Acta Crystallographica Section C

Crystal Structure Communications

Volume 57, Part 11 (November 2001)

Acta Cryst. (2001). C57, 1343-1348 [doi:10.1107/S010827010101397X]

Indole- and carbazole-substituted pyridinium iodide salts: a rare case of conformational isomerism in crystals

Z. Wang, V. N. Nesterov, O. Ya. Borbulevych, R. D. Clark, M. Yu. Antipin and T. V. Timofeeva

Abstract: A series of indole- and carbazole-substituted pyridinium iodide salts has been synthesized and characterized. X-ray analysis revealed that the iodide salt of the indole-substituted cation (E)-4-(1H-indol-3-ylvinyl)-N-methylpyridinium (IMPE⁺), C₁₆H₁₅N₂⁺·I^-, (I), has two polymorphic modifications, (Ia) and (Ib), and a hemihydrate structure, C₁₆H₁₅N₂⁺·I^-·0.5H₂O, (II). Until now, only one crystal modification has been identified for the (E)-4-(9-ethyl-9H-carbazol-3-ylvinyl)-N-methylpyridinium (ECMPE⁺) iodide salt, C₂₂H₂₁N₂⁺·I^-, (III). Crystals of (Ia) and (Ib) comprise stacks of antiparallel cations with iodide anions located in the channels between the stacks. Due to the presence of the water molecules, the packing in (II) is quite different to that found in (Ia) and (Ib), and positional disorder involving a statistical superposition of two rotamers of IMPE⁺, with different orientations of the indole fragment, was found. Crystals of (III) contain two independent ECMPE⁺ rotamers with different orientations of their carbazole substituents. The cations are packed in stacks, with the iodide anions located in the channels between the stacks. In (III), the iodide was found to be disordered over two sites, with occupancies of 0.83 and 0.17.

Formula: C₁₆H₁₅N₂⁺·I^-, C₁₆H₁₅N₂⁺·I^-·0.5H₂O and C₂₂H₂₁N₂⁺·I^-

Online 13 November 2001


	Structure factor file (CIF format) (142.4 kbytes) Contains datablock Ia

	Structure factor file (CIF format) (159.2 kbytes) Contains datablock Ib

	Structure factor file (CIF format) (329.2 kbytes) Contains datablock II

	Structure factor file (CIF format) (435.3 kbytes) Contains datablock III

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