthiolato)-1,2-dithiole-3-thione with one equivalent of caesium hydroxide and RI (R = Me or PhCH2).