Bipyridylacetylenes 1: the synthesis of some bipyridylacetylenes via the palladium-catalyzed coupling of acetylenes with 2,2′-dibromobipyridyl, and the single crystal X-ray structure of 6,6′-bisphenylethynyl-2,2′-bipyridine

Abstract

The synthesis of a series of 6,6′-diethynyl-2,2′-bipyridyls from the palladium-catalyzed coupling of 6,6′-dibromo-2,2′-bipyridine with a series of arylacetylenes is reported. The single crystal X-ray structure of 6,6′-phenylethynyl-2,2′-bipyridyl was determined. Crystal data: monoclinic, A2/a, with cell constants a = 10.0385(4), b = 9.2166(4), c = 21.4130(8) Å, and β = 102.981(3)°; Dcalc. = 1.226 g cm−3, Z = 4, Rf = 0.045, S = 1.22, using 886 reflections of the 1443 unique reflections. The packing diagram indicates essentially that the molecules pack in a layered assembly with the nitrogen atoms of the dipyridyl groups on opposite sides and with a dihedral angle of 59.85(16)° between the pyridyl and phenyl groups. The acetylenic bond distances are normal. Key words: acetylene, palladium, catalysis, coupling, monomers, crystal structure.