organic compounds
2-Methylimidazolium picrate
aDepartment of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznań, Poland, bDepartment of Studies in Chemistry, Mangalore University, Mangalagangotri 574 199, India, and cDepartment of Studies in Chemistry, University of Mysore, Manasagangotri, Mysore 570 006, India
*Correspondence e-mail: mkubicki@amu.edu.pl
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 et al. (1990). For the structures of of some other imidazole derivatives, see, for example: Nardelli et al. (1987); Du & Zhao (2003); MacDonald et al. (2005); Pi et al. (2009).
of imidazolium picrate, see: Soriano-GarcíaExperimental
Crystal data
|
Refinement
|
Data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell 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.
Supporting information
https://doi.org/10.1107/S1600536810053390/dn2638sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810053390/dn2638Isup2.hkl
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).
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
Imidazole derivatives deal with a broad spectrum of pharmacological activities. The crystal structures of some imidazolium 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
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.
For the
of imidazolium picrate, see: Soriano-García et al. (1990). For the structures of of some other imidazole derivatives, see, for example: Nardelli et al. (1987); Du & Zhao (2003); MacDonald et al. (2005);Pi et al. (2009).Data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell
CrysAlis PRO (Oxford Diffraction, 2009); data reduction: CrysAlis PRO (Oxford Diffraction, 2009); 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 (Sheldrick, 2008).C4H7N2+·C6H2N3O7− | F(000) = 640 |
Mr = 311.22 | Dx = 1.676 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 2592 reflections |
a = 7.0983 (9) Å | θ = 2.9–28.2° |
b = 21.644 (2) Å | µ = 0.15 mm−1 |
c = 8.1583 (9) Å | T = 295 K |
β = 100.327 (12)° | Block, yellow |
V = 1233.1 (2) Å3 | 0.3 × 0.2 × 0.2 mm |
Z = 4 |
Oxford Diffraction Xcalibur Eos diffractometer | 2483 independent reflections |
Radiation source: Enhance (Mo) X-ray Source | 1792 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.014 |
Detector resolution: 16.1544 pixels mm-1 | θmax = 28.2°, θmin = 2.9° |
ω scans | h = −8→9 |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) | k = −15→28 |
Tmin = 0.964, Tmax = 1.000 | l = −10→10 |
4778 measured reflections |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.039 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.101 | All H-atom parameters refined |
S = 1.03 | w = 1/[σ2(Fo2) + (0.060P)2] where P = (Fo2 + 2Fc2)/3 |
2483 reflections | (Δ/σ)max = 0.001 |
235 parameters | Δρmax = 0.30 e Å−3 |
0 restraints | Δρmin = −0.27 e Å−3 |
C4H7N2+·C6H2N3O7− | V = 1233.1 (2) Å3 |
Mr = 311.22 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 7.0983 (9) Å | µ = 0.15 mm−1 |
b = 21.644 (2) Å | T = 295 K |
c = 8.1583 (9) Å | 0.3 × 0.2 × 0.2 mm |
β = 100.327 (12)° |
Oxford Diffraction Xcalibur Eos diffractometer | 2483 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) | 1792 reflections with I > 2σ(I) |
Tmin = 0.964, Tmax = 1.000 | Rint = 0.014 |
4778 measured reflections |
R[F2 > 2σ(F2)] = 0.039 | 0 restraints |
wR(F2) = 0.101 | All H-atom parameters refined |
S = 1.03 | Δρmax = 0.30 e Å−3 |
2483 reflections | Δρmin = −0.27 e Å−3 |
235 parameters |
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
C1 | 0.3265 (2) | 0.93118 (8) | 0.60988 (19) | 0.0241 (4) | |
O1 | 0.38378 (17) | 0.88003 (5) | 0.67241 (14) | 0.0347 (3) | |
C2 | 0.2787 (2) | 0.98440 (7) | 0.70037 (19) | 0.0253 (4) | |
N2 | 0.2874 (2) | 0.98159 (7) | 0.88019 (17) | 0.0358 (4) | |
O21 | 0.2016 (3) | 1.02077 (8) | 0.94412 (17) | 0.0716 (5) | |
O22 | 0.3770 (3) | 0.94120 (7) | 0.96128 (17) | 0.0656 (5) | |
C3 | 0.2171 (2) | 1.03981 (8) | 0.6272 (2) | 0.0266 (4) | |
H3 | 0.189 (2) | 1.0723 (8) | 0.691 (2) | 0.028 (5)* | |
C4 | 0.1956 (2) | 1.04630 (8) | 0.4569 (2) | 0.0267 (4) | |
N4 | 0.1304 (2) | 1.10493 (7) | 0.38329 (19) | 0.0348 (4) | |
O41 | 0.1247 (2) | 1.11171 (7) | 0.23347 (17) | 0.0615 (5) | |
O42 | 0.08086 (19) | 1.14506 (6) | 0.47167 (17) | 0.0479 (4) | |
C5 | 0.2260 (2) | 0.99677 (8) | 0.3565 (2) | 0.0272 (4) | |
H5 | 0.205 (3) | 0.9999 (9) | 0.243 (2) | 0.041 (5)* | |
C6 | 0.2876 (2) | 0.94228 (7) | 0.43176 (19) | 0.0248 (4) | |
N6 | 0.3054 (2) | 0.89003 (7) | 0.32303 (17) | 0.0310 (3) | |
O61 | 0.45451 (19) | 0.86075 (6) | 0.34477 (16) | 0.0436 (4) | |
O62 | 0.1676 (2) | 0.87781 (7) | 0.21488 (17) | 0.0537 (4) | |
N11 | 0.5304 (2) | 0.76346 (7) | 0.59823 (18) | 0.0353 (4) | |
H11 | 0.491 (3) | 0.8016 (10) | 0.617 (3) | 0.054 (6)* | |
C12 | 0.4264 (2) | 0.72364 (8) | 0.49579 (19) | 0.0310 (4) | |
C12A | 0.2238 (3) | 0.73045 (13) | 0.4178 (3) | 0.0484 (5) | |
H12A | 0.163 (5) | 0.6936 (15) | 0.401 (4) | 0.129 (13)* | |
H12B | 0.155 (4) | 0.7574 (13) | 0.480 (3) | 0.094 (9)* | |
H12C | 0.213 (4) | 0.7461 (14) | 0.318 (4) | 0.111 (11)* | |
N13 | 0.5382 (2) | 0.67629 (7) | 0.47868 (18) | 0.0341 (4) | |
H13 | 0.506 (3) | 0.6450 (11) | 0.416 (3) | 0.056 (7)* | |
C14 | 0.7165 (3) | 0.68530 (9) | 0.5723 (2) | 0.0377 (4) | |
H14 | 0.811 (3) | 0.6565 (10) | 0.574 (2) | 0.046 (6)* | |
C15 | 0.7118 (3) | 0.74005 (9) | 0.6470 (2) | 0.0391 (5) | |
H15 | 0.808 (3) | 0.7634 (10) | 0.719 (3) | 0.057 (6)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0225 (7) | 0.0236 (9) | 0.0259 (8) | 0.0002 (7) | 0.0035 (6) | 0.0003 (7) |
O1 | 0.0505 (7) | 0.0247 (7) | 0.0282 (6) | 0.0088 (6) | 0.0053 (5) | 0.0019 (5) |
C2 | 0.0274 (8) | 0.0263 (9) | 0.0219 (8) | −0.0003 (7) | 0.0038 (6) | 0.0000 (7) |
N2 | 0.0501 (9) | 0.0318 (9) | 0.0252 (7) | 0.0080 (7) | 0.0062 (7) | −0.0004 (7) |
O21 | 0.1138 (13) | 0.0717 (12) | 0.0334 (7) | 0.0473 (10) | 0.0244 (8) | 0.0002 (8) |
O22 | 0.1215 (14) | 0.0427 (9) | 0.0296 (7) | 0.0315 (9) | 0.0057 (8) | 0.0062 (7) |
C3 | 0.0266 (8) | 0.0239 (9) | 0.0299 (9) | 0.0008 (7) | 0.0070 (7) | −0.0040 (8) |
C4 | 0.0280 (8) | 0.0209 (9) | 0.0321 (9) | 0.0018 (7) | 0.0077 (7) | 0.0050 (7) |
N4 | 0.0378 (8) | 0.0286 (9) | 0.0385 (8) | 0.0024 (7) | 0.0084 (7) | 0.0083 (7) |
O41 | 0.1011 (12) | 0.0457 (9) | 0.0393 (8) | 0.0197 (8) | 0.0173 (8) | 0.0183 (7) |
O42 | 0.0632 (9) | 0.0264 (7) | 0.0563 (9) | 0.0118 (6) | 0.0165 (7) | 0.0024 (7) |
C5 | 0.0292 (8) | 0.0304 (10) | 0.0223 (8) | −0.0002 (7) | 0.0052 (7) | 0.0037 (8) |
C6 | 0.0261 (8) | 0.0239 (9) | 0.0250 (8) | −0.0007 (7) | 0.0067 (6) | −0.0028 (7) |
N6 | 0.0395 (8) | 0.0282 (8) | 0.0265 (7) | −0.0004 (7) | 0.0093 (6) | −0.0008 (6) |
O61 | 0.0498 (8) | 0.0378 (8) | 0.0451 (8) | 0.0136 (7) | 0.0134 (6) | −0.0063 (6) |
O62 | 0.0563 (8) | 0.0575 (10) | 0.0419 (8) | −0.0018 (7) | −0.0060 (7) | −0.0211 (7) |
N11 | 0.0479 (9) | 0.0240 (8) | 0.0329 (8) | −0.0010 (8) | 0.0044 (7) | −0.0042 (7) |
C12 | 0.0424 (10) | 0.0252 (9) | 0.0256 (8) | −0.0034 (8) | 0.0067 (7) | −0.0002 (7) |
C12A | 0.0426 (12) | 0.0519 (15) | 0.0477 (12) | −0.0025 (11) | 0.0000 (10) | 0.0012 (12) |
N13 | 0.0501 (9) | 0.0230 (8) | 0.0293 (8) | −0.0043 (7) | 0.0077 (7) | −0.0044 (7) |
C14 | 0.0426 (11) | 0.0329 (11) | 0.0381 (10) | 0.0036 (9) | 0.0084 (9) | 0.0046 (9) |
C15 | 0.0416 (10) | 0.0374 (12) | 0.0356 (10) | −0.0071 (9) | −0.0005 (8) | 0.0006 (9) |
C1—O1 | 1.2557 (19) | N6—O61 | 1.2193 (18) |
C1—C2 | 1.441 (2) | N6—O62 | 1.2226 (19) |
C1—C6 | 1.450 (2) | N11—C12 | 1.329 (2) |
C2—C3 | 1.376 (2) | N11—C15 | 1.375 (2) |
C2—N2 | 1.459 (2) | N11—H11 | 0.89 (2) |
N2—O22 | 1.2067 (19) | C12—N13 | 1.319 (2) |
N2—O21 | 1.2145 (19) | C12—C12A | 1.472 (3) |
C3—C4 | 1.377 (2) | C12A—H12A | 0.91 (3) |
C3—H3 | 0.918 (18) | C12A—H12B | 0.96 (3) |
C4—C5 | 1.389 (2) | C12A—H12C | 0.87 (3) |
C4—N4 | 1.444 (2) | N13—C14 | 1.370 (2) |
N4—O42 | 1.2200 (19) | N13—H13 | 0.86 (2) |
N4—O41 | 1.2245 (19) | C14—C15 | 1.336 (3) |
C5—C6 | 1.365 (2) | C14—H14 | 0.92 (2) |
C5—H5 | 0.911 (19) | C15—H15 | 0.96 (2) |
C6—N6 | 1.457 (2) | ||
O1—C1—C2 | 125.83 (14) | O61—N6—O62 | 123.62 (15) |
O1—C1—C6 | 122.88 (14) | O61—N6—C6 | 118.85 (14) |
C2—C1—C6 | 111.17 (14) | O62—N6—C6 | 117.53 (14) |
C3—C2—C1 | 124.06 (14) | C12—N11—C15 | 109.23 (16) |
C3—C2—N2 | 115.19 (14) | C12—N11—H11 | 123.3 (13) |
C1—C2—N2 | 120.72 (14) | C15—N11—H11 | 126.7 (13) |
O22—N2—O21 | 121.74 (15) | N13—C12—N11 | 107.04 (16) |
O22—N2—C2 | 120.29 (14) | N13—C12—C12A | 126.31 (18) |
O21—N2—C2 | 117.97 (15) | N11—C12—C12A | 126.64 (18) |
C2—C3—C4 | 119.73 (16) | C12—C12A—H12A | 112 (2) |
C2—C3—H3 | 120.5 (11) | C12—C12A—H12B | 112.4 (16) |
C4—C3—H3 | 119.7 (11) | H12A—C12A—H12B | 110 (2) |
C3—C4—C5 | 121.00 (15) | C12—C12A—H12C | 111 (2) |
C3—C4—N4 | 118.57 (15) | H12A—C12A—H12C | 104 (3) |
C5—C4—N4 | 120.34 (15) | H12B—C12A—H12C | 107 (3) |
O42—N4—O41 | 122.90 (16) | C12—N13—C14 | 110.12 (16) |
O42—N4—C4 | 118.99 (15) | C12—N13—H13 | 125.4 (15) |
O41—N4—C4 | 118.10 (15) | C14—N13—H13 | 124.5 (15) |
C6—C5—C4 | 118.21 (15) | C15—C14—N13 | 106.55 (17) |
C6—C5—H5 | 120.2 (12) | C15—C14—H14 | 132.4 (13) |
C4—C5—H5 | 121.6 (12) | N13—C14—H14 | 121.0 (13) |
C5—C6—C1 | 125.60 (15) | C14—C15—N11 | 107.06 (17) |
C5—C6—N6 | 116.91 (14) | C14—C15—H15 | 132.4 (13) |
C1—C6—N6 | 117.40 (14) | N11—C15—H15 | 120.5 (13) |
O1—C1—C2—C3 | 179.72 (16) | C4—C5—C6—C1 | −0.5 (2) |
C6—C1—C2—C3 | −4.2 (2) | C4—C5—C6—N6 | 175.84 (13) |
O1—C1—C2—N2 | −2.4 (2) | O1—C1—C6—C5 | −179.73 (16) |
C6—C1—C2—N2 | 173.62 (14) | C2—C1—C6—C5 | 4.1 (2) |
C3—C2—N2—O22 | −163.80 (17) | O1—C1—C6—N6 | 3.9 (2) |
C1—C2—N2—O22 | 18.2 (2) | C2—C1—C6—N6 | −172.26 (13) |
C3—C2—N2—O21 | 16.4 (2) | C5—C6—N6—O61 | 129.43 (16) |
C1—C2—N2—O21 | −161.61 (17) | C1—C6—N6—O61 | −53.90 (19) |
C1—C2—C3—C4 | 0.9 (2) | C5—C6—N6—O62 | −51.0 (2) |
N2—C2—C3—C4 | −177.07 (14) | C1—C6—N6—O62 | 125.64 (17) |
C2—C3—C4—C5 | 3.3 (2) | C15—N11—C12—N13 | −0.36 (19) |
C2—C3—C4—N4 | 179.90 (14) | C15—N11—C12—C12A | 178.83 (19) |
C3—C4—N4—O42 | −6.2 (2) | N11—C12—N13—C14 | 0.53 (19) |
C5—C4—N4—O42 | 170.49 (15) | C12A—C12—N13—C14 | −178.67 (18) |
C3—C4—N4—O41 | 174.92 (16) | C12—N13—C14—C15 | −0.49 (19) |
C5—C4—N4—O41 | −8.4 (2) | N13—C14—C15—N11 | 0.25 (19) |
C3—C4—C5—C6 | −3.4 (2) | C12—N11—C15—C14 | 0.1 (2) |
N4—C4—C5—C6 | −179.99 (15) |
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) |
Symmetry codes: (i) x, y, z−1; (ii) x, −y+3/2, z−1/2. |
Experimental details
Crystal data | |
Chemical formula | C4H7N2+·C6H2N3O7− |
Mr | 311.22 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 295 |
a, b, c (Å) | 7.0983 (9), 21.644 (2), 8.1583 (9) |
β (°) | 100.327 (12) |
V (Å3) | 1233.1 (2) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.15 |
Crystal size (mm) | 0.3 × 0.2 × 0.2 |
Data collection | |
Diffractometer | Oxford Diffraction Xcalibur Eos |
Absorption correction | Multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) |
Tmin, Tmax | 0.964, 1.000 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4778, 2483, 1792 |
Rint | 0.014 |
(sin θ/λ)max (Å−1) | 0.665 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.039, 0.101, 1.03 |
No. of reflections | 2483 |
No. of parameters | 235 |
H-atom treatment | All H-atom parameters refined |
Δρmax, Δρmin (e Å−3) | 0.30, −0.27 |
Computer programs: CrysAlis PRO (Oxford Diffraction, 2009), SIR92 (Altomare et al., 1993), SHELXL97 (Sheldrick, 2008), Stereochemical Workstation Operation Manual. (Siemens, 1989).
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) |
Symmetry codes: (i) x, y, z−1; (ii) x, −y+3/2, z−1/2. |
Acknowledgements
SS thanks Mangalore University for the research facilities
References
Altomare, A., Cascarano, G., Giacovazzo, C. & Guagliardi, A. (1993). J. Appl. Cryst. 26, 343–350. CrossRef Web of Science IUCr Journals Google Scholar
Du, M. & Zhao, X.-J. (2003). Acta Cryst. E59, o1898–o1900. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
MacDonald, J., Yigit, M. V. & Mychajlonka, K. (2005). Cryst. Growth Des. 5, 2248–2255. Web of Science CSD CrossRef CAS Google Scholar
Nardelli, M., Pelizzi, G., Vitali, F., Bordi, F., Plazzi, P. V. & Vitali, T. (1987). Acta Cryst. C43, 507–514. CSD CrossRef CAS Web of Science IUCr Journals Google Scholar
Oxford Diffraction (2009). CrysAlis PRO. Oxford Diffraction Ltd, Yarnton, Oxfordshire, England. Google Scholar
Pi, M., Liu, X.-L., Xu, J.-J. & Jin, C.-M. (2009). Acta Cryst. E65, o2386. Web of Science CSD CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Siemens (1989). Stereochemical Workstation Operation Manual. Siemens Analytical X-ray Instruments Inc., Madison, Wisconsin, USA. Google Scholar
Soriano-García, M., Schatz-Levine, M., Toscano, R. A. & Villena Iribe, R. (1990). Acta Cryst. C46, 1556–1558. CSD CrossRef Web of Science IUCr Journals Google Scholar
This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
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.