ANALYTICAL SCIENCES 2006, VOL. 22 2006 © The Japan Society for Analytical Chemistry x109 X-ray Structure Analysis Online Crystal and Molecular Structure of 1,3-Diethyl-2-oxo-4,6-diphenyl-1,2,3,4tetrahydropyridine-3-carbonitrile Urmila H. PATEL,*† Mukesh M. JOTANI,** and Hetal C. SHAH*** *Department of Physics, Sardar Patel University, Vallabh Vidyanagar, Gujarat, 388120, India **Physics Department, Bhavan’s R. A. College of Science, Khanpur, Ahmedabad, Gujarat, 380001, India ***Xavier’s Research Foundation, St. Xavier’s College Campus, Navrangpura, Ahmedabad,380009, India In the molecular structure, both of the phenyl rings are twisted considerably out of the plane of the central tetrahydropyridine (THP) ring which itself being puckered to adopt a twist boat conformation. The ethyl moiety at pyridine N1 stands vertical, while the moiety at the 3-position of pyridine N1 is coplanar to the THP plane. An intermolecular C–H·O interaction influences the molecular packing. (Received December 5, 2005; Accepted February 7, 2006; Published on web April 20, 2006) 2-Pyridine systems are a class of compounds that exhibit a large Tetrahydropyridine spectrum of biological activities.1 derivatives are found to adopt an interesting stereochemistry along with possessing very powerful analgesic, antiinflamatory, catharlic and antihistaminic properties. The moloecular structure of the title compound, 1,3-diethyl-2-oxo-4,6-diphenyl1,2,3,4-tetrahydropyridine-3-carbonitrile, is one of the series of such substituted tetrahydropyridine derivative that is being investigated by us as a part of systematically studying the THP derivatives. Earlier, we reported also its dimethyl, dibenzyl derivatives.3,4 A schematic diagram of the molecule is shown in Fig. 1. Rectangular transparent crystals of the compound are grown by recrystallization from ethanol by slow evaporation. The crystal density is measured by a flotation method in an aqueous potassium iodide solution. The crystal and experimental details are given in Table 1. The structure was solved by direct methods and refined by full- matrix least squares. All of the non-hydrogen atoms were refined anisotropically and the H atoms were allowed to ride on the parent atom in the model. The atomic coordinates of non-hydrogen atoms are presented in Table 2. An ORTEP plot of the molecule with atom numbering scheme is shown in Fig. 2. The molecular structure consists of a 2-oxo-3-cyano Fig. 1 † Schematic diagram of the molecule. To whom correspondence should be addressed. E-mail: u_h_patel@yahoo.com tetrahydropyridine ring with two phenyl rings and two ethyl groups connected to it. Steric interactions due to substituents of different sizes at THP may be attributed to an opening up of the angles C1–N1–C5 (121.10(16)˚) and N1–C5–C4 (121.13(18)˚) and in the abnormality of the C1–N1 (1.371(2)Å) and C2–C3 (1.562(3)Å) bond lengths. The six-membered central THP ring is very much distorted and puckered to assume a twist boat conformation.2 A similar distorted geometry of THP ring is also Table 1 Crystal and experimental data CCDC NO. Empirical formula Formula weight Crystal system Space group Unit cell dimensions Z V T Dx Dm µ Radiation (Mo Kα) F(0 0 0) θ range for data collection Reflections used for refinement Number of parameters Goodness-of-fit Final R indices [I > 2σ (I)] R indices all data (∆/σ )max (∆ρ )max (∆ρ )min Measurement Programme system Structure determination Refinement Graphics 294954 C22H22N2O 330.42 monoclinic P21/c a = 8.9443(16)Å b = 22.421(4)Å c = 9.3023(17)Å β = 97.290(4)˚ 4 1850.4(6)Å3 293(2)K 1.186 Mg/m3 1.196 Mg/m3 0.073 mm–1 λ = 0.71073 Å 704 1.82 to 28.39˚ 4343 226 1.054 R1 = 0.0723 wR2 = 0.164 R1 = 0.1089 wR2 = 0.182 0.001 0.364 eÅ–3 –0.173 eÅ–3 Bruker SMART CCD SMART SHELXS-97 SHELXL-97 PLATON x110 ANALYTICAL SCIENCES 2006, VOL. 22 Table 3 Selected bond lengths (Å), bond angles (˚) and torsional angles (˚) Fig. 2 level. ORTEP diagram of the molecule at the 50% probability Table 2 Atomic coordinates and equivalent displacement parameters for the non-hydrogen atoms Atom x y z isotropic Ueq phenyl ring stands vertical with the best THP plane (89.86(6)˚), which is also observed in the dibenzyl derivative (89.57(5)˚).4 The other six-membered phenyl ring is oriented at 56.40(9)˚ to THP plane, the angle is 49.21(9)˚ and 49.20(6)˚ in its analogous derivatives.3,4 Torsional angles C1–N1–C21–C22 = 84.5(2)˚ and C3–C2–C19–C20 = –178.7(2)˚ reveal orthogonal and coplanar conformations of the respective ethyl moieties with respect to THP plane. The notable diffrence in the orientation of two ethyl groups may be attributed to the involvment of ethylene carbon C21 in relatively weak, but significant, van der Waal type of intermolecular interaction, while the other ethyl moiety does not participate in any such interaction. In the absence of a conventional hydrogen bond, the packing of the molecular structure is controlled mainly by an intermolecular C–H·O interaction and a few significant short van der Waal contacts. The symmetry-related molecules at 1–x, –y, 1–z are arranged in such a way that they form a dimmer involving oxygen O1 and phenyl carbon C9, where C9·O1 = 3.489(3)Å, H9·O1 = 2.58 Å and C9–H9·O1 = 167˚. Acknowledgements The authors are thankful to Department of Physics, SPU for the financial support to carry out the work, and are grateful to the late Dr. C. G. Dave of Organic Syntheses Laboratory, M. G. Science Institute, Ahmedabad, Gujarat, India for academic support of this work. Ueq = (1/3)ΣiΣjUij(ai*aj*)(ai·aj). observed in dimethyl and dibenzyl derivatives.3,4 The ringpuckering parameters of the central THP ring are summarized as follows, with the values of dimethyl and dibenzyl derivatives, respectively, given inside the brackets. q2 = 0.4182(19)Å (0.4572(17) and 0.4261(15)Å) q3 = 0.2223(19)Å (0.2317(17) and 0.2252(15)Å) Q = 0.4732(19)Å (0.5126(17) and 0.4819(15)Å) q = 62.0(2)˚ (63.12(19) and 62.14(18)˚) f = 136.6(3)˚ (214.4(2) and 223.3(2)˚) The cyano moiety, as observed in other structures,3–6 remains linear with respect to the THP plane. The para-substituted References 1. B. Vacher, B. Bonnaud, P. Funes, N. Jubault, W. Koek, A. Marie-Bernadette, C. Cosi, and M. Kleven, J. Med. Chem., 1999, 42, 1648. 2. D. Cremer and J. A. Pople, J. Am. Chem. Soc., 1975, 97, 1354. 3. U. H. Patel, C. G. Dave, M. M Jotani, and H. C. Shah, Acta Cryst., 2002, C58, o191. 4. U. H. Patel, C. G. Dave, M. M Jotani, and H. C. Shah, Z. Kristallogr., New Cryst. Struct., 2002, 217, 29. 5. S. N. Black, R. J. Davey, A. M. Z. Slawin, and D. J. Williams, Acta Cryst., 1992, C48, 323. 6. Z. Hussain, F. F. Fleming, R. E. Norman, and S. Chang, Acta Cryst., 1996, C52, 1010.