The title molecule has inversion symmetry, adopting the shape of a St Andrew’s cross. It shows dihedral angles between adjacent aryl units of around 50° whereas torsion angles of ca 10° are found along the arylene vinylene path.
Keywords: crystal structure, heterocycles, conjugated oligomers
Abstract
The molecule of the title compound, C30H22N4, exhibits inversion symmetry adopting the shape of a St Andrew’s Cross. It shows dihedral angles between adjacent aryl units of around 50° whereas torsion angles of ca 10° are found along the arylene vinylene path.
Structure description
The title compound 2,5-(E,E)-distyryl-3,6-di-(2-pyridyl)pyrazine, C30H22N4, was prepared as a reference chromophore in a project on pyrazine-centered materials, solvatochromic dyes (Schmitt et al., 2008 ▸, Wink & Detert, 2013 ▸) and liquid crystals (Röder et al., 2019 ▸; Schmitt et al., 2011 ▸).
The molecule has the shape of a centrosymmetrical St Andrew’s cross (Fig. 1 ▸). The central pyrazine ring as well as the vinylene groups and the peripheral pyridine and phenyl rings are totally planar. A dihedral angle of 48.07 (6)° at the teraryl axis is nearly identical to those in a related compound with phenyl rings (50.8, 48.6°, Schmitt et al., 2013 ▸). Torsion angles along the distyryl axis are −170.21 (15)°, (phenyl-vinyl) and −169.56 (14)° (vinyl-pyrazine). The packing is shown in Fig. 2 ▸.
Figure 1.
Perspective view of the title compound. Displacement ellipsoids are drawn at the 50% probability level. The second part of the molecule is generated by the symmetry operation 1 − x, 1 − y, 1 − z.
Figure 2.
Partial packing diagram of the title compound. View along the a axis.
Synthesis and crystallization
The title compound was prepared from 2,5-dimethyl-3,6-di(2-pyridyl)pyrazine (Kolb, 1896 ▸) (0.08 g) and benzaldehyde (0.13 g) in 35 ml of DMF by the action of 0.34 g potassium t-butylate. The base was added in portions to the stirred and cooled (30 min at 273 K) solution. After 4 h at ambient temperature, the mixture was poured into water, extracted with ethyl acetate and the organic layers were washed, dried (Na2SO4) and concentrated. Purification by chromatography on solica gel with toluene/ethyl acetate (20/1) as eluent, R f = 0.33. Yield: 40 mg, 30%.
1H NMR (CDCl3, 400 MHz): 8.83 (dd, J = 4.9 Hz, J = 1.5 Hz, 2 H), 8.23 (d, J = 7.8 Hz, 2 H), 8.03 (s = 2d, J = 16.1 Hz, 4 H), 7.95 (dt, J = 7.8 Hz, J = 1.9 Hz, 2 H), 7.58 (d, 4 H), 7.43 (ddd, J = 7.8 Hz, J = 4.9 Hz, J = 1.5 Hz, 2H), 7.36 (t, J = 7.3 Hz, 4 H), 7.29 (dt, J = 7.3 Hz, J = 1.4 Hz, 2H); 13C NMR (CDCl3, 100 MHz): 157.1, 148.9, 148.3, 145.9, 137.3, 137.0, 135.2, 128.7, 127.6, 125.4, 124.7, 123.6; IR (ATR): 3009, 2988, 2926, 2853, 2688, 1473, 1448, 1276, 1254, 1135, 1086, 1040, 962, 901, 89, 752, 699, 621; MS (APCI): calculated for C30H22N4+H+): 439.1917, found 439.1908.
Refinement
Crystal data, data collection and structure refinement details are summarized in Table 1 ▸.
Table 1. Experimental details.
| Crystal data | |
| Chemical formula | C30H22N4 |
| M r | 438.51 |
| Crystal system, space group | Monoclinic, P21/c |
| Temperature (K) | 193 |
| a, b, c (Å) | 7.0953 (8), 8.9310 (8), 18.219 (2) |
| β (°) | 95.490 (9) |
| V (Å3) | 1149.2 (2) |
| Z | 2 |
| Radiation type | Mo Kα |
| μ (mm−1) | 0.08 |
| Crystal size (mm) | 0.53 × 0.32 × 0.06 |
| Data collection | |
| Diffractometer | STOE IPDS 2T |
| Absorption correction | – |
| No. of measured, independent and observed [I > 2σ(I)] reflections | 5878, 2718, 1622 |
| R int | 0.029 |
| (sin θ/λ)max (Å−1) | 0.659 |
| Refinement | |
| R[F 2 > 2σ(F 2)], wR(F 2), S | 0.043, 0.110, 0.99 |
| No. of reflections | 2718 |
| No. of parameters | 154 |
| H-atom treatment | H-atom parameters constrained |
| Δρmax, Δρmin (e Å−3) | 0.17, −0.14 |
Supplementary Material
Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S2414314620003727/bt4090sup1.cif
Structure factors: contains datablock(s) I. DOI: 10.1107/S2414314620003727/bt4090Isup2.hkl
Supporting information file. DOI: 10.1107/S2414314620003727/bt4090Isup3.cml
CCDC reference: 1989990
Additional supporting information: crystallographic information; 3D view; checkCIF report
full crystallographic data
Crystal data
| C30H22N4 | F(000) = 460 |
| Mr = 438.51 | Dx = 1.267 Mg m−3 |
| Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
| a = 7.0953 (8) Å | Cell parameters from 3402 reflections |
| b = 8.9310 (8) Å | θ = 2.5–28.2° |
| c = 18.219 (2) Å | µ = 0.08 mm−1 |
| β = 95.490 (9)° | T = 193 K |
| V = 1149.2 (2) Å3 | Plate, yellow |
| Z = 2 | 0.53 × 0.32 × 0.06 mm |
Data collection
| STOE IPDS 2T diffractometer | 1622 reflections with I > 2σ(I) |
| Radiation source: sealed X-ray tube, 12 x 0.4 mm long-fine focus | Rint = 0.029 |
| Detector resolution: 6.67 pixels mm-1 | θmax = 27.9°, θmin = 2.5° |
| rotation method scans | h = −9→9 |
| 5878 measured reflections | k = −10→11 |
| 2718 independent reflections | l = −23→21 |
Refinement
| Refinement on F2 | Primary atom site location: structure-invariant direct methods |
| Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
| R[F2 > 2σ(F2)] = 0.043 | H-atom parameters constrained |
| wR(F2) = 0.110 | w = 1/[σ2(Fo2) + (0.0551P)2] where P = (Fo2 + 2Fc2)/3 |
| S = 0.99 | (Δ/σ)max < 0.001 |
| 2718 reflections | Δρmax = 0.17 e Å−3 |
| 154 parameters | Δρmin = −0.14 e Å−3 |
| 0 restraints |
Special details
| 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. |
| Refinement. Hydrogen atoms attached to carbons were placed at calculated positions and were refined in the riding-model approximation with C–H = 0.95 Å, and with Uiso(H) = 1.2 Ueq(C). |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)
| x | y | z | Uiso*/Ueq | ||
| N1 | 0.56710 (15) | 0.38847 (13) | 0.45640 (6) | 0.0371 (3) | |
| C2 | 0.65303 (18) | 0.52229 (16) | 0.46177 (7) | 0.0356 (3) | |
| C3 | 0.58305 (19) | 0.63537 (16) | 0.50618 (7) | 0.0349 (3) | |
| C4 | 0.82169 (19) | 0.54154 (17) | 0.42232 (8) | 0.0377 (3) | |
| H4 | 0.898305 | 0.627307 | 0.433494 | 0.045* | |
| C5 | 0.8747 (2) | 0.44665 (17) | 0.37180 (8) | 0.0394 (3) | |
| H5 | 0.796135 | 0.361702 | 0.361337 | 0.047* | |
| C6 | 1.04162 (19) | 0.45956 (17) | 0.33065 (8) | 0.0385 (4) | |
| C7 | 1.0601 (2) | 0.3624 (2) | 0.27172 (8) | 0.0524 (4) | |
| H7 | 0.965446 | 0.288996 | 0.259487 | 0.063* | |
| C8 | 1.2135 (3) | 0.3716 (2) | 0.23111 (10) | 0.0691 (6) | |
| H8 | 1.223164 | 0.305063 | 0.190953 | 0.083* | |
| C9 | 1.3524 (3) | 0.4758 (3) | 0.24812 (10) | 0.0697 (6) | |
| H9 | 1.458129 | 0.481619 | 0.219953 | 0.084* | |
| C10 | 1.3377 (2) | 0.5724 (2) | 0.30648 (10) | 0.0585 (5) | |
| H10 | 1.433770 | 0.644817 | 0.318544 | 0.070* | |
| C11 | 1.1840 (2) | 0.56400 (19) | 0.34735 (8) | 0.0444 (4) | |
| H11 | 1.175609 | 0.630726 | 0.387515 | 0.053* | |
| C12 | 0.66436 (18) | 0.78758 (17) | 0.51362 (8) | 0.0364 (3) | |
| N13 | 0.69586 (16) | 0.85842 (14) | 0.45085 (7) | 0.0415 (3) | |
| C14 | 0.7551 (2) | 1.00017 (19) | 0.45675 (10) | 0.0487 (4) | |
| H14 | 0.774730 | 1.052537 | 0.412735 | 0.058* | |
| C15 | 0.7892 (2) | 1.0746 (2) | 0.52227 (11) | 0.0545 (5) | |
| H15 | 0.831478 | 1.175580 | 0.523436 | 0.065* | |
| C16 | 0.7610 (2) | 1.0003 (2) | 0.58648 (10) | 0.0555 (5) | |
| H16 | 0.786532 | 1.048282 | 0.632899 | 0.067* | |
| C17 | 0.6949 (2) | 0.85434 (19) | 0.58234 (9) | 0.0467 (4) | |
| H17 | 0.671004 | 0.801209 | 0.625662 | 0.056* |
Atomic displacement parameters (Å2)
| U11 | U22 | U33 | U12 | U13 | U23 | |
| N1 | 0.0403 (6) | 0.0387 (7) | 0.0329 (6) | 0.0050 (5) | 0.0070 (5) | 0.0027 (5) |
| C2 | 0.0356 (7) | 0.0408 (9) | 0.0310 (7) | 0.0055 (6) | 0.0066 (6) | 0.0059 (6) |
| C3 | 0.0365 (7) | 0.0376 (8) | 0.0312 (7) | 0.0064 (6) | 0.0056 (5) | 0.0055 (6) |
| C4 | 0.0389 (7) | 0.0382 (8) | 0.0371 (7) | 0.0031 (6) | 0.0087 (6) | 0.0026 (7) |
| C5 | 0.0414 (7) | 0.0412 (8) | 0.0362 (8) | 0.0023 (7) | 0.0069 (6) | 0.0029 (7) |
| C6 | 0.0382 (7) | 0.0472 (9) | 0.0306 (7) | 0.0095 (6) | 0.0054 (5) | 0.0028 (7) |
| C7 | 0.0546 (10) | 0.0671 (12) | 0.0359 (8) | 0.0094 (8) | 0.0072 (7) | −0.0088 (8) |
| C8 | 0.0652 (12) | 0.1046 (17) | 0.0397 (9) | 0.0236 (12) | 0.0156 (8) | −0.0111 (10) |
| C9 | 0.0503 (10) | 0.1129 (18) | 0.0494 (10) | 0.0206 (12) | 0.0227 (8) | 0.0132 (12) |
| C10 | 0.0414 (8) | 0.0791 (13) | 0.0562 (10) | 0.0031 (9) | 0.0107 (7) | 0.0166 (10) |
| C11 | 0.0429 (8) | 0.0512 (10) | 0.0400 (8) | 0.0060 (7) | 0.0079 (6) | 0.0034 (7) |
| C12 | 0.0312 (7) | 0.0392 (8) | 0.0391 (8) | 0.0059 (6) | 0.0057 (6) | 0.0000 (7) |
| N13 | 0.0395 (7) | 0.0396 (7) | 0.0462 (7) | −0.0004 (6) | 0.0073 (5) | 0.0044 (6) |
| C14 | 0.0401 (8) | 0.0426 (10) | 0.0644 (11) | 0.0005 (7) | 0.0093 (7) | 0.0066 (8) |
| C15 | 0.0393 (8) | 0.0422 (10) | 0.0820 (13) | 0.0020 (7) | 0.0065 (8) | −0.0087 (10) |
| C16 | 0.0446 (9) | 0.0606 (11) | 0.0602 (11) | 0.0061 (8) | 0.0001 (8) | −0.0226 (9) |
| C17 | 0.0437 (8) | 0.0532 (10) | 0.0433 (9) | 0.0070 (7) | 0.0049 (6) | −0.0042 (8) |
Geometric parameters (Å, º)
| N1—C3i | 1.3356 (17) | C9—C10 | 1.381 (3) |
| N1—C2 | 1.3410 (18) | C9—H9 | 0.9500 |
| C2—C3 | 1.4136 (19) | C10—C11 | 1.380 (2) |
| C2—C4 | 1.4638 (19) | C10—H10 | 0.9500 |
| C3—C12 | 1.478 (2) | C11—H11 | 0.9500 |
| C4—C5 | 1.332 (2) | C12—N13 | 1.3442 (18) |
| C4—H4 | 0.9500 | C12—C17 | 1.385 (2) |
| C5—C6 | 1.4655 (19) | N13—C14 | 1.335 (2) |
| C5—H5 | 0.9500 | C14—C15 | 1.368 (2) |
| C6—C11 | 1.387 (2) | C14—H14 | 0.9500 |
| C6—C7 | 1.396 (2) | C15—C16 | 1.376 (3) |
| C7—C8 | 1.376 (2) | C15—H15 | 0.9500 |
| C7—H7 | 0.9500 | C16—C17 | 1.385 (2) |
| C8—C9 | 1.369 (3) | C16—H16 | 0.9500 |
| C8—H8 | 0.9500 | C17—H17 | 0.9500 |
| C3i—N1—C2 | 118.95 (12) | C10—C9—H9 | 120.2 |
| N1—C2—C3 | 119.76 (12) | C11—C10—C9 | 120.21 (17) |
| N1—C2—C4 | 117.14 (13) | C11—C10—H10 | 119.9 |
| C3—C2—C4 | 123.06 (13) | C9—C10—H10 | 119.9 |
| N1i—C3—C2 | 121.29 (13) | C10—C11—C6 | 120.97 (16) |
| N1i—C3—C12 | 115.04 (12) | C10—C11—H11 | 119.5 |
| C2—C3—C12 | 123.65 (12) | C6—C11—H11 | 119.5 |
| C5—C4—C2 | 124.26 (14) | N13—C12—C17 | 122.83 (15) |
| C5—C4—H4 | 117.9 | N13—C12—C3 | 116.76 (13) |
| C2—C4—H4 | 117.9 | C17—C12—C3 | 120.31 (14) |
| C4—C5—C6 | 126.81 (14) | C14—N13—C12 | 117.03 (14) |
| C4—C5—H5 | 116.6 | N13—C14—C15 | 124.01 (16) |
| C6—C5—H5 | 116.6 | N13—C14—H14 | 118.0 |
| C11—C6—C7 | 117.79 (14) | C15—C14—H14 | 118.0 |
| C11—C6—C5 | 123.22 (13) | C14—C15—C16 | 118.66 (17) |
| C7—C6—C5 | 118.99 (14) | C14—C15—H15 | 120.7 |
| C8—C7—C6 | 120.94 (17) | C16—C15—H15 | 120.7 |
| C8—C7—H7 | 119.5 | C15—C16—C17 | 118.92 (16) |
| C6—C7—H7 | 119.5 | C15—C16—H16 | 120.5 |
| C9—C8—C7 | 120.52 (17) | C17—C16—H16 | 120.5 |
| C9—C8—H8 | 119.7 | C16—C17—C12 | 118.51 (16) |
| C7—C8—H8 | 119.7 | C16—C17—H17 | 120.7 |
| C8—C9—C10 | 119.56 (16) | C12—C17—H17 | 120.7 |
| C8—C9—H9 | 120.2 | ||
| C3i—N1—C2—C3 | −0.4 (2) | C9—C10—C11—C6 | −0.2 (2) |
| C3i—N1—C2—C4 | 177.52 (12) | C7—C6—C11—C10 | 0.7 (2) |
| N1—C2—C3—N1i | 0.4 (2) | C5—C6—C11—C10 | −179.48 (14) |
| C4—C2—C3—N1i | −177.38 (12) | N1i—C3—C12—N13 | −130.40 (13) |
| N1—C2—C3—C12 | −177.97 (12) | C2—C3—C12—N13 | 48.11 (17) |
| C4—C2—C3—C12 | 4.2 (2) | N1i—C3—C12—C17 | 46.03 (17) |
| N1—C2—C4—C5 | 12.6 (2) | C2—C3—C12—C17 | −135.47 (14) |
| C3—C2—C4—C5 | −169.56 (13) | C17—C12—N13—C14 | −1.5 (2) |
| C2—C4—C5—C6 | −179.88 (13) | C3—C12—N13—C14 | 174.83 (12) |
| C4—C5—C6—C11 | 9.9 (2) | C12—N13—C14—C15 | 1.6 (2) |
| C4—C5—C6—C7 | −170.21 (15) | N13—C14—C15—C16 | −0.1 (2) |
| C11—C6—C7—C8 | −0.8 (2) | C14—C15—C16—C17 | −1.6 (2) |
| C5—C6—C7—C8 | 179.34 (15) | C15—C16—C17—C12 | 1.7 (2) |
| C6—C7—C8—C9 | 0.5 (3) | N13—C12—C17—C16 | −0.1 (2) |
| C7—C8—C9—C10 | −0.1 (3) | C3—C12—C17—C16 | −176.32 (13) |
| C8—C9—C10—C11 | −0.1 (3) |
Symmetry code: (i) −x+1, −y+1, −z+1.
References
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S2414314620003727/bt4090sup1.cif
Structure factors: contains datablock(s) I. DOI: 10.1107/S2414314620003727/bt4090Isup2.hkl
Supporting information file. DOI: 10.1107/S2414314620003727/bt4090Isup3.cml
CCDC reference: 1989990
Additional supporting information: crystallographic information; 3D view; checkCIF report


