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

The structure of the title compounds 3-bromo-2-(phenyl-sulfan-yl)benzo[ b ]thiophene (C 14 H 9 BrS 2 ; 1 ), 3-iodo-2-(phenyl-sulfan-yl)benzo[ b ]thio-phene (C 14 H 9 IS 2 ; 2 ), 3-bromo-2-(phenyl-selan-yl)benzo[ b ]seleno-phene (C 14 H 9 BrSe 2 ; 3 ), and 3-iodo-2-(phenyl-selan-yl)benzo[ b ]seleno-phene (C 14 H 9 ISe 2 ; 4 ) were determined by single-crystal X-ray diffraction; all structures presented monoclinic ( P 2 1 / 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 intra-molecular orbital inter-action between a lone pair of electrons on the halogen atom and the anti-bonding σ* Se-C orbital ( n halogen →σ* Se-C ). This inter-action leads to significant differences in the three-dimensional packing of the mol-ecules, which are assembled through π-π and C-H⋯π inter-actions. These data provide a better comprehension of the inter-molecular packing in benzo[ b ]chalcogenophenes, which is relevant for optoelectronic applications.