organic compounds
2,6-Dibromo-4-nitrobenzonitrile
aDepartment of Chemistry, University of Minnesota, 207 Pleasant St SE, Minneapolis, MN 55455, USA
*Correspondence e-mail: nolan001@umn.edu
Molecules of the title compound, C7H2Br2N2O2, have C2v symmetry and each lie on a twofold axis that bisects the benzene ring and its nitro and cyano substituents. The cyano N atom is bisected by two CN⋯Br contacts, and the nitro O atoms participate in weak C—H⋯O hydrogen bonds. These interactions form a planar sheet structure that stacks about a glide plane. This stacking mode has not been previously reported with cyano-halo-derived sheets of this type.
Keywords: crystal structure; nitrile; CN⋯Br contacts; C—H⋯O hydrogen bonds.
CCDC reference: 1580005
Structure description
The title nitrile (I) is presented as part of an ongoing packing study of 2,6-dihalobenzonitriles. Molecules of (I) have typical geometry (Fig. 1). The major axis of each molecule (connecting N4 and N7) lies on a twofold axis, two orthogonal mirror planes, and a glide plane. Thus, molecules have C2v and are planar. The cyano groups are bisected by two symmetry-related C7≡N7⋯Br2 contacts (Table 1), forming ribbons of R22(10) inversion dimers along [001]. Adjacent ribbons are related by an [010] translation, giving a planar sheet structure parallel to (100) (Fig. 2a). This sheet is similar to those reported for 2,4,6-tribromobenzonitrile (II) (Fig. 2b; Britton et al., 2016) and 2,6-dibromo-4-chlorobenzonitrile (III), (Fig. 2c; Britton, 2005). The relative displacement of molecules in the different sheets is consistent with the geometries of the 4-substituents. In (II) and (III), there are no short contacts between adjacent ribbons. By contrast, adjacent ribbons in (I) are connected by weak C3—H3A⋯O1 hydrogen bonds that form chains of R22(10) inversion dimers along [001], informally mirroring the CN⋯Br contacts (Table 1). In the crystal of (I), sheets stack about glide planes (Fig. 3a), a stacking mode not yet observed in this series. Three of (II) were reported with combinations of centric (Fig. 3b) and translational stacking. Crystals of (III) had only translational (Fig. 3c) stacking.
Synthesis and crystallization
4-Nitroaniline (2.57 g; Acros Organics Co., No. 12837) was brominated (Br2, 2.1 ml) in acetic acid (100 ml) at 350 K for 6 h. The resulting mixture was cooled to room temperature. A precipitate was collected by filtration, and then neutralized in a mixture of saturated aqueous NaHSO3 (20 ml) and Na2CO3 (100 ml), water (50 ml), and ethyl acetate (300 ml). The organic portion was concentrated on a rotary evaporator, and then recrystallized from chloroform, giving 2,6-dibromo-4-nitroaniline as yellow needles [84% yield, m.p. 480–481 K (lit. 476–477 K; Podgoršek et al., 2009)]. A portion (570 mg) was cyanated according to the Sandmeyer procedure described by Britton et al. (2016), giving (I) as an off-white powder (35% yield, m.p. 466–467 K). 1H NMR (400 MHz, DMSO-d6) δ 8.68 (s, H3A); 13C NMR (101 MHz, DMSO-d6) δ 150.0 (C4), 127.3 (C2), 126.8 (C3), 122.9 (C1), 115.5 (C7); IR (KBr, cm−1) 3098, 2232, 1525, 1345, 1278, 1095, 903, 783, 751, 621. Crystals were prepared by slow evaporation of a solution in chloroform, followed by decantation, and then washing with pentane.
Refinement
Crystal data, data collection, and structure .
details are summarized in Table 2Structural data
CCDC reference: 1580005
https://doi.org/10.1107/S2414314617016170/sj4146sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314617016170/sj4146Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2414314617016170/sj4146Isup3.cml
Data collection: APEX3 (Bruker, 2012); cell
SAINT (Bruker, 2012); data reduction: SAINT (Bruker, 2012); program(s) used to solve structure: SHELXT2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: publCIF (Westrip, 2010).C7H2Br2N2O2 | Dx = 2.309 Mg m−3 |
Mr = 305.93 | Mo Kα radiation, λ = 0.71073 Å |
Orthorhombic, Cmcm | Cell parameters from 2992 reflections |
a = 6.4256 (2) Å | θ = 3.3–36.1° |
b = 12.3231 (5) Å | µ = 9.18 mm−1 |
c = 11.1117 (4) Å | T = 100 K |
V = 879.86 (6) Å3 | Square bipyramid, colorless |
Z = 4 | 0.22 × 0.15 × 0.11 mm |
F(000) = 576 |
Bruker VENTURE PHOTON-II diffractometer | 1060 reflections with I > 2σ(I) |
Radiation source: micro-focus | Rint = 0.027 |
φ and ω scans | θmax = 36.4°, θmin = 3.3° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −10→10 |
Tmin = 0.249, Tmax = 0.344 | k = −20→20 |
10626 measured reflections | l = −18→18 |
1195 independent reflections |
Refinement on F2 | Hydrogen site location: inferred from neighbouring sites |
Least-squares matrix: full | H-atom parameters constrained |
R[F2 > 2σ(F2)] = 0.014 | w = 1/[σ2(Fo2) + (0.0108P)2 + 0.7137P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.035 | (Δ/σ)max = 0.001 |
S = 1.08 | Δρmax = 0.64 e Å−3 |
1195 reflections | Δρmin = −0.43 e Å−3 |
46 parameters | Extinction correction: SHELXL2014 (Sheldrick, 2015b), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
0 restraints | Extinction coefficient: 0.0055 (4) |
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 | ||
Br2 | 0.5000 | 0.83929 (2) | 0.49434 (2) | 0.01475 (5) | |
O1 | 0.5000 | 0.43194 (8) | 0.65277 (9) | 0.0238 (2) | |
N4 | 0.5000 | 0.47860 (12) | 0.7500 | 0.0148 (3) | |
N7 | 0.5000 | 1.03098 (14) | 0.7500 | 0.0193 (3) | |
C1 | 0.5000 | 0.82086 (13) | 0.7500 | 0.0118 (3) | |
C2 | 0.5000 | 0.76354 (9) | 0.64089 (10) | 0.01227 (19) | |
C3 | 0.5000 | 0.65122 (9) | 0.63981 (10) | 0.01287 (19) | |
H3A | 0.5000 | 0.6119 | 0.5663 | 0.015* | |
C4 | 0.5000 | 0.59809 (13) | 0.7500 | 0.0120 (3) | |
C7 | 0.5000 | 0.93761 (15) | 0.7500 | 0.0146 (3) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Br2 | 0.01902 (7) | 0.01452 (6) | 0.01072 (6) | 0.000 | 0.000 | 0.00282 (4) |
O1 | 0.0424 (6) | 0.0139 (4) | 0.0150 (4) | 0.000 | 0.000 | −0.0038 (3) |
N4 | 0.0189 (6) | 0.0118 (6) | 0.0136 (6) | 0.000 | 0.000 | 0.000 |
N7 | 0.0246 (8) | 0.0154 (6) | 0.0178 (6) | 0.000 | 0.000 | 0.000 |
C1 | 0.0124 (6) | 0.0099 (6) | 0.0130 (6) | 0.000 | 0.000 | 0.000 |
C2 | 0.0140 (4) | 0.0128 (4) | 0.0100 (4) | 0.000 | 0.000 | 0.0010 (3) |
C3 | 0.0153 (5) | 0.0128 (5) | 0.0105 (4) | 0.000 | 0.000 | −0.0002 (3) |
C4 | 0.0142 (6) | 0.0106 (6) | 0.0110 (6) | 0.000 | 0.000 | 0.000 |
C7 | 0.0140 (7) | 0.0167 (7) | 0.0130 (6) | 0.000 | 0.000 | 0.000 |
Br2—C2 | 1.8770 (11) | C1—C2i | 1.4031 (14) |
O1—N4 | 1.2239 (12) | C1—C7 | 1.439 (2) |
N4—O1i | 1.2239 (12) | C2—C3 | 1.3842 (17) |
N4—C4 | 1.473 (2) | C3—C4 | 1.3884 (13) |
N7—C7 | 1.151 (3) | C3—H3A | 0.9500 |
C1—C2 | 1.4031 (14) | C4—C3i | 1.3885 (13) |
O1i—N4—O1 | 123.96 (16) | C1—C2—Br2 | 119.95 (9) |
O1i—N4—C4 | 118.02 (8) | C2—C3—C4 | 117.63 (11) |
O1—N4—C4 | 118.02 (8) | C2—C3—H3A | 121.2 |
C2—C1—C2i | 119.55 (15) | C4—C3—H3A | 121.2 |
C2—C1—C7 | 120.23 (7) | C3—C4—C3i | 123.74 (15) |
C2i—C1—C7 | 120.23 (7) | C3—C4—N4 | 118.13 (7) |
C3—C2—C1 | 120.72 (11) | C3i—C4—N4 | 118.13 (7) |
C3—C2—Br2 | 119.32 (8) | N7—C7—C1 | 180.0 |
C2i—C1—C2—C3 | 0.000 (1) | C2—C3—C4—C3i | 0.000 (1) |
C7—C1—C2—C3 | 180.000 (1) | C2—C3—C4—N4 | 180.000 (1) |
C2i—C1—C2—Br2 | 180.000 (1) | O1i—N4—C4—C3 | 180.000 (1) |
C7—C1—C2—Br2 | 0.000 (1) | O1—N4—C4—C3 | 0.000 (1) |
C1—C2—C3—C4 | 0.000 (1) | O1i—N4—C4—C3i | 0.000 (1) |
Br2—C2—C3—C4 | 180.000 (1) | O1—N4—C4—C3i | 180.000 (1) |
Symmetry code: (i) x, y, −z+3/2. |
A—B···C | A—B | B···C | A···C | A—B···C |
C7≡N7···Br2i | 1.151 (3) | 3.1508 (9) | 3.8640 (1) | 120.49 (3) |
C3—H3A···O1ii | 0.95 | 2.493 | 3.409 (2) | 161.82 |
Symmetry codes: (i) -x + 1, -y + 2, -z + 1; (ii) x, -y + 1, -z + 1. |
Acknowledgements
The authors thank Victor G. Young, Jr (X-Ray Crystallographic Laboratory, University of Minnesota) for assistance with the crystallographic determination, the Wayland E. Noland Research Fellowship Fund at the University of Minnesota Foundation for generous financial support of this project, and Doyle Britton (deceased July 7, 2015) for providing the basis of this project.
References
Britton, D. (2005). Acta Cryst. E61, o1726–o1727. Web of Science CSD CrossRef IUCr Journals Google Scholar
Britton, D., Noland, W. E. & Tritch, K. J. (2016). Acta Cryst. E72, 178–183. CSD CrossRef IUCr Journals Google Scholar
Bruker (2012). APEX2 and SAINT. Bruker AXS, Inc., Madison, Wisconsin, USA. Google Scholar
Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466–470. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Podgoršek, A., Stavber, S., Zupan, M. & Iskra, J. (2009). Tetrahedron, 65, 4429–4439. Google Scholar
Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925. Web of Science CrossRef CAS IUCr Journals Google Scholar
This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.