In the crystal structure of the title compound, C
4H
4N
2O
2, the pyrazine
N,N′-dioxide molecules are located on centres of inversion. The molecules are stacked in the direction of the crystallographic
a axis and are connected
via C—H
O hydrogen bonding.
Supporting information
CCDC reference: 200770
Key indicators
- Single-crystal X-ray study
- T = 293 K
- Mean (C-C) = 0.002 Å
- R factor = 0.039
- wR factor = 0.106
- Data-to-parameter ratio = 14.5
checkCIF results
No syntax errors found
ADDSYM reports no extra symmetry
Data collection: IPDS Program Package (Stoe & Cie, 1998); cell refinement: IPDS Program Package; data reduction: IPDS Program Package; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP in SHELXTL (Bruker, 1998); software used to prepare material for publication: CIFTAB in SHELXL97.
Pyrazine N,
N'-dioxide
top
Crystal data top
C4H4N2O2 | F(000) = 116 |
Mr = 112.09 | Dx = 1.594 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 3.7376 (6) Å | Cell parameters from 1392 reflections |
b = 11.0011 (18) Å | θ = 4–28° |
c = 5.7184 (9) Å | µ = 0.13 mm−1 |
β = 96.778 (19)° | T = 293 K |
V = 233.48 (6) Å3 | Block, colourless |
Z = 2 | 0.3 × 0.2 × 0.2 mm |
Data collection top
Stoe IPDS diffractometer | 427 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.032 |
Graphite monochromator | θmax = 28.0°, θmin = 4.0° |
φ scans | h = −4→4 |
1450 measured reflections | k = −14→11 |
551 independent reflections | l = −7→7 |
Refinement top
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)] = 0.039 | H-atom parameters constrained |
wR(F2) = 0.106 | w = 1/[σ2(Fo2) + (0.0567P)2 + 0.0228P] where P = (Fo2 + 2Fc2)/3 |
S = 1.07 | (Δ/σ)max < 0.001 |
551 reflections | Δρmax = 0.19 e Å−3 |
38 parameters | Δρmin = −0.14 e Å−3 |
0 restraints | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.41 (9) |
Special details top
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. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
N1 | 0.2159 (3) | 0.42985 (10) | 0.6583 (2) | 0.0419 (4) | |
O1 | 0.4230 (3) | 0.36378 (9) | 0.8052 (2) | 0.0578 (4) | |
C1 | 0.0743 (4) | 0.38407 (12) | 0.4468 (2) | 0.0454 (4) | |
H1 | 0.1242 | 0.3042 | 0.4082 | 0.054* | |
C2 | 0.1397 (4) | 0.54639 (12) | 0.7094 (2) | 0.0445 (4) | |
H2 | 0.2348 | 0.5795 | 0.8531 | 0.053* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
N1 | 0.0458 (6) | 0.0394 (6) | 0.0381 (6) | −0.0046 (4) | −0.0045 (5) | 0.0035 (4) |
O1 | 0.0666 (7) | 0.0471 (6) | 0.0535 (7) | −0.0002 (4) | −0.0192 (5) | 0.0083 (4) |
C1 | 0.0517 (8) | 0.0383 (6) | 0.0440 (8) | −0.0027 (5) | −0.0033 (6) | −0.0039 (5) |
C2 | 0.0510 (7) | 0.0435 (7) | 0.0369 (7) | −0.0057 (5) | −0.0032 (6) | −0.0030 (5) |
Geometric parameters (Å, º) top
N1—O1 | 1.2962 (14) | C1—H1 | 0.9300 |
N1—C2 | 1.3526 (17) | C2—C1i | 1.3617 (19) |
N1—C1 | 1.3582 (17) | C2—H2 | 0.9300 |
C1—C2i | 1.3617 (19) | | |
| | | |
O1—N1—C2 | 121.08 (11) | C2i—C1—H1 | 119.6 |
O1—N1—C1 | 120.61 (12) | N1—C2—C1i | 120.87 (12) |
C2—N1—C1 | 118.30 (11) | N1—C2—H2 | 119.6 |
N1—C1—C2i | 120.83 (13) | C1i—C2—H2 | 119.6 |
N1—C1—H1 | 119.6 | | |
Symmetry code: (i) −x, −y+1, −z+1. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
C1—H1···O1ii | 0.93 | 2.27 | 3.1682 (18) | 162 |
C2—H2···O1iii | 0.93 | 2.29 | 3.2067 (19) | 168 |
Symmetry codes: (ii) x, −y+1/2, z−1/2; (iii) −x+1, −y+1, −z+2. |