Crystal structures of 3-halo-2-organochalcogenylbenzo[b]chalcogenophenes

The structure of the title compounds 3-bromo-2-(phenyl­sulfan­yl)benzo[b]thiophene (C14H9BrS2; 1), 3-iodo-2-(phenyl­sulfan­yl)benzo[b]thio­phene (C14H9IS2; 2), 3-bromo-2-(phenyl­selan­yl)benzo[b]seleno­phene (C14H9BrSe2; 3), and 3-iodo-2-(phenyl­selan­yl)benzo[b]seleno­phene (C14H9ISe2; 4) were determined by single-crystal X-ray diffraction; all structures presented monoclinic (P21/c) symmetry. The phenyl group is distant from the halogen atom to minimize the steric hindrance repulsion for all structures. Moreover, the structures of 3 and 4 show an almost linear alignment of halogen–selenium–carbon atoms arising from the intra­molecular orbital inter­action between a lone pair of electrons on the halogen atom and the anti­bonding σ*Se–C orbital (nhalogen→σ*Se–C). This inter­action leads to significant differences in the three-dimensional packing of the mol­ecules, which are assembled through π–π and C—H⋯π inter­actions. These data provide a better comprehension of the inter­molecular packing in benzo[b]chalcogenophenes, which is relevant for optoelectronic applications.