Abstract
1-(4-Nitrilo-2,3,5,6-tetrafluorophenyl)benzimidazole, 2, and 1-(2,3,5,6-tetrafluoropyridyl)-2-methyl-benzimidazole, 4, crystallize in the polar space groups Cc and Pca2(1), respectively. Both structures arise from pi-pi stacking interactions. For 2 the stacking gives rise to columns of alternating complementary rings that are approximately orthogonal. For 4 the stacking leads to parallel columns, with the polarity arising from the arrangement of the resulting sheets of molecules, between which there are no pi-pi stacking interactions. The syntheses of2 and 4 and related perfluoroarylbenzimidazoles are also reported. (C) 2014 Elsevier B.V. All rights reserved.