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

摘要

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.