Synthesis and X-Ray Analysis of Isomeric Diazadithia-Pentacenes

The isomeric diazadithiapentacenes (3) and (4) were obtained in re-actions of 2-chloro-3-bromoquinoline (5) with selected sulfur reagents in various conditions. The 1,4-dithiin ring opening in diazadithiapentacene (3) led to 2,3'-diquinolinyl sulfide or (via the Smiles rearrangement stage of the S(registered trademark)S type) to 3,3'-diquinolinyl sulfide or to diazadithiapentacene (4) depending on reaction conditions. The X-Ray study of pentacenes (3) and (4) revealed non-planar and folded structures along the central sulfur-sulfur axis. The central six-membered ring is in a boat conformation.