1,3-Bis(bromo­meth­yl)-2-nitro­benzene

In the title compound, C₈H₇Br₂NO₂, an inter­mediate for the synthesis of macrocycles, the NO₂ group makes a dihedral angle of 65.07 (19)° with the arene ring, and the bromo­methyl substituents adopt a trans conformation about the ring such that the mol­ecule closely approximates C2 symmetry.

Key indicators

• Single-crystal X-ray study
• T = 185 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.037
• wR factor = 0.083
• Data-to-parameter ratio = 19.1

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600         70

Alert level G
PLAT128_ALERT_4_G Non-standard setting of Space-group P21/c   ....      P21/n

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Derivatives of 1,3-bis(bromomethyl)benzene have been widely used to synthesize macrocycles via S_N2 reactions. For recent examples, see Raatikainen et al., 2008 and Mough et al., 2004.

The crystal structure of the title compound is in comparison with the already reported 1,3-bis(bromomethyl)benzene (II) (Li et al., 2006) and 2,3-bis(bromomethyl)-1-methoxy-4-nitrobenzene (III) (Qin et al., 2005). The nitro group of I is oriented at a dihedral angle of 65.07(0.19)° to the arene ring. The bromomethyl groups (C7/Br1 and C8/Br2) are oriented anti to each other and exhibit almost identical dihedral angles with respect to arene ring carbons atoms (80.34(0.27)° and 80.99(0.28)°, respectively). The molecules therefore closely approximate C2 point group symmetry in the crystal.

Related literature

For related structures, see: Li et al. (2006); Qin et al. (2005). For related compounds, see: Raatikainen et al. (2008); Mough et al. (2004). For the synthesis, see: Boeckmann & Vögtle (1981).

S2. Experimental

The title compound was prepared following the method reported by Boeckmann and Vögtle et al., 1981.

S3. Refinement

The aromatic and methylene H-atoms were positioned geometrically and refined using a riding model with d(C—H) = 0.95 Å, U_iso=1.2U_eq (C) for aromatic 0.99 Å, U_iso = 1.2U_eq (C) for methylene

Electron density synthesis with coefficients Fo—Fc: Highest peak 1.35 at 0.7472 0.2174 0.6981 [ 0.78 A from BR2 ] Deepest hole -1.31 at 0.7372 0.0534 0.6462 [ 0.75 A from BR2 ]

Computing details

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997), PLATON (Spek, 2009) and X-SEED (Barbour, 2001); software used to prepare material for publication: WinGX (Farrugia, 1999) and PLATON (Spek, 2009).

Figures

	Fig. 1. The labelled thermal ellipsoid plot of (I) at the 50% probability level.
	Fig. 2. The unit cell packing diagram of (I) as viewed down the b axis.

1,3-Bis(bromomethyl)-2-nitrobenzene

Crystal data

C8H7Br2NO2	F(000) = 592
Mr = 308.97	Dx = 2.133 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 1024 reflections
a = 7.7837 (13) Å	θ = 2.6–28.0°
b = 7.7573 (13) Å	µ = 8.39 mm^−1
c = 15.938 (3) Å	T = 185 K
β = 90.933 (3)°	Needles, colorless
V = 962.2 (3) Å^3	0.20 × 0.20 × 0.08 mm
Z = 4

Data collection

Bruker SMART 1K diffractometer	2259 independent reflections
Radiation source: fine-focus sealed tube	1812 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.041
ω scan	θmax = 28.0°, θmin = 2.6°
Absorption correction: multi-scan (SADABS; Bruker, 2001)	h = −10→10
Tmin = 0.285, Tmax = 0.553	k = −10→10
8228 measured reflections	l = −21→20

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.037	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.083	H-atom parameters constrained
S = 1.06	w = 1/[σ^2(Fo^2) + (0.0289P)^2 + 1.9462P] where P = (Fo^2 + 2Fc^2)/3
2259 reflections	(Δ/σ)max < 0.001
118 parameters	Δρmax = 1.35 e Å^−3
0 restraints	Δρmin = −1.31 e Å^−3

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. 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 (Ų)

	x	y	z	Uiso*/Ueq
Br1	0.20766 (5)	0.59088 (5)	0.74548 (2)	0.03326 (13)
Br2	0.26732 (6)	0.86865 (6)	0.32665 (3)	0.04186 (15)
C1	0.2474 (4)	0.6504 (4)	0.5246 (2)	0.0211 (7)
N1	0.2391 (4)	0.8324 (4)	0.55227 (19)	0.0245 (7)
C2	0.1776 (4)	0.6087 (4)	0.4461 (2)	0.0203 (7)
C3	0.1891 (5)	0.4378 (5)	0.4212 (2)	0.0238 (8)
H3	0.1450	0.4051	0.3676	0.029*
O1	0.3753 (4)	0.9089 (4)	0.5617 (2)	0.0434 (8)
C6	0.3228 (4)	0.5301 (5)	0.5786 (2)	0.0205 (7)
C5	0.3295 (5)	0.3604 (5)	0.5504 (2)	0.0249 (8)
H5	0.3807	0.2750	0.5855	0.030*
C7	0.3935 (5)	0.5748 (5)	0.6637 (2)	0.0281 (8)
H7A	0.4550	0.6864	0.6610	0.034*
H7B	0.4768	0.4854	0.6820	0.034*
O2	0.0993 (4)	0.8953 (4)	0.5634 (2)	0.0426 (8)
C4	0.2638 (5)	0.3131 (5)	0.4729 (2)	0.0260 (8)
H4	0.2695	0.1965	0.4550	0.031*
C8	0.0943 (5)	0.7371 (5)	0.3889 (2)	0.0259 (8)
H8A	0.0239	0.8174	0.4222	0.031*
H8B	0.0170	0.6766	0.3487	0.031*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0391 (2)	0.0396 (2)	0.0212 (2)	−0.00245 (18)	0.00494 (16)	−0.00610 (16)
Br2	0.0346 (2)	0.0541 (3)	0.0370 (3)	−0.0017 (2)	0.00213 (18)	0.0232 (2)
C1	0.0198 (17)	0.0187 (17)	0.0247 (18)	−0.0006 (14)	0.0027 (14)	−0.0005 (14)
N1	0.0324 (18)	0.0223 (16)	0.0188 (15)	0.0027 (13)	−0.0022 (13)	0.0000 (12)
C2	0.0161 (16)	0.0231 (18)	0.0218 (18)	−0.0003 (14)	0.0033 (14)	0.0018 (14)
C3	0.0227 (18)	0.030 (2)	0.0190 (18)	−0.0043 (15)	0.0030 (15)	−0.0041 (15)
O1	0.0381 (17)	0.0343 (16)	0.058 (2)	−0.0126 (14)	0.0095 (15)	−0.0141 (15)
C6	0.0153 (16)	0.0287 (18)	0.0175 (17)	−0.0005 (14)	0.0020 (14)	0.0005 (14)
C5	0.0254 (19)	0.0218 (17)	0.028 (2)	0.0038 (15)	0.0060 (16)	0.0076 (15)
C7	0.0247 (19)	0.038 (2)	0.0215 (19)	0.0002 (16)	−0.0013 (15)	0.0014 (16)
O2	0.0310 (16)	0.0359 (16)	0.061 (2)	0.0146 (13)	−0.0064 (15)	−0.0158 (15)
C4	0.0258 (19)	0.0215 (18)	0.031 (2)	−0.0022 (15)	0.0074 (16)	−0.0021 (15)
C8	0.0228 (19)	0.031 (2)	0.0236 (19)	−0.0007 (16)	0.0001 (15)	0.0058 (15)

Geometric parameters (Å, º)

Br1—C7	1.967 (4)	C3—H3	0.9500
Br2—C8	1.971 (4)	C6—C5	1.392 (5)
C1—C6	1.392 (5)	C6—C7	1.497 (5)
C1—C2	1.395 (5)	C5—C4	1.379 (5)
C1—N1	1.480 (5)	C5—H5	0.9500
N1—O2	1.209 (4)	C7—H7A	0.9900
N1—O1	1.222 (4)	C7—H7B	0.9900
C2—C3	1.387 (5)	C4—H4	0.9500
C2—C8	1.491 (5)	C8—H8A	0.9900
C3—C4	1.392 (5)	C8—H8B	0.9900
C6—C1—C2	123.6 (3)	C6—C5—H5	119.2
C6—C1—N1	118.4 (3)	C6—C7—Br1	110.6 (2)
C2—C1—N1	118.0 (3)	C6—C7—H7A	109.5
O2—N1—O1	124.5 (3)	Br1—C7—H7A	109.5
O2—N1—C1	118.2 (3)	C6—C7—H7B	109.5
O1—N1—C1	117.3 (3)	Br1—C7—H7B	109.5
C3—C2—C1	116.9 (3)	H7A—C7—H7B	108.1
C3—C2—C8	119.6 (3)	C5—C4—C3	119.4 (3)
C1—C2—C8	123.5 (3)	C5—C4—H4	120.3
C2—C3—C4	121.6 (3)	C3—C4—H4	120.3
C2—C3—H3	119.2	C2—C8—Br2	111.1 (2)
C4—C3—H3	119.2	C2—C8—H8A	109.4
C1—C6—C5	116.9 (3)	Br2—C8—H8A	109.4
C1—C6—C7	123.3 (3)	C2—C8—H8B	109.4
C5—C6—C7	119.7 (3)	Br2—C8—H8B	109.4
C4—C5—C6	121.7 (3)	H8A—C8—H8B	108.0
C4—C5—H5	119.2
C6—C1—N1—O2	−115.0 (4)	N1—C1—C6—C5	−179.6 (3)
C2—C1—N1—O2	64.5 (5)	C2—C1—C6—C7	−178.4 (3)
C6—C1—N1—O1	65.5 (5)	N1—C1—C6—C7	1.0 (5)
C2—C1—N1—O1	−115.1 (4)	C1—C6—C5—C4	−0.3 (5)
C6—C1—C2—C3	−1.5 (5)	C7—C6—C5—C4	179.1 (3)
N1—C1—C2—C3	179.1 (3)	C1—C6—C7—Br1	80.1 (4)
C6—C1—C2—C8	179.0 (3)	C5—C6—C7—Br1	−99.3 (3)
N1—C1—C2—C8	−0.4 (5)	C6—C5—C4—C3	0.2 (5)
C1—C2—C3—C4	1.2 (5)	C2—C3—C4—C5	−0.6 (5)
C8—C2—C3—C4	−179.2 (3)	C3—C2—C8—Br2	−98.9 (3)
C2—C1—C6—C5	1.0 (5)	C1—C2—C8—Br2	80.6 (4)