research communications
Hydrogen bonding in the
of the molecular salt of pyrazole–pyrazolium picrateaCollege of Chemistry, Central China Normal University, Wuhan 430079, People's Republic of China
*Correspondence e-mail: xingman_xu@126.com
The H-pyrazol-2-ium 2,4,6-trinitrophenolate–1H-pyrazole (1/1)], H(C3H4N2)2+·C6H2N3O7−, consists of one picrate anion and one hydrogen-bonded dimer of a pyrazolium monocation. The H atom involved in the dimer N—H⋯N hydrogen bond is disordered over both symmetry-unique pyrazole molecules with occupancies of 0.52 (5) and 0.48 (5). In the crystal, the component ions are linked into chains along [100] by two different bifurcated N—H⋯(O,O) hydrogen bonds. In addition, weak C—H⋯O hydrogen bonds link inversion-related chains, forming columns along [100].
of the title organic salt [systematic name: 1Keywords: crystal structure; organic salt; pyrazole; picric acid; hydrogen bonding.
CCDC reference: 1480969
1. Chemical context
Research interest on co-crystals or organic complex salts in recent years has been prompted by their potential utilization in the pharmaceutical industry (Blagden et al., 2014; Duggirala et al., 2016). Imidazole and pyrazole derivatives are often used as co-crystallized pharmaceutical ingredients (Shimpi et al., 2014). Our investigations involve studies of weak intermolecular interactions in co-crystallized compounds. As part of our continuing study on organic salts formed by imidazole derivatives and picric acid (Song et al., 2016; Su et al., 2008), we report herein the of the title compound (I).
2. Structural commentary
The . It consists of one picrate anion and two pyrazole molecules, which are connected by an N—H⋯N hydrogen bond (Table 1), forming a dimeric pyrazolium monocation. The H atom of the hydrogen bond is disordered over both pyrazole molecules. In the dimeric monocation, the two pyrazole rings form a dihedral angle of 74.6 (1)°. In the anion, the C—Ophenol bond [1.257 (3)Å] is shorter by ca 0.05Å than an average C—O single bond in a neutral picric acid molecule [1.308 (2)Å] calculated statistically by analysis of a CSD search (Groom et al., 2016; Allen, 2002). The C1—C2 [1.438 (4)Å] and C1—C6 [1.449 (4)Å] bonds are significantly longer than the other four benzene C-C bonds [1.367 (4)–1.380 (4)Å]. The C2—C1—C6 [111.9 (2)°] angle is smaller than the ideal value of 120° for a regular hexagon and the other five benzene inner angles of 119.0 (3)–124.4 (3). All variations of bond lengths and angles demonstrate that the negative charge on the phenol oxygen atom is delocalized over the aromatic ring, giving double-bond character for the C1—O1 bond due to the electron-withdrawing effect of the three nitro groups. This is similar to what is observed in some picrate-containing analogs (Zakharov et al., 2015; Gomathi & Kalaivani, 2015). The mean planes of the nitro groups in the anion, are twisted from the benzene ring by dihedral angles of 30.8 (2), 4.8 (3)° and 27.2 (4)° for N1/O2/O3, N2/O4/O5 and N3/O6/O7, respectively. The two ortho-nitro groups are twisted out of the benzene ring to a greater extent than the para-nitro group. This is most likely due to the between the ortho-nitro groups and the phenolic oxygen atom.
of the title compound is shown in Fig. 13. Supramolecular features
In the crystal of (I), the component ions are linked into a chain along [100] by N—H⋯O hydrogen bonds (Table 1, Fig. 2). In addition, inversion-related chains are connected by a weak C12—H12⋯O4 (−x, −y + 2, −z + 1) hydrogen bond, forming columns along [100]. A short O3(nitro)⋯O3(nitro) (−1 − x, 2 − y, 1 − z) distance of 2.913 (2) Å is also observed (Spek, 2009). Although the benzene and pyrazolium rings are stacked in a parallel fashion, no significant π–π interactions exist between them (Janiak, 2000). This could be attributed to the deficient π-electron nature resulting from the electron-withdrawing effects of the nitro groups.
4. Database survey
A search of the Cambridge Structural Database (CSD Version 5.37 plus one update; Groom et al., 2016) indicates there are some analogs prepared from picric acid and pyrazole derivatives, viz. SASKII, SASLAB, SASKUU, SASLUB (Singh et al., 2012) and SASKII01 (Dhanabal et al., 2013). A similar solvated organic adduct, C5H9N2+·C6H2N3O7− (SASKII; Singh et al., 2012) indicates that the solvent used for the crystallization process can affect the final product in which the ratio of component ions are different.
5. Synthesis and crystallization
Pyrazole (20.0 mmol, 136.0 mg) and picric acid (10. 0 mmol, 230.0mg) were dissolved in a 2:1 molar ratio in 95% methanol (50.0 ml). The mixture was stirred for an hour at 323 K and then cooled to room temperature and filtered. The resulting yellow solution was kept in air for two weeks. Needle-like yellow crystals of (I) suitable for single-crystal X-ray were grown by slow evaporation of the solution. The crystals were separated by filtration (yield, 60%, ca 0.22 g).
6. Refinement
Crystal data, data collection and structure . H atoms bonded to C atoms were positioned geometrically with C—H = 0.93 Å (aromatic) and refined in a riding-model approximation with Uiso(H) = 1.2Ueq(C). H atoms bonded to N atoms were refined with a constraint of dN—H = 0.86 (1) Å and Uiso(H) = 1.2Ueq(N). Atoms H4A and H6A were found in difference Fourier maps and refined as disordered using the PART command (Sheldrick, 2015). The final site occupancies of the two hydrogen-atom components were 0.52 (1):0.48 (1) for H6A and H4A, respectively.
details are summarized in Table 2
|
Supporting information
CCDC reference: 1480969
https://doi.org/10.1107/S2056989016008215/lh5810sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989016008215/lh5810Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2056989016008215/lh5810Isup3.cml
Data collection: SMART (Bruker, 2001); cell
SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: SHELXTL (Sheldrick, 2008) and DIAMOND (Brandenburg, 2006); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).C3H5N2+·C6H2N3O7−·C3H4N2 | F(000) = 752 |
Mr = 365.28 | Dx = 1.545 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 4.2447 (14) Å | Cell parameters from 1735 reflections |
b = 16.950 (5) Å | θ = 2.4–20.5° |
c = 21.839 (7) Å | µ = 0.13 mm−1 |
β = 92.029 (6)° | T = 298 K |
V = 1570.3 (9) Å3 | Needle, yellow |
Z = 4 | 0.45 × 0.06 × 0.04 mm |
Bruker SMART CCD diffractometer | 1787 reflections with I > 2σ(I) |
φ and ω scans | Rint = 0.050 |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | θmax = 26.0°, θmin = 1.5° |
Tmin = 0.736, Tmax = 0.875 | h = −5→5 |
12038 measured reflections | k = −20→20 |
3086 independent reflections | l = −26→24 |
Refinement on F2 | 4 restraints |
Least-squares matrix: full | H atoms treated by a mixture of independent and constrained refinement |
R[F2 > 2σ(F2)] = 0.057 | w = 1/[σ2(Fo2) + (0.0698P)2 + 0.3803P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.157 | (Δ/σ)max < 0.001 |
S = 0.98 | Δρmax = 0.18 e Å−3 |
3086 reflections | Δρmin = −0.16 e Å−3 |
248 parameters |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
C1 | 0.2577 (7) | 0.78567 (15) | 0.50270 (13) | 0.0502 (7) | |
C2 | 0.0904 (7) | 0.85715 (15) | 0.51570 (12) | 0.0478 (7) | |
C3 | 0.0496 (7) | 0.88621 (16) | 0.57336 (13) | 0.0565 (8) | |
H3 | −0.0667 | 0.9320 | 0.5789 | 0.068* | |
C4 | 0.1825 (8) | 0.84691 (17) | 0.62309 (13) | 0.0577 (8) | |
C5 | 0.3503 (7) | 0.77808 (17) | 0.61557 (13) | 0.0573 (8) | |
H5 | 0.4423 | 0.7525 | 0.6494 | 0.069* | |
C6 | 0.3802 (7) | 0.74780 (15) | 0.55807 (13) | 0.0506 (7) | |
C7 | 0.7321 (8) | 0.56590 (19) | 0.33757 (15) | 0.0683 (9) | |
H7 | 0.5902 | 0.5601 | 0.3045 | 0.082* | |
C8 | 0.8600 (8) | 0.50504 (18) | 0.37140 (16) | 0.0689 (9) | |
H8 | 0.8229 | 0.4514 | 0.3660 | 0.083* | |
C9 | 1.0517 (8) | 0.53966 (19) | 0.41426 (15) | 0.0679 (9) | |
H9 | 1.1731 | 0.5137 | 0.4443 | 0.082* | |
C10 | 0.8031 (8) | 0.80992 (19) | 0.26399 (14) | 0.0675 (9) | |
H10 | 0.9374 | 0.7862 | 0.2367 | 0.081* | |
C11 | 0.6789 (9) | 0.88402 (19) | 0.25746 (15) | 0.0698 (9) | |
H11 | 0.7114 | 0.9197 | 0.2260 | 0.084* | |
C12 | 0.4981 (8) | 0.89415 (18) | 0.30687 (15) | 0.0648 (9) | |
H12 | 0.3809 | 0.9388 | 0.3157 | 0.078* | |
N1 | −0.0457 (6) | 0.90430 (13) | 0.46540 (12) | 0.0532 (6) | |
N2 | 0.1422 (9) | 0.87879 (19) | 0.68408 (13) | 0.0815 (9) | |
N3 | 0.5497 (7) | 0.67352 (16) | 0.55396 (14) | 0.0645 (7) | |
N4 | 0.8395 (7) | 0.63381 (15) | 0.35881 (12) | 0.0613 (7) | |
H4A | 0.808 (16) | 0.6815 (15) | 0.346 (3) | 0.074* | 0.48 (5) |
N5 | 1.0360 (7) | 0.61758 (14) | 0.40591 (12) | 0.0617 (7) | |
H5A | 1.133 (7) | 0.6554 (14) | 0.4254 (13) | 0.074* | |
N6 | 0.7043 (7) | 0.77681 (14) | 0.31469 (12) | 0.0600 (7) | |
H6A | 0.761 (15) | 0.7321 (19) | 0.330 (3) | 0.072* | 0.52 (5) |
N7 | 0.5183 (6) | 0.82915 (14) | 0.34019 (11) | 0.0553 (6) | |
H7A | 0.434 (7) | 0.8196 (18) | 0.3747 (8) | 0.066* | |
O1 | 0.2919 (6) | 0.75921 (11) | 0.44959 (9) | 0.0668 (6) | |
O2 | 0.0820 (5) | 0.90477 (13) | 0.41655 (9) | 0.0709 (7) | |
O3 | −0.2780 (5) | 0.94352 (13) | 0.47569 (11) | 0.0756 (7) | |
O4 | −0.0220 (9) | 0.93651 (17) | 0.68985 (11) | 0.1281 (13) | |
O5 | 0.2766 (8) | 0.84518 (17) | 0.72727 (12) | 0.1047 (10) | |
O6 | 0.4897 (7) | 0.62868 (15) | 0.51168 (12) | 0.0976 (9) | |
O7 | 0.7405 (7) | 0.65737 (15) | 0.59511 (13) | 0.0968 (9) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0571 (19) | 0.0411 (15) | 0.0529 (18) | −0.0044 (13) | 0.0093 (14) | 0.0021 (13) |
C2 | 0.0536 (18) | 0.0405 (14) | 0.0496 (17) | −0.0054 (13) | 0.0070 (14) | 0.0018 (12) |
C3 | 0.069 (2) | 0.0407 (15) | 0.0609 (19) | −0.0060 (14) | 0.0160 (16) | 0.0012 (14) |
C4 | 0.083 (2) | 0.0481 (17) | 0.0431 (17) | −0.0152 (16) | 0.0113 (16) | −0.0028 (13) |
C5 | 0.067 (2) | 0.0531 (17) | 0.0517 (18) | −0.0163 (15) | 0.0001 (15) | 0.0063 (14) |
C6 | 0.0516 (18) | 0.0417 (15) | 0.0586 (19) | −0.0056 (13) | 0.0047 (14) | 0.0059 (13) |
C7 | 0.081 (2) | 0.0542 (19) | 0.070 (2) | 0.0002 (17) | 0.0032 (18) | 0.0008 (16) |
C8 | 0.082 (2) | 0.0443 (17) | 0.081 (2) | 0.0001 (17) | 0.011 (2) | 0.0028 (17) |
C9 | 0.079 (2) | 0.0543 (19) | 0.072 (2) | 0.0136 (17) | 0.0130 (19) | 0.0148 (16) |
C10 | 0.082 (2) | 0.064 (2) | 0.057 (2) | 0.0059 (18) | 0.0108 (17) | −0.0026 (16) |
C11 | 0.084 (2) | 0.062 (2) | 0.064 (2) | 0.0043 (18) | 0.0063 (18) | 0.0165 (16) |
C12 | 0.071 (2) | 0.0494 (17) | 0.074 (2) | 0.0102 (15) | 0.0029 (18) | 0.0093 (16) |
N1 | 0.0543 (16) | 0.0428 (13) | 0.0625 (17) | −0.0019 (12) | 0.0015 (13) | −0.0003 (12) |
N2 | 0.136 (3) | 0.0584 (18) | 0.0513 (18) | −0.0198 (18) | 0.0169 (18) | −0.0022 (15) |
N3 | 0.0695 (19) | 0.0586 (16) | 0.0659 (18) | 0.0079 (14) | 0.0087 (15) | 0.0137 (15) |
N4 | 0.080 (2) | 0.0445 (15) | 0.0593 (17) | 0.0116 (14) | 0.0079 (15) | 0.0077 (13) |
N5 | 0.075 (2) | 0.0482 (16) | 0.0624 (18) | 0.0046 (13) | 0.0103 (15) | −0.0023 (13) |
N6 | 0.0765 (19) | 0.0439 (14) | 0.0593 (17) | 0.0071 (13) | −0.0008 (14) | 0.0020 (13) |
N7 | 0.0655 (17) | 0.0490 (14) | 0.0513 (15) | 0.0082 (12) | 0.0033 (12) | 0.0009 (12) |
O1 | 0.1065 (18) | 0.0453 (11) | 0.0493 (13) | 0.0069 (11) | 0.0120 (12) | 0.0007 (9) |
O2 | 0.0857 (17) | 0.0755 (15) | 0.0519 (14) | 0.0201 (12) | 0.0063 (12) | 0.0082 (11) |
O3 | 0.0627 (15) | 0.0675 (14) | 0.0969 (18) | 0.0187 (12) | 0.0090 (13) | 0.0079 (12) |
O4 | 0.244 (4) | 0.0713 (18) | 0.0722 (18) | 0.027 (2) | 0.046 (2) | −0.0084 (14) |
O5 | 0.153 (3) | 0.106 (2) | 0.0549 (16) | −0.0167 (19) | −0.0024 (17) | −0.0058 (14) |
O6 | 0.148 (3) | 0.0690 (15) | 0.0753 (17) | 0.0389 (16) | 0.0009 (16) | −0.0061 (14) |
O7 | 0.095 (2) | 0.0828 (18) | 0.111 (2) | 0.0201 (15) | −0.0245 (17) | 0.0184 (15) |
C1—O1 | 1.257 (3) | C10—N6 | 1.323 (4) |
C1—C2 | 1.438 (4) | C10—C11 | 1.368 (4) |
C1—C6 | 1.449 (4) | C10—H10 | 0.9300 |
C2—C3 | 1.369 (4) | C11—C12 | 1.357 (4) |
C2—N1 | 1.461 (4) | C11—H11 | 0.9300 |
C3—C4 | 1.378 (4) | C12—N7 | 1.321 (4) |
C3—H3 | 0.9300 | C12—H12 | 0.9300 |
C4—C5 | 1.380 (4) | N1—O2 | 1.214 (3) |
C4—N2 | 1.453 (4) | N1—O3 | 1.216 (3) |
C5—C6 | 1.367 (4) | N2—O4 | 1.210 (4) |
C5—H5 | 0.9300 | N2—O5 | 1.225 (4) |
C6—N3 | 1.454 (4) | N3—O6 | 1.216 (3) |
C7—N4 | 1.316 (4) | N3—O7 | 1.219 (3) |
C7—C8 | 1.370 (4) | N4—N5 | 1.330 (4) |
C7—H7 | 0.9300 | N4—H4A | 0.862 (10) |
C8—C9 | 1.352 (5) | N5—H5A | 0.865 (10) |
C8—H8 | 0.9300 | N6—N7 | 1.323 (3) |
C9—N5 | 1.335 (4) | N6—H6A | 0.861 (10) |
C9—H9 | 0.9300 | N7—H7A | 0.861 (10) |
O1—C1—C2 | 123.9 (3) | C11—C10—H10 | 124.9 |
O1—C1—C6 | 124.2 (3) | C12—C11—C10 | 105.1 (3) |
C2—C1—C6 | 111.9 (2) | C12—C11—H11 | 127.5 |
C3—C2—C1 | 124.4 (3) | C10—C11—H11 | 127.5 |
C3—C2—N1 | 115.8 (2) | N7—C12—C11 | 107.7 (3) |
C1—C2—N1 | 119.8 (2) | N7—C12—H12 | 126.1 |
C2—C3—C4 | 119.3 (3) | C11—C12—H12 | 126.1 |
C2—C3—H3 | 120.3 | O2—N1—O3 | 123.3 (3) |
C4—C3—H3 | 120.3 | O2—N1—C2 | 119.2 (2) |
C3—C4—C5 | 120.9 (3) | O3—N1—C2 | 117.5 (3) |
C3—C4—N2 | 119.0 (3) | O4—N2—O5 | 123.3 (3) |
C5—C4—N2 | 120.1 (3) | O4—N2—C4 | 118.9 (3) |
C6—C5—C4 | 119.5 (3) | O5—N2—C4 | 117.8 (3) |
C6—C5—H5 | 120.3 | O6—N3—O7 | 122.3 (3) |
C4—C5—H5 | 120.3 | O6—N3—C6 | 119.8 (3) |
C5—C6—C1 | 123.9 (3) | O7—N3—C6 | 117.8 (3) |
C5—C6—N3 | 116.4 (3) | C7—N4—N5 | 106.9 (3) |
C1—C6—N3 | 119.7 (3) | C7—N4—H4A | 131 (5) |
N4—C7—C8 | 110.1 (3) | N5—N4—H4A | 122 (5) |
N4—C7—H7 | 125.0 | N4—N5—C9 | 109.7 (3) |
C8—C7—H7 | 125.0 | N4—N5—H5A | 120 (2) |
C9—C8—C7 | 105.3 (3) | C9—N5—H5A | 130 (2) |
C9—C8—H8 | 127.3 | C10—N6—N7 | 106.2 (2) |
C7—C8—H8 | 127.3 | C10—N6—H6A | 127 (4) |
N5—C9—C8 | 108.0 (3) | N7—N6—H6A | 126 (4) |
N5—C9—H9 | 126.0 | C12—N7—N6 | 110.8 (3) |
C8—C9—H9 | 126.0 | C12—N7—H7A | 128 (2) |
N6—C10—C11 | 110.2 (3) | N6—N7—H7A | 121 (2) |
N6—C10—H10 | 124.9 | ||
O1—C1—C2—C3 | 179.5 (3) | C10—C11—C12—N7 | 0.2 (4) |
C6—C1—C2—C3 | −0.3 (4) | C3—C2—N1—O2 | 148.3 (3) |
O1—C1—C2—N1 | −1.3 (4) | C1—C2—N1—O2 | −31.0 (4) |
C6—C1—C2—N1 | 179.0 (2) | C3—C2—N1—O3 | −29.2 (4) |
C1—C2—C3—C4 | 2.0 (4) | C1—C2—N1—O3 | 151.5 (3) |
N1—C2—C3—C4 | −177.3 (2) | C3—C4—N2—O4 | 4.1 (5) |
C2—C3—C4—C5 | −1.3 (4) | C5—C4—N2—O4 | −175.5 (3) |
C2—C3—C4—N2 | 179.1 (3) | C3—C4—N2—O5 | −176.2 (3) |
C3—C4—C5—C6 | −1.1 (4) | C5—C4—N2—O5 | 4.2 (5) |
N2—C4—C5—C6 | 178.5 (3) | C5—C6—N3—O6 | 152.3 (3) |
C4—C5—C6—C1 | 3.1 (4) | C1—C6—N3—O6 | −28.5 (4) |
C4—C5—C6—N3 | −177.7 (3) | C5—C6—N3—O7 | −24.9 (4) |
O1—C1—C6—C5 | 178.0 (3) | C1—C6—N3—O7 | 154.4 (3) |
C2—C1—C6—C5 | −2.3 (4) | C8—C7—N4—N5 | 0.1 (4) |
O1—C1—C6—N3 | −1.3 (4) | C7—N4—N5—C9 | −0.1 (3) |
C2—C1—C6—N3 | 178.5 (2) | C8—C9—N5—N4 | 0.0 (4) |
N4—C7—C8—C9 | −0.2 (4) | C11—C10—N6—N7 | 0.2 (4) |
C7—C8—C9—N5 | 0.1 (4) | C11—C12—N7—N6 | −0.1 (4) |
N6—C10—C11—C12 | −0.2 (4) | C10—N6—N7—C12 | −0.1 (4) |
D—H···A | D—H | H···A | D···A | D—H···A |
N4—H4A···N6 | 0.86 (1) | 1.81 (1) | 2.663 (3) | 173 (7) |
N5—H5A···O1i | 0.87 (1) | 1.95 (1) | 2.789 (3) | 163 (3) |
N5—H5A···O6i | 0.87 (1) | 2.42 (3) | 2.961 (4) | 121 (3) |
N6—H6A···N4 | 0.86 (1) | 1.81 (1) | 2.663 (3) | 174 (7) |
N7—H7A···O1 | 0.86 (1) | 2.04 (2) | 2.864 (3) | 160 (3) |
N7—H7A···O2 | 0.86 (1) | 2.29 (3) | 2.841 (3) | 122 (3) |
C12—H12···O4ii | 0.93 | 2.61 | 3.512 (5) | 165 |
Symmetry codes: (i) x+1, y, z; (ii) −x, −y+2, −z+1. |
Acknowledgements
We thank Dr Xiang-gao Meng for his helpful discussions about this crystal structure.
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