Crystal structure of 4,5-bis(2-bromineethylsulfanyl)-1,3-dithiole-2-thione, C7H8Br2S5

Abstract

Source of materialTo a solution of 4,5-bis(2-hydroxyethylsulfanyl)-1,3-dithiole-2-thione [1] (2.86 g, 10 mmol) and CBr 4(8.3 g, 25 mmol) in dichloromethane (100 ml) was drop-added a solution of PPh 3 (6.56 g, 25 mmol) in the same solvent (20 ml) within 2 hours. The mixture was stirred at room temperature for 7 hours. The resulting solution was washed with water and dried over Na 2SO4. The solvent was then evaporated under reduced pressure and the crude product was purified by column chromatography (dichloromethane : petroleum ether = 2 : 3) to afford the title compound as yellow solid. DiscussionDuring the past decades, tetrathiafulvalene (TTF) and its derivatives (TTFs) as building blocks in both conducting molecular materials and supramolecular chemistry [2-4] have been attracted increasing attention since the discovery of the first metallic charge transfer (CT) complex between TTF and 7,7,8, [5]. On account of the hybrid organic-inorganic materials, CT salts based on TTFs have been widely investigated in the search for new and improved superconducting CT complexes and radical cation salts [6,7].TTFs serve as important p-electron donors for the development of molecular-based organic metals and superconductors, and a variety of studies on modification of the TTF skeleton have been made [8][9][10]. There are many routes for the preparation of TTFs. Generally, the most widely used is the coupling of two identical or non-identical 1,3-dithiole-2-(thi)ones mediated by a trivalent phosphorus derivative [11]. As important precursors of TTF derivatives, 1,3-dithiole-2-thiones have also attracted attention [12]. In the molecule of the title compound, the bond lengths and angles are within normal ranges [13]. In the crystal structure, adjacent molecules are linked by weak intermolecular C−H···S interactions (C···S distances: 3.7676(4) and 3.7932(4) Å, respectively) [14] into a chain, which extends into a two dimensional supramolecular architecture via weak inter-chain interactions of Br···Br (Br···Br distances: 3.731(1) and 3.889(1) Å, respectively) [13]. The adjacent layers are further interconnected into a interleaved three-dimensional supramolecular architecture by weak interactions of S···S and Br···S, with S···S distance range from 3.527(2) to 3.796(2) Å and a Br···S distance of 3.700(2) Å [13]. In addition, dipole-dipole and van der Waals interactions are also effective in the molecular packing.