organic papers o2128 Karaca et al. C 21 H 27 N 3 2+ 2Cl H 2 O doi:10.1107/S1600536805018337 Acta Cryst. (2005). E61, o2128–o2130 Acta Crystallographica Section E Structure Reports Online ISSN 1600-5368 1-Benzyl-3-[2-(1-piperidinio)ethyl]benzimidazolium dichloride monohydrate Selvi Karaca, a Mehmet Akkurt, a * U ¨ lku ¨ Yılmaz, b Hasan Ku ¨c¸u ¨kbay b and Orhan Bu ¨yu ¨kgu ¨ngo ¨r c a Department of Physics, Faculty of Arts and Sciences, Erciyes University, 38039 Kayseri, Turkey, b Department of Chemistry, Faculty of Arts and Sciences, I ´ no ¨nu ¨ University, 44280 Malatya, Turkey, and c Department of Physics, Faculty of Arts and Sciences, Ondokuz Mayıs University, 55139 Samsun, Turkey Correspondence e-mail: akkurt@erciyes.edu.tr Key indicators Single-crystal X-ray study T = 100 K Mean (C–C) = 0.002 A ˚ R factor = 0.031 wR factor = 0.078 Data-to-parameter ratio = 17.4 For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e. # 2005 International Union of Crystallography Printed in Great Britain – all rights reserved The title compound, C 21 H 27 N 3 2+ 2Cl H 2 O, was synthesized from 1-benzylbenzimidazole and 2-chloroethylpiperidine hydrochloride in dimethylformamide. In the cation, the benzimidazole ring is connected to the piperidine ring by an ethylene group. The crystal structure is stabilized by O— HCl, N—HCl, C—HO and C—HCl hydrogen- bonding interactions. Comment Heterocyclic compounds generally exhibit versatile pharma- cological activities, such as antitumour, diuretic, fungicidal, bactericidal, antihelmintic, antiallergic, vasodilator, anti- histaminic and local analgesic. We have reported the synthesis and antimicrobial activities of many benzimidazole derivatives (Ku ¨c ¸u ¨ kbay et al. , 2003, 2004) and elucidated the crystal structures of some benzimidazole derivatives having piper- idine or morpholine groups (Tu ¨ rktekin et al., 2004; Akkurt, Tu ¨ rktekin et al., 2004; Akkurt, O ¨ ztu ¨rk et al., 2004; Akkurt et al., 2005). We now report the synthesis and crystal structure of a biologically interesting piperidine-substituted benzimidazole compound, (I). The molecular structure of (I) is illustrated in Fig. 1, and selected bond distances and angles are given in Table 1. All the geometric parameters of (I) agree with the results obtained in our previous studies of related heterocycles (Akkurt et al., 2005; Tu ¨ rktekin et al., 2004). The benzimidazole ring is essentially planar, with maximum deviations of 0.012 (1) A ˚ for atom N1 and 0.012 (1) A ˚ for atom C6. The dihedral angle between the planes of the phenyl and benzimidazole ring systems is 72.83 (6) . The piperidine ring has a chair confor- mation [the puckering parameters (Cremer & Pople, 1975) are Q T = 0.5701 (18) A ˚ , = 177.12 (18) and ’ = 195 (4) ]. The crystal structure of (I) is stabilized by O—HCl, N— HCl, C—HO and C—HCl hydrogen-bonding inter- actions. Details are given in Table 2 and the hydrogen-bonding involving the Cl1 anion and the water molecule of crystal- lization, O1, is illustrated in Fig. 2. Received 8 June 2005 Accepted 9 June 2005 Online 17 June 2005