P1: KVK Journal of Chemical Crystallography (JOCC) pp1416-jocc-497718 October 26, 2004 11:17 Style file version Nov. 07, 2000 FOR PROOFREADING ONLY Journal of Chemical Crystallography, Vol. 34, No. 12, December 2004 ( C  2004) Synthesis and crystal structure elucidation of 1-(4-fluorobenzyl)-2-(4-cyanophenyl)-1H- benzimidazole-5-carbonitrile S. ¨ Ozbey, (1)∗ F.B. Kaynak, (1) H. G ¨ oker, (2) and C. Ku¸ s (2) Received July 10, 2004 The synthesis and spectral identification of 1-(4-fluorobenzyl)-2-(4-cyanophenyl)-1H- benzimidazole-5-carbonitrile (1) have been reported. IR, 1 H NMR, and EI mass spectral analysis were used for its spectral identification. The structure of 1 was confirmed by X- ray crystallographic studies. Intramolecular hydrogen bond occurs between the imidazole nitrogen and one of hydrogen of the florobenzene. The crystal packing is governed by C H···N intermolecular hydrogen bonds. The molecular structure observed in crystal and the optimised geometries at the HF level by doing semi-empirical and ab initio calculations were compared. KEY WORDS: Benzimidazole derivative; synthesis; X-ray structure; theoretical calculations. Introduction Up to dates, a variety of benzimidazoles have been discovered and approved to be use- ful in the treatment of many diseases. Can- desartane, telmisartane, emedastin, mizolastin, omeprazole and its analogs e.g. pantoprazole, and rabeprazole are highly new examples. Position and type of the substituents on the benzimida- zole ring are responsible for the variety of biologi- cal activity, including antimicrobial, 1 antifungal, 2 anticancer, 3 antihelmentic, 4 antiallergic, 5 and antioxidant. 6 Meanwhile, in one of our previous studies, we reported the synthesis and potent antifungal (1) Department of Engineering Physics, Faculty of Engineering, Hacettepe University, Beytepe, Ankara 06800, Turkey. (2) Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Ankara University, Tando˘ gan, Ankara 06100, Turkey. ∗ To whom correspondence should be addressed; e-mail: sozbey@ hacettepe.edu.tr. activities of a series of 2-substituted-phenyl-1H- benzimidazole-5-carbonitrile derivatives. Among them, compounds having butyl/propyl and car- bonitrile substituents at C1 and C5/C6 po- sition of 2-(4-fluorophenyl)-1H-benzimidazole displayed potent antifungal activity against Can- dida sp., close to the popularly used antifun- gal agent, fluconazole. These results prompt us to synthesize new benzimidazole-nitrile com- pounds. Meantime, we have previously re- ported the crystal structures and some spectral properties of different type of benzimidazole derivatives. 7-11 This paper deals synthesis, spectroscopic properties, and single crystal X-ray study of a new benzimidazole compound, 1-(4-fluorobenzyl)- 2-(4-cyanophenyl)-1H-benzimidazole-5-carboni- trile. In addition we compared the molecular structure observed in crystal and the optimised ge- ometries at the HF level by doing semi-empirical and ab initio calculations. From the comparison 853 1074-1542/04/1200-0853/0 C  2004 Springer Science+Business Media, Inc.