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organic papers
Acta Crystallographica Section E

Structure Reports Online
ISSN 1600-5368

1-Methyl-2-(4-nitrophenyl)imidazo[1,2-a]pyridinium perchlorate: a powder study

Victor B. Babaev,a Sergei G. Vladimir

Rybakov,a* Eugene V. Eduard J. Sonneveld,b Zhukova and V. Chernysheva

a Department of Chemistry, Moscow State University, 119992 Moscow, Russian Federation, and bLaboratory of Crystallography, University of Amsterdam, Nieuwe Achtergracht, 166 Amsterdam, 1018 WV, The Netherlands

The title compound, C14H12N3O2+ÑClO4Ð, crystallizes with two cations and two anions in the asymmetric unit, Z0 = 2. All bond lengths and angles show normal values. Short intermolecular O(perchlorate)ÑÑÑN(imidazole) contacts of 2.94 (3) and À 2.95 (3) A, respectively, indicate the principal location of positive charge near the imidazole N atom in both independent cations. The crystal packing is stabilized by weak intermolecular C HÑÑÑO hydrogen bonds.

Received 9 March 2007 Accepted 15 March 2007

Correspondence e-mail: rybakov20021@yandex.ru

Comment
In continuation of a structural study of imidazo[1,2-a]pyridinium salts (Pointer et al., 1986; Tafeenko et al., 1996), we present here the crystal structure of the title compound, (II), determined from powder diffraction data.

Key indicators Powder X-ray study T = 295 K À Mean (C-C) = 0.043 A R factor = 0.000 wR factor = 0.000 Data-to-parameter ratio = 0.0 For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e.

In compound (II) (Fig. 1), all bond lengths and angles show normal values (Allen et al., 1987). The asymmetric unit consists of two cations and two anions. The mean planes of the bicyclic fragment and the benzene ring in the two independent cations make dihedral angles of 50.7 (9) and 53.2 (9) , which are in agreement with those observed in 1-methyl-2-phenyl-3hydroxymethyl-imidazo[1,2-a]pyridinium chloride (51.4 ; Pointer et al., 1986), 1-methyl-2-phenyl-imidazo[1,2-a]pyridinium iodide (59.4 ; Tafeenko et al., 1996) and 1-methyl-2phenyl-6-nitroimidazo[1,2-a]pyridinium iodide (39.8 ; Tafeenko et al., 1996). Short intermolecular anion cation contacts O11ÑÑÑN1A = À À 2.94 (3) A and O21ÑÑÑN1B = 2.95 (3)A, indicate that the principal location of positive charge is near the imidazole N atom in both independent cations. The crystal packing is stabilized by weak intermolecular C HÑÑÑO hydrogen bonds (Table 1).

Experimental
# 2007 International Union of Crystallography All rights reserved

The title compound was synthesized as described by Babaev & Goncharenko (1998a,b) (see scheme) and recrystallized from a solution in a C2H5OH H2O mixture (1:1 v/v).
doi:10.1107/S1600536807012354 Rybakov et al.


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Figure 1
The asymmetric unit of (II), showing the atom labelling scheme. Displacement spheres are drawn at the 50% probability level.

Figure 2
The Rietveld plot, showing the observed and difference profiles for (II). The reflection positions are shown above the difference profile.

Crystal data
C14H12N3O2+ÑClO4 Mr = 353.72 Orthorhombic, Pbca À a = 31.393 (18) A À b = 25.527 (17) A À c = 7.800 (5) A À V = 6251 (7) A3 Z = 16 Cu K1 radiation À = 1.54059 A = 2.52 mm 1 T = 295 (2) K Specimen shape: flat sheet 7 Ò 7 Ò 1.5 mm Specimen prepared at 293 K Particle morphology: plate, yellowish brown

Data collection
Enraf Nonius Guinier Johannson camera FR 552 diffractometer Specimen mounting: pressed as a thin layer in the specimen holder of the camera Specimen mounted in transmission mode Scan method: fixed Absorption correction: none 2min = 4.0, 2max = 82.8 Increment in 2 = 0.01

Refinement
Rp = 0.049 Rwp = 0.063 Rexp = 0.030 RB = 0.043 S = 2.11 Excluded region(s): 4.04-4.99 Profile function: split-type pseudoVoigt (Toraya, 1986) 2079 reflections 156 parameters 220 restraints H-atom parameters constrained Preferred orientation correction: March Dollase (Dollase, 1986); direction of preferred orientation (001), texture parameter r = 0.93(2)

Table 1

À Hydrogen bond geometry (A, ).
D--HÑÑÑA C3A--H3AÑÑ ÑO13 C3B--H3BÑÑÑO23ii C3B--H3BÑÑÑO18Aiii C6A--H6AÑÑ ÑO12iv C7A--H7AÑÑ ÑO19Bv C15A--H15AÑÑ ÑO24vi
i

D--H 0.93 0.93 0.93 0.93 0.93 0.93

HÑÑÑA 2.37 2.26 2.48 2.17 2.29 2.46

DÑÑ ÑA 3.18 2.99 3.29 2.99 3.17 3.08 (3) (3) (4) (4) (3) (4)
1 2

D--HÑÑ ÑA 145 135 145 146 157 124
; z ? 3; (iv) 2

Symmetry codes: (i) x; y; z 1; (ii) x; y; z ? 1; (iii) x ? 1; y x ? 3; y ? 1; z 1; (v) x; y ? 1; z ? 1; (vi) x ? 1; y ? 1; z ? 1. 2 2 2 2

During the exposure, the specimen was spun in its plane to improve particle statistics. The orthorhombic unit cell dimensions were determined from a Guinier photograph using the indexing

program ITO (Visser, 1969) and refined using the program LSPAID (Visser, 1986) to M20 39 and F30 75 (0.009, 53) using the first 50 peak positions. The space group Pbca was chosen on the basis of systematic extinction rules and confirmed later by the crystal struc ture solution. Intensities for the structure determination and refine ment were measured from the Guinier photographs in 0.01 steps using a Johannson LS18 line scanner. The structure of (II) was solved by the simulated annealing procedure (Zhukov et al., 2001) following the methodology described in detail elsewhere (Chernyshev, 2004). The initial geometry of the cation was optimized by density functional theory calculations performed with the PRIRODA program (Laikov, 1997) employing the B3LYP exchange correlation function (Becke, 1998; Lee et al., 1988). For the representation of the Kohn Sham one electron wave functions, the sets of contracted Gaussian type func tions were used. The contracted patterns were (311/1) for H and (611111/411/11) for C, N and O. Geometry optimization was performed using the quasi Newton method to a final gradient of 3 Ò À 10Ð5 Hartree AÐ1. Simulated annealing was used in a search of possible solutions, varying 24 degrees of freedom for the four rigid units, namely two cations and two perchlorate anions. A unique solution was found and subjected to subsequent bond restrained Rietveld refinement using the program MRIA (Zlokazov & Cher nyshev, 1992) using a split type pseudo Voigt peak profile function (Toraya, 1986) and taking into account anisotropic line broadening (Popa, 1998). The strength of the restraints was a function of inter atomic separation and, for intramolecular bond lengths, corresponds À to an r.m.s. deviation of 0.03 A. Additional restraints were applied to the planarity of three fragments in cations A and B, namely the bicyclic system, the benzene ring and C14/N17/O18/O19. All atoms in the perchlorate anions were refined isotropically, and two overall Uiso parameters were refined for cations A and B, respectively. All H atoms were placed in geometrically calculated positions (C H À 0.93 0.96 A) and allowed to ride on their parent atoms with Uiso(H) À fixed to 0.05 A2. The March Dollase texture formalism (Dollase, 1986), with (001) as the direction of preferred orientation and texture parameter r refined to 0.93 (2), was applied for (II). The diffraction profiles and the differences between the measured and calculated profiles are shown in Fig. 2. Data collection: local program; cell refinement: local program; data reduction: local program; program(s) used to solve structure: MRIA (Zlokazov & Chernyshev, 1992); program(s) used to refine structure: MRIA; molecular graphics: ORTEP 3 (Farrugia, 1997);
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software used to prepare material for publication: MRIA and SHELXL97 (Sheldrick, 1997).
Dollase, W. A. (1986). J. Appl. Cryst. 19, 267 272. Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565. Laikov, D. N. (1997). Chem. Phys. Lett. 281, 151 156. Lee, C. T., Yang, W. T & Parr, R. G. (1988). Phys. Rev. B, 37, 785 789. Pointer, D. J., Wilford, J. B., Hursthouse, M. B. & Walker, N. P. C. (1986). J. Chem. Soc. Perkin Trans. 2, pp. 443 446. Popa, N. C. (1998). J. Appl. Cryst. 31, 176 180. ? Sheldrick, G. M. (1997). SHELXL97. University of Gottingen, Germany. Tafeenko, V. A., Paseshnichenko, K. A. & Schenk, H. (1996). Z. Kristallogr. 211, 457 463. Toraya, H. (1986). J. Appl. Cryst. 19, 440 447. Visser, J. W. (1969). J. Appl. Cryst. 2, 89 95. Visser, J. W. (1986). Powder Diffr. 1, 66 76. Zhukov, S. G., Chernyshev, V. V., Babaev, E. V., Sonneveld, E. J. & Schenk, H. (2001). Z. Kristallogr. 216, 5 9. Zlokazov, V. B. & Chernyshev, V. V. (1992). J. Appl. Cryst. 25, 447 451.

This work was supported by ICDD Grant-in-Aid No. 00 16.

References
Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1 19. Babaev, E. V. & Goncharenko, L. V. (1998a). Pharm. Chem. J. 32, 310 314. Babaev, E. V. & Goncharenko, L. V. (1998b). Khim. Farm. Zh. 6, 24 28. (In Russian). Becke, A. D. (1988). Phys. Rev. A, 38, 3098 3100. Chernyshev, V. V. (2004). IUCr Commission on Powder Diffraction Newsletter, 31, 5 15.

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