organic compounds
Tetraethyl pyrazine-2,3,5,6-tetracarboxylate
aInstitute of Chemistry, University of Neuchâtel, Av. de Bellevaux 51, CH-2000 Neuchâtel, Switzerland, and bInstutute of Physics, University of Meuchâtel, rue Emile-Argand 11, CH-2000 neuchâtel, Switzerland
*Correspondence e-mail: helen.stoeckli-evans@unine.ch
The whole molecule of the title compound, C16H20N2O8, is generated by inversion symmetry. The adjacent carboxylate groups [C(=O)—O—C] are inclined to the pyrazine ring by 72.40 (10) and 19.64 (10)°, and to one another by 68.21 (12)°. In the crystal, molecules stack along the a-axis direction but there are no significant intermolecular interactions present.
CCDC reference: 1440891
Synthesis and crystallization
The title compound (Fig. 1) was prepared by the method of Mager & Berends (1960). Colourless crystals were obtained by slow evaporation of a solution in THF (yield 71%; m.p. 375–377 K).
Refinement
Crystal data, data collection and structure . H atoms were included in calculated positions and treated as riding atoms: C—H = 0.96–0.97 Å with Uiso(H) = 1.5Ueq(C) for methyl H atoms and 1.2Ueq(C) for other H atoms.
details are summarized in Table 1Structural data
CCDC reference: 1440891
https://doi.org/10.1107/S2414314615021744/sj4001sup1.cif
contains datablocks I, New_Global_Publ_Block. DOI:Supporting information file. DOI: https://doi.org/10.1107/S2414314615021744/sj4001Isup2.cml
Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314615021744/sj4001Isup2.hkl
Data collection: X-AREA (Stoe & Cie, 2009); cell
X-AREA (Stoe & Cie, 2009); data reduction: X-RED32 (Stoe & Cie, 2009); program(s) used to solve structure: SHELXS2014/6 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014/6 (Sheldrick, 2015); molecular graphics: PLATON (Spek, 2009) and Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL2014/6 (Sheldrick, 2015), PLATON (Spek, 2009) and publCIF (Westrip, 2010).C16H20N2O8 | Z = 1 |
Mr = 368.34 | F(000) = 194 |
Triclinic, P1 | Dx = 1.372 Mg m−3 |
a = 5.4194 (8) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 9.0619 (12) Å | Cell parameters from 4119 reflections |
c = 9.4607 (13) Å | θ = 2.2–29.5° |
α = 81.285 (11)° | µ = 0.11 mm−1 |
β = 82.771 (11)° | T = 293 K |
γ = 77.208 (11)° | Plate, colourless |
V = 445.80 (11) Å3 | 0.31 × 0.27 × 0.07 mm |
STOE IPDS 2 diffractometer | 2408 independent reflections |
Radiation source: fine-focus sealed tube | 1414 reflections with I > 2σ(I) |
Plane graphite monochromator | Rint = 0.078 |
φ + ω scans | θmax = 29.2°, θmin = 2.2° |
Absorption correction: multi-scan (MULABS; Spek, 2009) | h = −7→7 |
Tmin = 0.650, Tmax = 1.000 | k = −12→12 |
6815 measured reflections | l = −12→12 |
Refinement on F2 | Hydrogen site location: inferred from neighbouring sites |
Least-squares matrix: full | H-atom parameters constrained |
R[F2 > 2σ(F2)] = 0.049 | w = 1/[σ2(Fo2) + (0.0654P)2] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.124 | (Δ/σ)max < 0.001 |
S = 0.86 | Δρmax = 0.26 e Å−3 |
2408 reflections | Δρmin = −0.21 e Å−3 |
121 parameters | Extinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
0 restraints | Extinction coefficient: 0.054 (10) |
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 | ||
O1 | 0.4462 (2) | −0.06169 (15) | 0.77032 (15) | 0.0584 (4) | |
O2 | 0.1176 (2) | 0.13155 (13) | 0.81276 (11) | 0.0453 (3) | |
O3 | 0.4091 (2) | 0.25124 (15) | 0.54380 (14) | 0.0565 (4) | |
O4 | 0.1520 (2) | 0.36434 (13) | 0.37225 (13) | 0.0484 (3) | |
N1 | 0.0156 (2) | −0.10741 (14) | 0.62316 (14) | 0.0384 (3) | |
C1 | 0.1213 (3) | 0.01462 (17) | 0.60885 (16) | 0.0361 (3) | |
C2 | 0.1086 (3) | 0.12084 (17) | 0.48617 (16) | 0.0367 (3) | |
C3 | 0.2530 (3) | 0.02424 (17) | 0.73804 (17) | 0.0396 (4) | |
C4 | 0.2194 (4) | 0.1491 (2) | 0.94406 (18) | 0.0507 (4) | |
H4B | 0.3871 | 0.1728 | 0.9215 | 0.061* | |
H4A | 0.2333 | 0.0552 | 1.0100 | 0.061* | |
C5 | 0.0414 (5) | 0.2756 (2) | 1.0102 (2) | 0.0679 (6) | |
H5A | −0.1260 | 0.2537 | 1.0266 | 0.102* | |
H5B | 0.0379 | 0.3691 | 0.9466 | 0.102* | |
H5C | 0.0975 | 0.2855 | 1.0999 | 0.102* | |
C6 | 0.2424 (3) | 0.25202 (18) | 0.47080 (17) | 0.0406 (4) | |
C7 | 0.2689 (4) | 0.4982 (2) | 0.3480 (2) | 0.0534 (4) | |
H7A | 0.3113 | 0.5185 | 0.4388 | 0.064* | |
H7B | 0.1485 | 0.5865 | 0.3092 | 0.064* | |
C8 | 0.5034 (4) | 0.4738 (3) | 0.2464 (2) | 0.0704 (6) | |
H8A | 0.4633 | 0.4482 | 0.1583 | 0.106* | |
H8B | 0.6282 | 0.3920 | 0.2884 | 0.106* | |
H8C | 0.5696 | 0.5655 | 0.2270 | 0.106* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0437 (7) | 0.0671 (8) | 0.0647 (8) | 0.0053 (6) | −0.0225 (6) | −0.0197 (6) |
O2 | 0.0438 (6) | 0.0549 (6) | 0.0382 (6) | −0.0040 (5) | −0.0117 (5) | −0.0120 (5) |
O3 | 0.0576 (7) | 0.0670 (8) | 0.0542 (8) | −0.0311 (6) | −0.0183 (6) | 0.0004 (6) |
O4 | 0.0471 (6) | 0.0465 (6) | 0.0540 (7) | −0.0166 (5) | −0.0101 (5) | 0.0001 (5) |
N1 | 0.0335 (6) | 0.0453 (7) | 0.0377 (7) | −0.0098 (6) | −0.0046 (5) | −0.0062 (5) |
C1 | 0.0289 (7) | 0.0439 (8) | 0.0364 (8) | −0.0067 (6) | −0.0028 (6) | −0.0092 (6) |
C2 | 0.0304 (7) | 0.0430 (8) | 0.0381 (8) | −0.0088 (6) | −0.0026 (6) | −0.0089 (6) |
C3 | 0.0359 (8) | 0.0454 (8) | 0.0398 (8) | −0.0111 (7) | −0.0059 (6) | −0.0066 (7) |
C4 | 0.0603 (11) | 0.0575 (10) | 0.0386 (9) | −0.0127 (9) | −0.0153 (8) | −0.0101 (7) |
C5 | 0.0869 (15) | 0.0707 (12) | 0.0470 (11) | −0.0080 (11) | −0.0073 (10) | −0.0220 (9) |
C6 | 0.0380 (8) | 0.0488 (9) | 0.0373 (8) | −0.0135 (7) | −0.0018 (6) | −0.0078 (7) |
C7 | 0.0575 (11) | 0.0459 (9) | 0.0594 (11) | −0.0184 (8) | −0.0047 (8) | −0.0042 (8) |
C8 | 0.0699 (13) | 0.0713 (13) | 0.0711 (14) | −0.0281 (11) | 0.0059 (11) | −0.0024 (11) |
O1—C3 | 1.2012 (18) | C4—C5 | 1.487 (3) |
O2—C3 | 1.3212 (19) | C4—H4B | 0.9700 |
O2—C4 | 1.4642 (18) | C4—H4A | 0.9700 |
O3—C6 | 1.2026 (19) | C5—H5A | 0.9600 |
O4—C6 | 1.324 (2) | C5—H5B | 0.9600 |
O4—C7 | 1.465 (2) | C5—H5C | 0.9600 |
N1—C1 | 1.3359 (19) | C7—C8 | 1.490 (3) |
N1—C2i | 1.3370 (19) | C7—H7A | 0.9700 |
C1—C2 | 1.389 (2) | C7—H7B | 0.9700 |
C1—C3 | 1.513 (2) | C8—H8A | 0.9600 |
C2—N1i | 1.3370 (19) | C8—H8B | 0.9600 |
C2—C6 | 1.504 (2) | C8—H8C | 0.9600 |
C3—O2—C4 | 116.24 (12) | H5A—C5—H5B | 109.5 |
C6—O4—C7 | 117.08 (13) | C4—C5—H5C | 109.5 |
C1—N1—C2i | 116.40 (13) | H5A—C5—H5C | 109.5 |
N1—C1—C2 | 122.26 (13) | H5B—C5—H5C | 109.5 |
N1—C1—C3 | 113.45 (13) | O3—C6—O4 | 125.77 (15) |
C2—C1—C3 | 124.29 (13) | O3—C6—C2 | 121.82 (15) |
N1i—C2—C1 | 121.33 (13) | O4—C6—C2 | 112.39 (13) |
N1i—C2—C6 | 118.01 (14) | O4—C7—C8 | 111.08 (15) |
C1—C2—C6 | 120.63 (13) | O4—C7—H7A | 109.4 |
O1—C3—O2 | 125.92 (15) | C8—C7—H7A | 109.4 |
O1—C3—C1 | 123.30 (14) | O4—C7—H7B | 109.4 |
O2—C3—C1 | 110.63 (12) | C8—C7—H7B | 109.4 |
O2—C4—C5 | 107.54 (15) | H7A—C7—H7B | 108.0 |
O2—C4—H4B | 110.2 | C7—C8—H8A | 109.5 |
C5—C4—H4B | 110.2 | C7—C8—H8B | 109.5 |
O2—C4—H4A | 110.2 | H8A—C8—H8B | 109.5 |
C5—C4—H4A | 110.2 | C7—C8—H8C | 109.5 |
H4B—C4—H4A | 108.5 | H8A—C8—H8C | 109.5 |
C4—C5—H5A | 109.5 | H8B—C8—H8C | 109.5 |
C4—C5—H5B | 109.5 | ||
C2i—N1—C1—C2 | −1.3 (2) | N1—C1—C3—O2 | −105.99 (15) |
C2i—N1—C1—C3 | 178.62 (12) | C2—C1—C3—O2 | 73.95 (18) |
N1—C1—C2—N1i | 1.4 (2) | C3—O2—C4—C5 | 179.40 (16) |
C3—C1—C2—N1i | −178.55 (13) | C7—O4—C6—O3 | 1.3 (2) |
N1—C1—C2—C6 | −176.59 (14) | C7—O4—C6—C2 | −179.88 (13) |
C3—C1—C2—C6 | 3.5 (2) | N1i—C2—C6—O3 | −160.17 (15) |
C4—O2—C3—O1 | 2.1 (2) | C1—C2—C6—O3 | 17.9 (2) |
C4—O2—C3—C1 | 177.82 (13) | N1i—C2—C6—O4 | 21.0 (2) |
N1—C1—C3—O1 | 69.8 (2) | C1—C2—C6—O4 | −160.99 (14) |
C2—C1—C3—O1 | −110.23 (19) | C6—O4—C7—C8 | 84.0 (2) |
Symmetry code: (i) −x, −y, −z+1. |
Acknowledgements
We are grateful to the Swiss National Science Foundation and the University of Neuchâtel for financial support.
References
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