Acta Cryst. (2005). E61, o4116-o4118  [ doi:10.1107/S1600536805036536 ]

Polymorph of 1H-benzimidazole

S. Krawczyk and M. Gdaniec

Abstract: A second orthorhombic polymorph () of 1H-benzimidazole, C₇H₆N₂, metastable at room temperature, has been obtained. It has a melting point of 431 K and a crystal density of 1.27 Mg m^-3. At room temperature, the crystals transform into the well known orthorhombic form, with a melting point of 445 K. In both polymorphs, benzimidazole molecules are connected into polymeric chains via N-HN hydrogen bonds. However, the mode of aromatic ring interactions differs significantly in the two crystalline forms. In the form, the molecules show edge-to-face interactions, whereas in the new form, a sandwich-herringbone arrangement of the aromatic molecules is observed.

Online 16 November 2005

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