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The crystal packing of the title compound, C10H8BrN3O2, is determined mainly by relatively strong bifurcated C—Br...O halogen–nitro bonds. Both O atoms are involved in this interaction in an almost symmetrical manner and the difference [0.078 (3) Å] between the Br...O contact lengths is one of the smallest found in similar compounds. Halogen bonds and weak hydrogen bonds connect mol­ecules into layers which are stacked along the [100] direction.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S010827010400650X/fg1748sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S010827010400650X/fg1748Isup2.hkl
Contains datablock I

CCDC reference: 241232

Comment top

The attractive interactions between organic halogen and nitro-group O atoms have been identified as robust and effective supramolecular synthons, as defined by Desiraju (1995). Allen et al. (1997) carried out an analysis of the Cambridge Structural Database (CSD) and an ab initio molecular study, which showed that the degree of interpenetration of the X and O atoms increases in the order Cl < Br < I, and that the C—X···O angle becomes closer to 180° as the X···O separation decreases. This is an example of a wider group of so-called 'halogen bonds' (for a recent review see, for example, Metrangolo et al., 2003), the attractive interaction between organic halogen and atoms possessing electron lone pairs. This interaction is directional and can compete successfully with hydrogen bonds for the leading role in driving self-assembly processes (Corradi et al., 2000). There are examples of the presence of halogen bonds in liquid crystals (Nguyen et al., 2004), in solution (Wash et al., 1999) and in a gas phase (Legon, 1998).

In the case of the X···O(nitro) halogen bond, three different motifs were identified (Desiraju et al., 1993). The first is the symmetrical bifurcated motif, in which the two X···O distances are almost equal and X effectively interacts with both O atoms. The second is the asymmetrical bifurcated motif, in which one of the X···O distances is too long for any interaction, but the X atom still approaches the bonded O atoms trans with respect to C—N bond. The third is the mono-coordinated motif, when the X···O contact is cis to the C—N bond. Allen et al. (1997) found that the tendency to form the bifurcated motifs increases in order Cl < Br < I.

Against this background, and as part of a wider study of weak interactions in 4-nitroimidazole derivatives, the crystal structure of 1-(4'-bromophenyl)-2-methyl-4-nitroimidazole, (I), has been determined and the results are presented here. \sch

The crystal packing of (I) could, in principle, be influenced by at least three specific interactions, namely ππ stacking of planar aromatic fragments, weak C—H···O(N) hydrogen bonds and Br···O halogen bonds. All three kinds of interactions have been found in similar compounds (e.g. 1-aryl-4-nitro-5-methylimidazole derivatives; Kubicki, 2004).

Fig. 1 shows the molecule of (I), which consists of three planar fragments: the phenyl ring [maximum deviation from the least-squares plane 0.007 (3) Å For which atom?], the imidazole ring [maximum deviation 0.006 (2) Å For which atom?] and the nitro group. The dihedral angle between the phenyl and imidazole ring planes is 56.4 (1)° and the nitro group is almost parallel to the imidazole plane [1.8 (6)°]. The bond lengths and angles are typical.

There is an interesting asymmetry in the geometry of the nitro group. The N—O bond cis to atom N3 (N4—O41) is slightly shorter [by 0.013 (4) Å] than the trans bond (N4—O42). This asymmetry is accompanied by a difference in the C—N—O angles, with C4—N4—O41 being 2.3 (3)° greater than C4—N4—O42. Exactly the reverse situation was found in the series of 1-aryl-4-nitro-5-methylimidazole derivatives (Kubicki, 2004). A CSD (Version?; Allen, 2002) analysis shows that it can be regarded as a strong tendency: asymmetry similar to that in (I) is observed in simple 1-substituted-4-nitro-imidazoles, without the substituent at the 5-position, while in case of 5-substituted compounds, the situation is reversed, with C4—N4—O42-type angles being greater than C4—N4—O41.

The crystal structure of (I) is determined by relatively short Br···O halogen bonds, of the first type mentioned above, i.e. almost symmetrical and bifurcated. The Br···O41i distance is 3.364 (3) Å and Br···O42i is 3.286 (3) Å [symmetry code: (i) 3/2 − x, 1 − y, z − 1/2]. The difference between these contacts, 0.078 (3) Å, is one of the smallest found in similar compounds. In the January 2004 version of the CSD, there are 111 compounds which have both aromatic Br and nitro groups (only organics, no errors, coordinates available, duplicate entries excluded). In 34 (ca 31%) of the structures, the Br···O contact is shorter than the sum of the van der Waals radii; when the limit is set at the sum of the van der Waals radii plus 0.2 Å, the fraction of structures fulfilling this condition grows to almost 43% (47 structures, 66 fragments). Only for 12 of these cases is the difference between Br···O distances less than 0.3 Å. The smallest difference, of 0.072 Å, was found in the structure of 1-acetyl-5-bromo-7-nitroindoline (Moreno et al., 1998), and the present case provides the second most symmetrical Br···O(nitro) approach.

This CSD analysis confirms the directionality of this type of interaction and the tendency towards more linear C—Br···O angles as the Br···O separation decreases. In particular, for Br···O distances shorter than 3.33 Å there are no C—Br···O angles smaller than 139°. The case of (I) follows this tendency: the C—Br···O41 angle is 158.5° and C—Br···O42 157.3°.

These halogen bonds, together with weak C—H···O and C—H···N contacts (Table 2 and Fig. 2), connect the molecules of (I) into layers. Using graph-set notation (Etter et al., 1990; Bernstein et al., 1995), there are first-order chains, C(10)[R21(4)], C(4) and C(7), and more interesting higher-order rings, R22(9) and R44(18). Following, for example, Bryant et al. (1998), we have taken the Br···O halogen bonds as pseudo-hydrogen bonds, with Br as the donor and O as the acceptor. These layers are stacked on top of one another, and there are only weak C—H···O contacts between the neighbouring layers, as the distance between the ring planes is too long for a significant stacking interaction (4.15 Å).

Table 2. Geometry of hydrogen bonds and short contacts

Experimental top

The method of synthesis of compound (I) was as described elsewhere by Suwiński & Świerczek (1996). Crystals for data collection were grown from a methanol solution by slow evaporation.

Refinement top

Please give brief details of H-atom constraints.

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2002); cell refinement: CrysAlis CCD; data reduction: CrysAlis RED (Oxford Diffraction, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: Stereochemical Workstation (Siemens, 1989).

Figures top
[Figure 1] Fig. 1. A view of the molecule of (I), with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are depicted as small spheres of arbitrary radii.
[Figure 2] Fig. 2. The layer of molecules of (I), as seen along the [100] direction. Halogen bonds and weak hydrogen bonds are drawn as dashed lines. Symmetry codes: (i) 3/2 − x, 1 − y, z − 1/2; (ii) 3/2 − x, 1 − y, 1/2 + z; (iii) 1 − x, 1/2 + y, 3/2 − z; (iv) x − 1/2, 3/2 − y, 1 − z; (v) 1 − x, y − 1/2, 3/2 − z; (vi) x − 1/2, 1/2 − y, 1 − z.
1-(4-Bromophenyl)-2-methyl-4-nitro-1H-imidazole top
Crystal data top
C10H8BrN3O2F(000) = 560
Mr = 282.10Dx = 1.790 Mg m3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 2848 reflections
a = 4.1443 (5) Åθ = 3–18°
b = 10.4459 (8) ŵ = 3.92 mm1
c = 24.1758 (19) ÅT = 100 K
V = 1046.59 (17) Å3Prism, colourless
Z = 40.6 × 0.15 × 0.1 mm
Data collection top
KUMA KM-4 CCD four-circle
diffractometer
2308 independent reflections
Radiation source: fine-focus sealed tube1977 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.096
ω scansθmax = 29.2°, θmin = 4.7°
Absorption correction: multi-scan
(SORTAV; Blessing, 1989)
h = 53
Tmin = 0.389, Tmax = 0.676k = 1313
4145 measured reflectionsl = 3115
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.040H-atom parameters constrained
wR(F2) = 0.097 w = 1/[σ2(Fo2) + (0.0539P)2 + 0.104P]
where P = (Fo2 + 2Fc2)/3
S = 1.10(Δ/σ)max = 0.001
2308 reflectionsΔρmax = 0.73 e Å3
146 parametersΔρmin = 0.95 e Å3
0 restraintsAbsolute structure: Flack (1983), with x Friedel pairs
Primary atom site location: structure-invariant direct methodsAbsolute structure parameter: 0.018 (15)
Crystal data top
C10H8BrN3O2V = 1046.59 (17) Å3
Mr = 282.10Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 4.1443 (5) ŵ = 3.92 mm1
b = 10.4459 (8) ÅT = 100 K
c = 24.1758 (19) Å0.6 × 0.15 × 0.1 mm
Data collection top
KUMA KM-4 CCD four-circle
diffractometer
2308 independent reflections
Absorption correction: multi-scan
(SORTAV; Blessing, 1989)
1977 reflections with I > 2σ(I)
Tmin = 0.389, Tmax = 0.676Rint = 0.096
4145 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.040H-atom parameters constrained
wR(F2) = 0.097Δρmax = 0.73 e Å3
S = 1.10Δρmin = 0.95 e Å3
2308 reflectionsAbsolute structure: Flack (1983), with x Friedel pairs
146 parametersAbsolute structure parameter: 0.018 (15)
0 restraints
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
xyzUiso*/Ueq
N10.8048 (9)0.6622 (3)0.67555 (12)0.0137 (7)
C110.8719 (10)0.6033 (4)0.62277 (13)0.0124 (8)
C121.0078 (10)0.4834 (4)0.62080 (15)0.0153 (9)
H121.05840.43980.65420.018*
C131.0716 (11)0.4255 (4)0.57008 (15)0.0174 (8)
H131.16520.34260.56850.021*
C140.9959 (10)0.4914 (4)0.52152 (15)0.0148 (9)
Br141.09105 (11)0.41611 (4)0.451856 (15)0.02178 (13)
C150.8543 (10)0.6117 (4)0.52344 (15)0.0185 (9)
H150.79960.65470.49010.022*
C160.7923 (11)0.6695 (4)0.57435 (15)0.0165 (8)
H160.69780.75220.57610.020*
C20.9153 (11)0.7801 (4)0.69409 (14)0.0142 (8)
C211.1314 (11)0.8655 (4)0.66054 (15)0.0156 (8)
H21A0.99980.91920.63610.020*
H21B1.27770.81290.63820.020*
H21C1.25770.92020.68540.020*
N30.8066 (8)0.8049 (3)0.74438 (12)0.0137 (7)
C40.6262 (10)0.7002 (4)0.75764 (14)0.0109 (7)
N40.4561 (9)0.6931 (3)0.80942 (12)0.0146 (7)
O410.4836 (7)0.7810 (3)0.84256 (11)0.0205 (7)
O420.2918 (8)0.5960 (3)0.81753 (11)0.0214 (7)
C50.6208 (11)0.6093 (4)0.71680 (13)0.0127 (8)
H50.51470.52870.71700.015*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0142 (19)0.0160 (17)0.0109 (13)0.0005 (14)0.0001 (12)0.0009 (12)
C110.014 (2)0.0130 (18)0.0104 (14)0.0002 (17)0.0015 (13)0.0007 (13)
C120.018 (2)0.0151 (19)0.0126 (16)0.0032 (16)0.0028 (14)0.0015 (14)
C130.018 (2)0.0181 (19)0.0166 (16)0.001 (2)0.0000 (16)0.0049 (15)
C140.017 (2)0.0158 (19)0.0119 (16)0.0001 (15)0.0015 (13)0.0063 (14)
Br140.0243 (2)0.0289 (2)0.01213 (17)0.0013 (2)0.00213 (16)0.00668 (16)
C150.016 (2)0.028 (2)0.0113 (16)0.0005 (18)0.0002 (14)0.0041 (15)
C160.015 (2)0.021 (2)0.0139 (18)0.0037 (18)0.0015 (15)0.0020 (16)
C20.013 (2)0.0187 (19)0.0107 (15)0.007 (2)0.0018 (16)0.0000 (13)
C210.014 (2)0.0153 (18)0.0173 (17)0.0016 (18)0.0034 (15)0.0025 (14)
N30.0129 (18)0.0163 (17)0.0119 (14)0.0008 (14)0.0013 (12)0.0009 (12)
C40.014 (2)0.0087 (17)0.0102 (15)0.0035 (17)0.0009 (14)0.0006 (12)
N40.0156 (19)0.0175 (17)0.0107 (14)0.0021 (15)0.0015 (13)0.0021 (12)
O410.0276 (19)0.0197 (15)0.0142 (13)0.0034 (13)0.0022 (11)0.0065 (11)
O420.0264 (17)0.0202 (15)0.0175 (13)0.0076 (15)0.0044 (11)0.0003 (12)
C50.015 (2)0.0138 (18)0.0096 (14)0.0021 (17)0.0011 (14)0.0019 (12)
Geometric parameters (Å, º) top
N1—C51.372 (5)C16—H160.9500
N1—C21.389 (5)C2—N31.322 (5)
N1—C111.443 (4)C2—C211.502 (6)
C11—C121.375 (5)C21—H21A0.9800
C11—C161.399 (5)C21—H21B0.9800
C12—C131.392 (5)C21—H21C0.9800
C12—H120.9500N3—C41.363 (5)
C13—C141.396 (5)C4—C51.370 (5)
C13—H130.9500C4—N41.439 (5)
C14—C151.388 (6)N4—O411.224 (4)
C14—Br141.900 (4)N4—O421.237 (4)
C15—C161.395 (5)C5—H50.9500
C15—H150.9500
C5—N1—C2107.8 (3)C11—C16—H16120.6
C5—N1—C11125.3 (3)N3—C2—N1111.0 (4)
C2—N1—C11126.9 (3)N3—C2—C21125.7 (4)
C12—C11—C16121.2 (3)N1—C2—C21123.3 (3)
C12—C11—N1119.9 (3)C2—C21—H21A109.5
C16—C11—N1118.9 (3)C2—C21—H21B109.5
C11—C12—C13120.3 (4)H21A—C21—H21B109.5
C11—C12—H12119.9C2—C21—H21C109.5
C13—C12—H12119.9H21A—C21—H21C109.5
C12—C13—C14118.9 (4)H21B—C21—H21C109.5
C12—C13—H13120.5C2—N3—C4104.3 (3)
C14—C13—H13120.5N3—C4—C5113.3 (3)
C15—C14—C13120.9 (3)N3—C4—N4121.0 (3)
C15—C14—Br14119.5 (3)C5—C4—N4125.7 (4)
C13—C14—Br14119.6 (3)O41—N4—O42124.2 (3)
C14—C15—C16119.9 (3)O41—N4—C4119.0 (3)
C14—C15—H15120.0O42—N4—C4116.7 (3)
C16—C15—H15120.0C4—C5—N1103.6 (3)
C15—C16—C11118.8 (4)C4—C5—H5128.2
C15—C16—H16120.6N1—C5—H5128.2
C5—N1—C11—C1255.4 (6)C11—N1—C2—N3179.7 (4)
C2—N1—C11—C12123.8 (5)C5—N1—C2—C21178.7 (4)
C5—N1—C11—C16123.7 (4)C11—N1—C2—C210.6 (6)
C2—N1—C11—C1657.1 (6)N1—C2—N3—C40.3 (4)
C16—C11—C12—C130.5 (7)C21—C2—N3—C4179.3 (4)
N1—C11—C12—C13179.6 (4)C2—N3—C4—C50.5 (5)
C11—C12—C13—C140.1 (6)C2—N3—C4—N4177.9 (4)
C12—C13—C14—C151.1 (7)N3—C4—N4—O412.4 (6)
C12—C13—C14—Br14178.4 (3)C5—C4—N4—O41179.5 (4)
C13—C14—C15—C161.4 (6)N3—C4—N4—O42178.3 (3)
Br14—C14—C15—C16178.1 (3)C5—C4—N4—O420.2 (6)
C14—C15—C16—C110.7 (6)N3—C4—C5—N11.0 (5)
C12—C11—C16—C150.2 (7)N4—C4—C5—N1177.2 (4)
N1—C11—C16—C15179.3 (4)C2—N1—C5—C41.1 (4)
C5—N1—C2—N30.9 (5)C11—N1—C5—C4179.5 (4)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C12—H12···O41i0.952.523.114 (5)121
C21—H21A···O42ii0.982.483.026 (5)115
C21—H21C···O42iii0.982.623.434 (5)141
C5—H5···N3iv0.952.853.759 (5)161
Symmetry codes: (i) x+2, y1/2, z+3/2; (ii) x+1, y+1/2, z+3/2; (iii) x+2, y+1/2, z+3/2; (iv) x+1, y1/2, z+3/2.

Experimental details

Crystal data
Chemical formulaC10H8BrN3O2
Mr282.10
Crystal system, space groupOrthorhombic, P212121
Temperature (K)100
a, b, c (Å)4.1443 (5), 10.4459 (8), 24.1758 (19)
V3)1046.59 (17)
Z4
Radiation typeMo Kα
µ (mm1)3.92
Crystal size (mm)0.6 × 0.15 × 0.1
Data collection
DiffractometerKUMA KM-4 CCD four-circle
diffractometer
Absorption correctionMulti-scan
(SORTAV; Blessing, 1989)
Tmin, Tmax0.389, 0.676
No. of measured, independent and
observed [I > 2σ(I)] reflections
4145, 2308, 1977
Rint0.096
(sin θ/λ)max1)0.685
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.040, 0.097, 1.10
No. of reflections2308
No. of parameters146
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.73, 0.95
Absolute structureFlack (1983), with x Friedel pairs
Absolute structure parameter0.018 (15)

Computer programs: CrysAlis CCD (Oxford Diffraction, 2002), CrysAlis CCD, CrysAlis RED (Oxford Diffraction, 2002), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), Stereochemical Workstation (Siemens, 1989).

Selected geometric parameters (Å, º) top
N1—C51.372 (5)N3—C41.363 (5)
N1—C21.389 (5)C4—N41.439 (5)
N1—C111.443 (4)N4—O411.224 (4)
C14—Br141.900 (4)N4—O421.237 (4)
C2—N31.322 (5)
C5—N1—C2107.8 (3)N3—C4—N4121.0 (3)
C15—C14—C13120.9 (3)C5—C4—N4125.7 (4)
C15—C14—Br14119.5 (3)O41—N4—O42124.2 (3)
C13—C14—Br14119.6 (3)O41—N4—C4119.0 (3)
C2—N3—C4104.3 (3)O42—N4—C4116.7 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C12—H12···O41i0.952.523.114 (5)121
C21—H21A···O42ii0.982.483.026 (5)115
C21—H21C···O42iii0.982.623.434 (5)141
C5—H5···N3iv0.952.853.759 (5)161
Symmetry codes: (i) x+2, y1/2, z+3/2; (ii) x+1, y+1/2, z+3/2; (iii) x+2, y+1/2, z+3/2; (iv) x+1, y1/2, z+3/2.
 

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