Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807019642/dn2164sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536807019642/dn2164Isup2.hkl |
CCDC reference: 651369
All reagents were of analytical grade and used without further purification. Dimethyl-1H-pyrazole-3,5-dicarboxylate was prepared by the general procedure of Schenck et al. (1985). Colorless single crystals were grown from slow evaporation of the saturated MeOH solution of the compound. Analysis found: C 45.64, H 4.40, N 15.25%.; calculated for C7H8N2O4: C 45.66, H 4.38, N 15.21%.
All H atoms attached to C atoms and N atom were fixed geometrically and treated as riding with C—H = 0.93Å (aromatic) or 0.96Å (methyl) and N—H = 0.86Å with Uiso(H) = 1.2Ueq(CH or NH) or Uiso(H) = 1.5Ueq(CH3).
Recently, there has been much interest in the study of crystal engineering of supramolecular architectures using N-donor ligands (Zheng et al., 2003; Peng et al., 2006). The title compound, C7H8N2O4, is an important organic intermediate and precursor of bi- or polydentate ligands which have been reported (Schenck et al., 1985; Ardizzoia et al., 2002).
The asymmetric unit contains two molecules linked together via intermolecular N—H··· O(2.80 Å) and N—H··· N (2.92 Å) hydrogen bonds and forming a pseudo dimer(Fig. 1). Futhermore intermolecular C—H··· O contacts (3.24–3.47 Å) satisfy the definition of weak hydrogen bonds as proposed by Taylor et al. (1982) and Desiraju et al. (1999), and resulted in a two dimensional network (Fig. 2). Interestingly, all of the nonH atoms are coplanar. Although the interpalanar distances, 3.25 Å, between stacked pyrazole molecules might indicate π···π stacking, the centroid to centroid distance between pyrazlole rings, 3.70 Å, corresponds to a large offset angle of 28.6 ° which prevents such π···π stacking.
For general background, see: Zheng et al., 2003; Peng et al., 2006; Schenck et al., 1985; Ardizzoia et al., 2002. For structure analysis tools used, see: Taylor et al., 1982; Desiraju et al.,1999.
Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997a); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997a); molecular graphics: ORTEPIII (Burnett & Johnson, 1996), ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 2003); software used to prepare material for publication: SHELXTL (Sheldrick, 1997b).
C7H8N2O4 | F(000) = 768 |
Mr = 184.15 | Dx = 1.457 Mg m−3 |
Orthorhombic, Pnma | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ac 2n | Cell parameters from 2089 reflections |
a = 10.9563 (14) Å | θ = 5.1–51.9° |
b = 6.4983 (8) Å | µ = 0.12 mm−1 |
c = 23.589 (3) Å | T = 293 K |
V = 1679.5 (4) Å3 | Prismatic, colorless |
Z = 8 | 0.49 × 0.34 × 0.13 mm |
Bruker SMART CCD area-detector diffractometer | 1614 independent reflections |
Radiation source: fine-focus sealed tube | 1196 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.116 |
φ and ω scans | θmax = 25.1°, θmin = 2.1° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −13→11 |
Tmin = 0.943, Tmax = 0.985 | k = −7→7 |
8106 measured reflections | l = −26→28 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.044 | H-atom parameters constrained |
wR(F2) = 0.106 | w = 1/[σ2(Fo2) + (0.0538P)2] where P = (Fo2 + 2Fc2)/3 |
S = 0.97 | (Δ/σ)max < 0.001 |
1614 reflections | Δρmax = 0.17 e Å−3 |
162 parameters | Δρmin = −0.24 e Å−3 |
5 restraints | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.020 (3) |
C7H8N2O4 | V = 1679.5 (4) Å3 |
Mr = 184.15 | Z = 8 |
Orthorhombic, Pnma | Mo Kα radiation |
a = 10.9563 (14) Å | µ = 0.12 mm−1 |
b = 6.4983 (8) Å | T = 293 K |
c = 23.589 (3) Å | 0.49 × 0.34 × 0.13 mm |
Bruker SMART CCD area-detector diffractometer | 1614 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 1196 reflections with I > 2σ(I) |
Tmin = 0.943, Tmax = 0.985 | Rint = 0.116 |
8106 measured reflections |
R[F2 > 2σ(F2)] = 0.044 | 5 restraints |
wR(F2) = 0.106 | H-atom parameters constrained |
S = 0.97 | Δρmax = 0.17 e Å−3 |
1614 reflections | Δρmin = −0.24 e Å−3 |
162 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. Highest peak 0.17 at 0.6417 0.2500 0.6281 [0.90 A from N2] Deepest hole -0.24 at 0.3595 0.2500 0.4390 [0.95 A from C10] |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
O1 | 0.80198 (16) | 0.2500 | 0.71010 (7) | 0.0603 (5) | |
O2 | 0.98429 (15) | 0.2500 | 0.66789 (6) | 0.0566 (5) | |
O3 | 0.71755 (15) | 0.2500 | 0.42420 (7) | 0.0554 (5) | |
O4 | 0.91928 (14) | 0.2500 | 0.43727 (7) | 0.0509 (5) | |
O5 | 0.19936 (16) | 0.2500 | 0.56690 (7) | 0.0651 (6) | |
O6 | 0.40030 (16) | 0.2500 | 0.58550 (7) | 0.0633 (6) | |
O7 | 0.42515 (16) | 0.2500 | 0.30600 (7) | 0.0669 (6) | |
O8 | 0.22351 (14) | 0.2500 | 0.32051 (6) | 0.0489 (5) | |
N1 | 0.68713 (16) | 0.2500 | 0.54353 (8) | 0.0391 (5) | |
H1 | 0.6186 | 0.2500 | 0.5258 | 0.047* | |
N2 | 0.69628 (17) | 0.2500 | 0.59972 (8) | 0.0405 (5) | |
N3 | 0.46241 (17) | 0.2500 | 0.42244 (8) | 0.0437 (5) | |
H3 | 0.5287 | 0.2500 | 0.4029 | 0.052* | |
N4 | 0.46048 (16) | 0.2500 | 0.47848 (8) | 0.0426 (5) | |
C1 | 0.8175 (2) | 0.2500 | 0.60908 (9) | 0.0377 (6) | |
C2 | 0.8834 (2) | 0.2500 | 0.55897 (9) | 0.0391 (6) | |
H2 | 0.9678 | 0.2500 | 0.5548 | 0.047* | |
C3 | 0.79727 (19) | 0.2500 | 0.51709 (10) | 0.0386 (6) | |
C4 | 0.8624 (2) | 0.2500 | 0.66784 (10) | 0.0418 (6) | |
C5 | 1.0440 (3) | 0.2500 | 0.72248 (10) | 0.0685 (9) | |
H5A | 1.0381 | 0.1155 | 0.7391 | 0.103* | 0.50 |
H5B | 1.0052 | 0.3486 | 0.7468 | 0.103* | 0.50 |
H5C | 1.1284 | 0.2859 | 0.7178 | 0.103* | 0.50 |
C6 | 0.8042 (2) | 0.2500 | 0.45525 (10) | 0.0404 (6) | |
C7 | 0.9345 (2) | 0.2500 | 0.37656 (11) | 0.0694 (9) | |
H7A | 1.0165 | 0.2097 | 0.3673 | 0.104* | 0.50 |
H7B | 0.9192 | 0.3856 | 0.3621 | 0.104* | 0.50 |
H7C | 0.8781 | 0.1547 | 0.3598 | 0.104* | 0.50 |
C8 | 0.3416 (2) | 0.2500 | 0.49172 (9) | 0.0361 (5) | |
C9 | 0.2694 (2) | 0.2500 | 0.44305 (9) | 0.0366 (5) | |
H9 | 0.1846 | 0.2500 | 0.4411 | 0.044* | |
C10 | 0.3500 (2) | 0.2500 | 0.39891 (10) | 0.0385 (6) | |
C11 | 0.3041 (2) | 0.2500 | 0.55114 (10) | 0.0439 (6) | |
C12 | 0.3778 (3) | 0.2500 | 0.64513 (11) | 0.0934 (12) | |
H12A | 0.3561 | 0.1137 | 0.6571 | 0.140* | 0.50 |
H12B | 0.3122 | 0.3429 | 0.6536 | 0.140* | 0.50 |
H12C | 0.4501 | 0.2934 | 0.6648 | 0.140* | 0.50 |
C13 | 0.3392 (2) | 0.2500 | 0.33725 (10) | 0.0439 (6) | |
C14 | 0.2036 (3) | 0.2500 | 0.25984 (11) | 0.0634 (8) | |
H14A | 0.2585 | 0.1541 | 0.2422 | 0.095* | 0.50 |
H14B | 0.2183 | 0.3854 | 0.2451 | 0.095* | 0.50 |
H14C | 0.1209 | 0.2104 | 0.2520 | 0.095* | 0.50 |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0492 (11) | 0.0942 (14) | 0.0374 (10) | 0.000 | 0.0117 (9) | 0.000 |
O2 | 0.0354 (10) | 0.1019 (14) | 0.0326 (9) | 0.000 | −0.0037 (7) | 0.000 |
O3 | 0.0294 (10) | 0.0929 (14) | 0.0440 (10) | 0.000 | −0.0048 (8) | 0.000 |
O4 | 0.0277 (9) | 0.0867 (13) | 0.0382 (9) | 0.000 | 0.0004 (7) | 0.000 |
O5 | 0.0399 (12) | 0.1052 (16) | 0.0502 (11) | 0.000 | 0.0107 (9) | 0.000 |
O6 | 0.0440 (11) | 0.1088 (15) | 0.0371 (10) | 0.000 | −0.0066 (9) | 0.000 |
O7 | 0.0404 (11) | 0.1171 (17) | 0.0433 (11) | 0.000 | 0.0096 (9) | 0.000 |
O8 | 0.0360 (10) | 0.0784 (12) | 0.0325 (9) | 0.000 | −0.0066 (7) | 0.000 |
N1 | 0.0261 (10) | 0.0509 (12) | 0.0402 (11) | 0.000 | −0.0041 (8) | 0.000 |
N2 | 0.0329 (12) | 0.0504 (12) | 0.0384 (11) | 0.000 | 0.0005 (9) | 0.000 |
N3 | 0.0260 (11) | 0.0687 (14) | 0.0365 (11) | 0.000 | 0.0016 (8) | 0.000 |
N4 | 0.0284 (11) | 0.0613 (13) | 0.0380 (11) | 0.000 | −0.0027 (9) | 0.000 |
C1 | 0.0273 (12) | 0.0474 (14) | 0.0384 (13) | 0.000 | −0.0028 (10) | 0.000 |
C2 | 0.0257 (12) | 0.0530 (15) | 0.0387 (13) | 0.000 | −0.0004 (10) | 0.000 |
C3 | 0.0285 (12) | 0.0452 (14) | 0.0421 (13) | 0.000 | −0.0005 (10) | 0.000 |
C4 | 0.0334 (13) | 0.0479 (15) | 0.0441 (14) | 0.000 | 0.0032 (11) | 0.000 |
C5 | 0.0526 (18) | 0.115 (3) | 0.0380 (15) | 0.000 | −0.0143 (13) | 0.000 |
C6 | 0.0289 (13) | 0.0527 (15) | 0.0396 (13) | 0.000 | −0.0010 (11) | 0.000 |
C7 | 0.0432 (17) | 0.121 (3) | 0.0442 (16) | 0.000 | 0.0064 (13) | 0.000 |
C8 | 0.0279 (12) | 0.0412 (13) | 0.0391 (13) | 0.000 | −0.0016 (10) | 0.000 |
C9 | 0.0267 (12) | 0.0448 (13) | 0.0384 (13) | 0.000 | −0.0040 (10) | 0.000 |
C10 | 0.0278 (12) | 0.0459 (14) | 0.0418 (13) | 0.000 | −0.0034 (11) | 0.000 |
C11 | 0.0370 (15) | 0.0541 (15) | 0.0406 (14) | 0.000 | −0.0031 (11) | 0.000 |
C12 | 0.086 (3) | 0.161 (3) | 0.0332 (16) | 0.000 | −0.0088 (17) | 0.000 |
C13 | 0.0353 (14) | 0.0579 (16) | 0.0384 (14) | 0.000 | 0.0014 (11) | 0.000 |
C14 | 0.0646 (19) | 0.088 (2) | 0.0374 (14) | 0.000 | −0.0151 (14) | 0.000 |
O1—C4 | 1.197 (3) | C1—C4 | 1.471 (3) |
O2—C4 | 1.335 (3) | C2—C3 | 1.366 (3) |
O2—C5 | 1.444 (3) | C2—H2 | 0.9300 |
O3—C6 | 1.199 (3) | C3—C6 | 1.461 (3) |
O4—C6 | 1.330 (3) | C5—H5A | 0.9600 |
O4—C7 | 1.442 (3) | C5—H5B | 0.9600 |
O5—C11 | 1.206 (3) | C5—H5C | 0.9600 |
O6—C11 | 1.330 (3) | C7—H7A | 0.9600 |
O6—C12 | 1.428 (3) | C7—H7B | 0.9600 |
O7—C13 | 1.196 (3) | C7—H7C | 0.9600 |
O8—C13 | 1.327 (3) | C8—C9 | 1.394 (3) |
O8—C14 | 1.448 (3) | C8—C11 | 1.461 (3) |
N1—N2 | 1.329 (3) | C9—C10 | 1.366 (3) |
N1—C3 | 1.358 (3) | C9—H9 | 0.9300 |
N1—H1 | 0.8600 | C10—C13 | 1.459 (3) |
N2—C1 | 1.347 (3) | C12—H12A | 0.9600 |
N3—N4 | 1.322 (3) | C12—H12B | 0.9600 |
N3—C10 | 1.351 (3) | C12—H12C | 0.9600 |
N3—H3 | 0.8600 | C14—H14A | 0.9600 |
N4—C8 | 1.340 (3) | C14—H14B | 0.9600 |
C1—C2 | 1.385 (3) | C14—H14C | 0.9600 |
C4—O2—C5 | 116.98 (19) | O4—C7—H7A | 109.5 |
C6—O4—C7 | 115.25 (18) | O4—C7—H7B | 109.5 |
C11—O6—C12 | 117.6 (2) | H7A—C7—H7B | 109.5 |
C13—O8—C14 | 115.95 (19) | O4—C7—H7C | 109.5 |
N2—N1—C3 | 113.02 (18) | H7A—C7—H7C | 109.5 |
N2—N1—H1 | 123.5 | H7B—C7—H7C | 109.5 |
C3—N1—H1 | 123.5 | N4—C8—C9 | 111.1 (2) |
N1—N2—C1 | 103.76 (18) | N4—C8—C11 | 119.8 (2) |
N4—N3—C10 | 113.34 (19) | C9—C8—C11 | 129.1 (2) |
N4—N3—H3 | 123.3 | C10—C9—C8 | 105.1 (2) |
C10—N3—H3 | 123.3 | C10—C9—H9 | 127.4 |
N3—N4—C8 | 104.40 (18) | C8—C9—H9 | 127.4 |
N2—C1—C2 | 111.97 (19) | N3—C10—C9 | 106.1 (2) |
N2—C1—C4 | 119.0 (2) | N3—C10—C13 | 118.9 (2) |
C2—C1—C4 | 129.1 (2) | C9—C10—C13 | 135.0 (2) |
C3—C2—C1 | 104.9 (2) | O5—C11—O6 | 124.5 (2) |
C3—C2—H2 | 127.5 | O5—C11—C8 | 124.3 (2) |
C1—C2—H2 | 127.5 | O6—C11—C8 | 111.2 (2) |
N1—C3—C2 | 106.34 (19) | O6—C12—H12A | 109.5 |
N1—C3—C6 | 120.33 (19) | O6—C12—H12B | 109.5 |
C2—C3—C6 | 133.3 (2) | H12A—C12—H12B | 109.5 |
O1—C4—O2 | 123.5 (2) | O6—C12—H12C | 109.5 |
O1—C4—C1 | 126.9 (2) | H12A—C12—H12C | 109.5 |
O2—C4—C1 | 109.6 (2) | H12B—C12—H12C | 109.5 |
O2—C5—H5A | 109.5 | O7—C13—O8 | 124.7 (2) |
O2—C5—H5B | 109.5 | O7—C13—C10 | 123.4 (2) |
H5A—C5—H5B | 109.5 | O8—C13—C10 | 112.0 (2) |
O2—C5—H5C | 109.5 | O8—C14—H14A | 109.5 |
H5A—C5—H5C | 109.5 | O8—C14—H14B | 109.5 |
H5B—C5—H5C | 109.5 | H14A—C14—H14B | 109.5 |
O3—C6—O4 | 123.8 (2) | O8—C14—H14C | 109.5 |
O3—C6—C3 | 124.7 (2) | H14A—C14—H14C | 109.5 |
O4—C6—C3 | 111.58 (19) | H14B—C14—H14C | 109.5 |
C3—N1—N2—C1 | 0.0 | C2—C3—C6—O4 | 0.0 |
C10—N3—N4—C8 | 0.0 | N3—N4—C8—C9 | 0.0 |
N1—N2—C1—C2 | 0.0 | N3—N4—C8—C11 | 180.0 |
N1—N2—C1—C4 | 180.0 | N4—C8—C9—C10 | 0.0 |
N2—C1—C2—C3 | 0.0 | C11—C8—C9—C10 | 180.0 |
C4—C1—C2—C3 | 180.0 | N4—N3—C10—C9 | 0.0 |
N2—N1—C3—C2 | 0.0 | N4—N3—C10—C13 | 180.0 |
N2—N1—C3—C6 | 180.0 | C8—C9—C10—N3 | 0.0 |
C1—C2—C3—N1 | 0.0 | C8—C9—C10—C13 | 180.0 |
C1—C2—C3—C6 | 180.0 | C12—O6—C11—O5 | 0.0 |
C5—O2—C4—O1 | 0.0 | C12—O6—C11—C8 | 180.0 |
C5—O2—C4—C1 | 180.0 | N4—C8—C11—O5 | 180.0 |
N2—C1—C4—O1 | 0.000 (1) | C9—C8—C11—O5 | 0.0 |
C2—C1—C4—O1 | 180.0 | N4—C8—C11—O6 | 0.0 |
N2—C1—C4—O2 | 180.0 | C9—C8—C11—O6 | 180.0 |
C2—C1—C4—O2 | 0.0 | C14—O8—C13—O7 | 0.0 |
C7—O4—C6—O3 | 0.0 | C14—O8—C13—C10 | 180.0 |
C7—O4—C6—C3 | 180.0 | N3—C10—C13—O7 | 0.0 |
N1—C3—C6—O3 | 0.0 | C9—C10—C13—O7 | 180.0 |
C2—C3—C6—O3 | 180.0 | N3—C10—C13—O8 | 180.0 |
N1—C3—C6—O4 | 180.0 | C9—C10—C13—O8 | 0.0 |
D—H···A | D—H | H···A | D···A | D—H···A |
N3—H3···O3 | 0.86 | 2.13 | 2.796 (2) | 134 |
N1—H1···N4 | 0.86 | 2.06 | 2.919 (2) | 176 |
C2—H2···O5i | 0.93 | 2.55 | 3.467 (3) | 167 |
C7—H7A···O8i | 0.96 | 2.54 | 3.431 (3) | 155 |
C5—H5C···O1ii | 0.96 | 2.56 | 3.243 (3) | 128 |
C14—H14C···O7iii | 0.96 | 2.56 | 3.424 (3) | 150 |
Symmetry codes: (i) x+1, y, z; (ii) x+1/2, −y+1/2, −z+3/2; (iii) x−1/2, −y+1/2, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | C7H8N2O4 |
Mr | 184.15 |
Crystal system, space group | Orthorhombic, Pnma |
Temperature (K) | 293 |
a, b, c (Å) | 10.9563 (14), 6.4983 (8), 23.589 (3) |
V (Å3) | 1679.5 (4) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.12 |
Crystal size (mm) | 0.49 × 0.34 × 0.13 |
Data collection | |
Diffractometer | Bruker SMART CCD area-detector |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.943, 0.985 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 8106, 1614, 1196 |
Rint | 0.116 |
(sin θ/λ)max (Å−1) | 0.597 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.044, 0.106, 0.97 |
No. of reflections | 1614 |
No. of parameters | 162 |
No. of restraints | 5 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.17, −0.24 |
Computer programs: SMART (Bruker, 1998), SAINT (Bruker, 1998), SAINT, SHELXS97 (Sheldrick, 1997a), SHELXL97 (Sheldrick, 1997a), ORTEPIII (Burnett & Johnson, 1996), ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 2003), SHELXTL (Sheldrick, 1997b).
D—H···A | D—H | H···A | D···A | D—H···A |
N3—H3···O3 | 0.86 | 2.13 | 2.796 (2) | 133.9 |
N1—H1···N4 | 0.86 | 2.06 | 2.919 (2) | 176.4 |
C2—H2···O5i | 0.93 | 2.55 | 3.467 (3) | 167.4 |
C7—H7A···O8i | 0.96 | 2.54 | 3.431 (3) | 155.0 |
C5—H5C···O1ii | 0.96 | 2.56 | 3.243 (3) | 128.0 |
C14—H14C···O7iii | 0.96 | 2.56 | 3.424 (3) | 150.4 |
Symmetry codes: (i) x+1, y, z; (ii) x+1/2, −y+1/2, −z+3/2; (iii) x−1/2, −y+1/2, −z+1/2. |
Recently, there has been much interest in the study of crystal engineering of supramolecular architectures using N-donor ligands (Zheng et al., 2003; Peng et al., 2006). The title compound, C7H8N2O4, is an important organic intermediate and precursor of bi- or polydentate ligands which have been reported (Schenck et al., 1985; Ardizzoia et al., 2002).
The asymmetric unit contains two molecules linked together via intermolecular N—H··· O(2.80 Å) and N—H··· N (2.92 Å) hydrogen bonds and forming a pseudo dimer(Fig. 1). Futhermore intermolecular C—H··· O contacts (3.24–3.47 Å) satisfy the definition of weak hydrogen bonds as proposed by Taylor et al. (1982) and Desiraju et al. (1999), and resulted in a two dimensional network (Fig. 2). Interestingly, all of the nonH atoms are coplanar. Although the interpalanar distances, 3.25 Å, between stacked pyrazole molecules might indicate π···π stacking, the centroid to centroid distance between pyrazlole rings, 3.70 Å, corresponds to a large offset angle of 28.6 ° which prevents such π···π stacking.