Formation of Self-Complementary Halogen-Bonded Dimers

The X-ray structure of a series of iodo- and bromo-phenylethynylpyridines designed to form self-complementary dimers in the solid state are reported. The perfluoroiodo- and perfluorobromophenylethynyl derivatives, 3-[(2-bromo-3,4,5,6-tetrafluorophenyl)ethynyl]pyridine, 3-[(2,3,4,5-tetrafluoro-6-iodophenyl)ethynyl]pyridine, 2-[(3-bromo-2,4,5,6-tetrafluorophenyl)ethynyl]pyridine, and 2-[(2,4,6-trifluoro-3,5-diiodophenyl)ethynyl]pyridine, formed self-complementary halogen-bonded dimeric units in the solid state. In contrast, 3-[(2-bromo-4,5-difluorophenyl)ethynyl]pyridine formed a C-H...N hydrogen-bonded dimer.