title: 4,7-bis(4-pyridylethynyl)-2,1,3-benzothiadiazole and its dipyridinium diperchlorate.
abstract: The title compound, C20H10N4S, and its dipyridinium salt, 4,4'-(2,1,3-benzodiazol-4,7-diyldiethynyl)dipyridinium diperchlorate, C20H12N4S2+*2ClO4-, display bond alternation in the 2,1,3-benzothiadiazole rings, which suggests their quinonoid character. The dipyridinium dication molecules stack along the a axis and form a dimer with short S.N interheteroatom contacts [3.146 (4) A] between the two 1,2,5-thiadiazole rings. The dimer is surrounded by the perchlorate anions with which it forms a large number of intermolecular N-H...O and C-H...O hydrogen bonds.
authors.affiliation: Department of Structural Molecular Science, The Graduate University for Advanced Studies, Myodaiji, Okazaki 444-8585, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Akhtaruzzaman
authors.forename: M
authors.initials: M
authors.lastname: Tomura
authors.forename: Y
authors.initials: Y
authors.lastname: Yamashita