Stacking patterns of thieno[3,2-b]thiophenes functionalized by sequential palladium-catalyzed Suzuki and Heck cross-coupling reactions.

The crystal structures of three 5-alkenyl-2-aryl­thieno[3,2-b]thio­phenes, namely 3,6-di­bromo-5-(4-tert-butyl­styr­yl)-2-(naph­thalen-1-yl)thieno[3,2-b]thio­phene, C28H22Br2S2, (I), 3,6-di­bromo-5-(4-methyl­styr­yl)-2-(naphthalen-1-yl)thieno[3,2-b]thio­phene, C25H16Br2S2, (II), and 3,6-di­bromo-2-(4-tert-butyl­phen­yl)-5-(4-methyl­styr­yl)thieno[3,2-b]thio­phene, C25H22Br2S2, (III), have been determined in order to evaluate the geometry of the mol­ecules. The π-conjugated system containing the thieno[3,2-b]thio­phene skeleton, the ethyl­ene bridge and the phenyl rings is almost planar. The aromatic ring directly attached to the thieno[3,2-b]thio­phene moiety is not coplanar with the thieno[3,2-b]thio­phene moiety itself due to steric hindrance of the bromo substituent. The crystal packings are characterized by π–π stacking [only for (II)] and C—Br⋯π inter­actions. The long axes of the mol­ecules in (I) are oriented in two directions; for the two other structures the long axis is oriented in one direction only.