2-Methyl­imidazolium picrate

Grzegorz Dutkiewicz; S Samshuddin; B Narayana; H S Yathirajan; Maciej Kubicki

doi:10.1107/S1600536810053390

. 2010 Dec 24;67(Pt 1):o235. doi: 10.1107/S1600536810053390

2-Methylimidazolium picrate

Grzegorz Dutkiewicz ^a, S Samshuddin ^b, B Narayana ^b, H S Yathirajan ^c, Maciej Kubicki ^a,^*

PMCID: PMC3050384 PMID: 21522735

Abstract

In both ionic components of the title salt, C₄H₇N₂ ⁺·C₆H₂N₃O₇ ⁻, the rings are approximately planar; the maximum deviation from the mean plane is an order of magnitude larger in the picrate ring [0.0289 (10) Å] than in the imidazolium ring [0.0028 (10) Å. The nitro groups are twisted with respect to the six-atom ring plane; the NO₂ groups next to the oxide O atom, at the 2- and 6-positions, are twisted more [by 53.59 (9) and 18.46 (12)°] than the NO₂ group at the 4-postition, for which the twist angle is 7.28 (16)°. In the crystal, N—H⋯O hydrogen bonds, in which the hydroxyl O atom acts as a double acceptor and one of the O atoms from a nitro group acts as an additional acceptor, connect molecules into chains along the c-axis direction. Relatively short C—H⋯O contacts and π–π interactions between symmetry-related six-membered rings [centroid–centroid distances = 3.5938 (10) and 3.6223 (10) Å] also occur.

Related literature

For the crystal structure of imidazolium picrate, see: Soriano-García et al. (1990 ▶). For the structures of picrates of some other imidazole derivatives, see, for example: Nardelli et al. (1987 ▶); Du & Zhao (2003 ▶); MacDonald et al. (2005 ▶); Pi et al. (2009 ▶).

Experimental

Crystal data

C₄H₇N₂ ⁺·C₆H₂N₃O₇ ⁻
M _r = 311.22
Monoclinic,
a = 7.0983 (9) Å
b = 21.644 (2) Å
c = 8.1583 (9) Å
β = 100.327 (12)°
V = 1233.1 (2) Å³
Z = 4
Mo Kα radiation
μ = 0.15 mm⁻¹
T = 295 K
0.3 × 0.2 × 0.2 mm

Data collection

Oxford Diffraction Xcalibur Eos diffractometer
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009 ▶) T _min = 0.964, T _max = 1.000
4778 measured reflections
2483 independent reflections
1792 reflections with I > 2σ(I)
R _int = 0.014

Refinement

R[F ² > 2σ(F ²)] = 0.039
wR(F ²) = 0.101
S = 1.03
2483 reflections
235 parameters
All H-atom parameters refined
Δρ_max = 0.30 e Å⁻³
Δρ_min = −0.27 e Å⁻³

Data collection: CrysAlis PRO (Oxford Diffraction, 2009 ▶); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SIR92 (Altomare et al., 1993 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: Stereochemical Workstation Operation Manual. (Siemens, 1989 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810053390/dn2638sup1.cif

e-67-0o235-sup1.cif^{(17.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810053390/dn2638Isup2.hkl

e-67-0o235-Isup2.hkl^{(119.5KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C5—H5⋯O21ⁱ	0.911 (19)	2.478 (19)	3.378 (2)	169.4 (16)
N11—H11⋯O1	0.89 (2)	1.95 (2)	2.8357 (19)	172.9 (19)
N13—H13⋯O1ⁱⁱ	0.86 (2)	2.09 (2)	2.819 (2)	143 (2)
N13—H13⋯O22ⁱⁱ	0.86 (2)	2.14 (2)	2.782 (2)	131.3 (19)

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Symmetry codes: (i) Inline graphic ; (ii) .

Acknowledgments

SS thanks Mangalore University for the research facilities

supplementary crystallographic information

Comment

The imidazole nucleus appears in a number of naturally occurring products like amino acid histidine and purines which comprise many of the most important bases in nucleic acids. Imidazole derivatives deal with a broad spectrum of pharmacological activities. The crystal structures of some imidazolium picrates have been reported, for instance imidazolium picrate itself (Soriano-García et al. (1990); also two solvates (hydrate and ethanolate) of 2-aminohistamine dipicrate (Nardelli et al.,1987), 4-hydroxymethylimidazolium picrate (Du & Zhao, 2003), two polymorphs of betaine bis(diimidazolium) dipicrate (MacDonald et al., 2005) and 3-benzyl-1-methyl-imidazolium picrate (Pi et al., 2009).

The title compound, 2-methylimidazolium picrate (2-methyl-1H-imidazol-3-ium 2,4,6-trinitrophenolate, Scheme 1) crystallizes with two ionic components, as proved by successful location and refinement of hydrogen atoms at both imiadzole nitrogen atoms as well as by the bond length pattern. Both cyclic fragments are in a good approximation planar. As might be expected, the deviations from the least-squares plane are by an order of magnitude smaller in the imidazolium ring (maximum 0.0028 (10) Å) than in a six-atom ring of picrate anion (0.0289 (10) Å). The two rings make a dihedral angle of 60.28 (7)°. The nitro groups are twisted with respect to the ring plane; the dihedral angles are larger for the substituents ortho- with respect to the C=O^- group (18.46 (12)° and 53.59 (9)°) than for the para-group, which is 7.28 (16)°.

The ionic fragments are conneced by relatively short N—H···O hydrogen bonds. One of N—H groups acts as a donor in almost linear hydrogen bond, while the other is involved in the bifurcated N—H···O bonds, in which O1 atom and one of nitro group O atoms act as acceptors. These two bonds are of similar lengths and therefore they deviate significantly from linearity. These hydrogen bonds, together with relatively short C—H···O contacts connect the cations and anions into a layer in which one can find the C¹₂(6) chains, created only by N—H···O hydrogen bonds and R⁴₅(21) rings, in which all contacts are involved (Fig. 2).

The layers related by centers of symmetry are additionally connected by quite short π–π stacking interactions between six-membered rings. The distances between the centers of consecutive rings in a stack are 3.594Å and 3.621Å, but if the parallel shift is taken into account the distances between the planes are 3.48Å and 3.27Å (Fig. 3). It should be noted, however, that the parallel shift is in these cases 1.00Å and 1.50Å, respectively, which might suggest weak π–π stacking in the first case but edge-to-edge kind of interaction in the second.

Experimental

2-Methyl imidazole (0.82 g, 0.01 mol) was dissolved in 25 ml of ethanol. Picric acid (2.29 g, 0.01 mol) was dissolved in 15 ml of water. Both the solutions were mixed and to this, 5 ml of 5M HCl was added and stirred for few minutes. The formed complex (I) was filtered and dried. Good quality crystals were grown from ethanol solution by slow evaporation (m. p.: 483 K). Composition: Found (Calculated): C: 38.50 (38.59); H: 2.88 (2.91); N: 22.45 (22.50).