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CHEMISTRY
ISSN: 2053-2296

2-Bromo-1,3-bis­­(bromo­meth­yl)­benzene, with Z′ = 1.5: whole-mol­ecule disorder of one of the two independent mol­ecules

CROSSMARK_Color_square_no_text.svg

aDepartment of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, Scotland
*Correspondence e-mail: w.harrison@abdn.ac.uk

(Received 10 May 2006; accepted 12 May 2006; online 15 June 2006)

The title compound, C8H7Br3, possesses normal geometrical parameters. There are two independent mol­ecules; one shows whole-mol­ecule disorder with respect to an inversion-symmetry-generated partner, while the other is undisordered. This results in the unusual situation of Z′ = 1.5 and Z = 6 for a monoclinic crystal system. The undisordered mol­ecule inter­acts with its neighbours by way of ππ stacking.

Comment

The title compound, (I)[link], prepared earlier by Newcombe et al. (1977[Newcombe, M., Moore, S. S. & Cram, D. J. (1977). J. Am. Chem. Soc. 99, 6405-6410.]), was obtained during our ongoing studies to determine the philicity of aryl radicals by competitive cyclization reactions (Kirsop et al., 2004a[Kirsop, P., Storey, J. M. D. & Harrison, W. T. A. (2004a). Acta Cryst. C60, o353-o355.],b[Kirsop, P., Storey, J. M. D. & Harrison, W. T. A. (2004b). Acta Cryst. E60, o222-o224.],c[Kirsop, P., Storey, J. M. D. & Harrison, W. T. A. (2004c). Acta Cryst. E60, o1147-o1148.],d[Kirsop, P., Storey, J. M. D. & Harrison, W. T. A. (2004d). Acta Cryst. E60, o1636-o1638.]).

[Scheme 1]

There are two independent mol­ecules of (I)[link] (Fig. 1[link]). Both appear to possess their expected geometrical parameters, allowing for the rather low bond precisions obtained in this study. The C1-containing species is unexceptional. With respect to the mean plane of the C1–C6 benzene ring, one of the side-arm terminal Br atoms points `up' [the displacement of Br2 is 1.790 (12) Å] and one points `down' [the displacement of Br3 is −1.792 (12) Å].

The most inter­esting feature of the structure is the whole-mol­ecule disorder displayed by the C11-containing mol­ecule. This arises from inversion symmetry at the point (1, [1\over2], [1\over2]) and symmetry-related locations. The resulting overlapped mol­ecules (Fig. 2[link]) are constrained by symmetry to have equal population parameters of 0.5 for all atoms in the mol­ecule. As with the C1-containing mol­ecule, the two side-arm terminal Br atoms are displaced in opposite senses with respect to the mean plane of the C11–C16 benzene ring [with displacements for Br12 and Br13 of 1.825 (16) and −1.74 (3) Å, respectively]. This situation of one ordered and one disordered mol­ecule results in the atypical situation of Z′ = 1.5 and Z = 6 for a monoclinic system.

As well as van der Waals forces, the crystal packing is influenced by ππ stacking inter­actions involving the C1-containing mol­ecule (Fig. 3[link]) generated by the c-glide symmetry operation. The CgCgi separation [Cg is the centroid of the C1–C6 ring; symmetry code: (i) x, [{3\over 2}]y, [{1\over 2}] + x] is 3.755 (4) Å and the C1–C6/C1i–C6i interplanar separation is 3.411 Å. A PLATON (Spek, 2003[Spek, A. L. (2003). J. Appl. Cryst. 36, 7-13.]) analysis of (I)[link] revealed a slightly short Br1⋯Br11ii contact of 3.595 (2) Å [symmetry code: (ii) 2 − x, 1 − y, 1 − z], some 0.1 Å less than the van der Waals radius sum of 3.70 Å (Spek, 2003[Spek, A. L. (2003). J. Appl. Cryst. 36, 7-13.]). Such Br⋯Br contacts are quite common and their significance – specific attractive forces (Desiraju & Parthasarathy, 1989[Desiraju, G. R. & Parthasarathy, R. (1989). J. Am. Chem. Soc. 111, 8725-8726.]) or packing contacts (Eriksson & Hu, 2001[Eriksson, L. & Hu, J. (2001). Acta Cryst. E57, o930-o932.]) – has been debated.

The packing of (I)[link] is shown in Fig. 4[link], indicating how the ordered and disordered mol­ecules segregate into (010) sheets. Because the C11-containing mol­ecules are almost perpendicular to, and are sandwiched between, the ππ stacks of C1-containing mol­ecules, there can be no ππ forces involving the former mol­ecules [the dihedral angle between the C1–C6 and C11–C16 mean planes is 80.8 (6)°].

Aside from very simple mol­ecules and fragments, whole-mol­ecule disorder (WMD) is not particularly common. A classic example is the 10 π electron mol­ecule azulene, C10H8, containing fused, planar, five- and seven-membered rings. After several conflicting studies it was concluded (Robertson et al., 1962[Robertson, J. M., Shearer, H. M. M., Sim, G. A. & Watson, D. G. (1962). Acta Cryst. 15, 1-8.]) that azulene shows WMD with the 5/7 and 7/5 conformations overlapped at random. More recently, Ichharam & Boeyens (2001[Ichharam, V. & Boeyens, J. C. A. (2001). Cryst. Eng. 4, 171-178.]) observed WMD in 2-(2-thien­yl)-1-(2-pyrazin­yl)ethene and 2-(2-thien­yl)-1-(2-quinoxalin­yl)ethene. In both cases, the disordered components were related by pseudo-twofold axes. Cox & Wardell (2003[Cox, P. J. & Wardell, J. L. (2003). Acta Cryst. C59, o706-o708.]) found WMD in 4,4′-sulfonyl­bis[N-(4-nitro­phenyl­methylene)benzen­amine], with no (pseudo)symmetry relating the two slightly displaced disorder components.

[Figure 1]
Figure 1
A view of (I)[link], showing 50% probability displacement spheres and ellipsoids (H atoms are drawn as spheres of arbitrary radii).
[Figure 2]
Figure 2
A detail of (I)[link], showing the whole-mol­ecule disorder of the C11-containing mol­ecule (50% probability displacement spheres/ellipsoids; all H atoms have been omitted for clarity). Atoms with the suffix A are generated by the symmetry operation (2 − x, 1 − y, 1 − z).
[Figure 3]
Figure 3
A detail of (I)[link], showing the ππ stacking inter­action involving the C1-containing mol­ecule. The mol­ecules containing atoms Br1A and Br1B are generated by the symmetry operations (x, [{3\over 2}]y, [{1\over 2}] + z) and (x, [{3\over 2}]y, z − [{1\over 2}]), respectively.
[Figure 4]
Figure 4
The packing in (I)[link], viewed down [001], with H atoms omitted.

Experimental

2-Bromo-1,3-dimethyl­benzene (5.0 g, 0.027 mol), N-bromosuccin­amide (NBS, 9.6 g, 0.054 mol) and azobisisobutyronitrile (0.88 g, 0.0054 mol) were added to chloro­form (100 ml). The mixture was stirred at reflux under a nitro­gen atmosphere for 12 h. After cooling, the mixture was filtered and the solvent was removed at reduced pressure to give a yellow solid. Thin-layer chromatography (hexane) showed 2-bromo-1,3-bis(bromo­methyl)benzene as a sharp spot at RF = 0.21. The NBS residues were removed by flash column chromatography (20:1 hexane–ethyl acetate) and the solvent was removed. The product was washed with hexane, giving a white solid (4.9 g, 53%). A sample was recrystallized from hot hexane–ethyl acetate (20:1) to give clear needles of (I)[link] [m.p. 371–373 K, literature (Newcombe et al., 1977[Newcombe, M., Moore, S. S. & Cram, D. J. (1977). J. Am. Chem. Soc. 99, 6405-6410.]) 374–376 K]. 1H NMR (CDCl3): δH 4.64 (4H, s, 2 × CH2), 7.28 (1H, t, J = 8.1 Hz, Ar–H), 7.41 (2H, d, J = 8.1 Hz, 2 × Ar–H); 13C NMR (CDCl3): δC 33.8, 126.6, 128.0, 131.3, 138.5.

Crystal data
  • C8H7Br3

  • Mr = 342.87

  • Monoclinic, P 21 /c

  • a = 9.1114 (4) Å

  • b = 22.6016 (10) Å

  • c = 7.5004 (3) Å

  • β = 111.971 (3)°

  • V = 1432.40 (11) Å3

  • Z = 6

  • Dx = 2.385 Mg m−3

  • Mo Kα radiation

  • μ = 12.61 mm−1

  • T = 120 (2) K

  • Blade, colourless

  • 0.60 × 0.10 × 0.01 mm

Data collection
  • Nonius KappaCCD diffractometer

  • ω and φ scans

  • Absorption correction: multi-scan (SORTAV; Blessing, 1995[Blessing, R. H. (1995). Acta Cryst. A51, 33-38.]) Tmin = 0.049, Tmax = 0.940 (expected range = 0.046–0.882)

  • 14563 measured reflections

  • 3266 independent reflections

  • 2406 reflections with I > 2σ(I)

  • Rint = 0.099

  • θmax = 27.6°

Refinement
  • Refinement on F2

  • R[F2 > 2σ(F2)] = 0.084

  • wR(F2) = 0.253

  • S = 1.01

  • 3266 reflections

  • 146 parameters

  • H-atom parameters constrained

  • w = 1/[σ2(Fo2) + (0.1847P)2] where P = (Fo2 + 2Fc2)/3

  • (Δ/σ)max < 0.001

  • Δρmax = 1.89 e Å−3

  • Δρmin = −2.79 e Å−3

The C1-containing mol­ecule was located and refined straightforwardly. The C11-containing mol­ecule evidently showed massive disorder. By careful analysis of difference maps, the disorder could be resolved into two overlapped symmetry-related mol­ecules of (I)[link] (as described in the Comment). The C atoms of the disordered mol­ecule were refined isotropically. All H atoms were placed in calculated positions (C—H = 0.95–0.99 Å) and refined as riding, with Uiso(H) values of 1.2Ueq(C). The largest difference peak is 1.04 Å from atom Br2 and the deepest difference hole is 0.85 Å from the same atom. Attempts to model the crystal in lower-symmetry space groups were not successful.

Data collection: COLLECT (Nonius, 1998[Nonius (1998). COLLECT. Nonius BV, Delft, The Netherlands.]); cell refinement: SCALEPACK (Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press.]); data reduction: DENZO (Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press.]), SCALEPACK and SORTAV (Blessing, 1995[Blessing, R. H. (1995). Acta Cryst. A51, 33-38.]); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.]); molecular graphics: ORTEP-3 (Farrugia, 1997[Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.]); software used to prepare material for publication: SHELXL97.

Supporting information


Comment top

The title compound, (I), prepared earlier by Newcombe et al. (1977), arose during our ongoing studies to determine the philicity of aryl radicals by competetive cyclization reactions (Kirsop et al., 2004a,b,c,d).

There are two independent molecules of (I) (Fig. 1). Both appear to possess their expected geometrical parameters, allowing for the rather low bond precisions obtained in this study. The C1-containing species is unexceptional. With respect to the mean plane of the C1–C6 benzene ring, one of the side-arm terminal Br atoms points `up' [the displacement of Br2 = 1.790 (12) Å] and one points `down' [the displacement of Br3 = −1.792 (12) Å].

The most interesting feature of the structure is the whole-molecule disorder displayed by the C11-containing molecule. This arises from inversion symmetry at the point (1, 1/2, 1/2) and symmetry-related locations. The resulting overlapped molecules (Fig. 2) are constrained by symmetry to have equal population parameters of 0.5 for all atoms in the molecule. As with the C1-containing molecule, the two side-arm terminal Br atoms are displaced in opposite senses with respect to the mean plane of the C11–C16 benzene ring [with displacements for Br12 and Br13 of 1.825 (16) and −1.74 (3) Å, respectively]. This situation of one ordered and one disordered molecule results in the atypical situation of Z' = 1.5 and Z = 6 for a monoclinic system.

As well as van der Waals forces, the crystal packing is influenced by ππ stacking interactions involving the C1-containing molecule (Fig. 3) generated by the c-glide symmetry operation. The Cg···Cgi [Cg is the centroid of the C1–C6 ring; symmetry code: (i) x, 3/2 − y, 1/2 + x] separation is 3.755 (4) Å and the C1–C6/C1i–C6i inter-planar speration is 3.411 Å. A PLATON (Spek, 2003) analysis of (I) revealed a slightly short Br1···Br11ii contact of 3.595 (2) Å [symmetry code: (ii) 2 − x, 1 − y, 1 − x], some 0.1 Å less than the Br···Br van der Waals radius sum of 3.70 Å (Spek, 2003). Such Br···Br contacts are quite common and their significance – specific attractive forces (Desiraju & Parthasarathy, 1989) or packing contacts (Eriksson & Hu, 2001) – has been debated.

The packing of (I) is shown in Fig. 4, indicating how the ordered and disordered molecules segregate into (010) sheets. Because the C11-containing molecules are almost perpendicular to, and are sandwiched between, the ππ stacks of C1-containing molecules there can be no ππ forces involving the former molecules [the dihedral angle between the C1–C6 and C11–C16 mean planes is 80.8 (6)°].

Aside from very simple molecules and fragments, whole-molecule disorder (WMD) is not particularly common. A classic example is the 10-π electron molecule azulene, C10H8, containing fused, planar, five- and seven-membered rings. After several conflicting studies it was concluded (Robertson et al., 1962) that azulene shows WMD with the 5/7 and 7/5 conformations overlapped at random. More recently, Ichharam & Boeyens (2001) observed WMD in 2–2(thienyl)-1-(2-pyrazinyl)ethane, C10H8N2S, and 2–2(thienyl)-1-(2-quinoxalinyl)ethane, C14H10N2S. In both cases, the disordered components were related by pseudo-twofold axes. Cox & Wardell (2003) found WMD in 4,4'-sulfonylbis[N-(4-nitrophenylmethylene)benzenamine], C26H18N4O6S, with no (pseudo)symmetry relating the two slightly displaced disorder components.

Experimental top

2-Bromo-1,3-dimethylbenzene (5.0 g, 0.027 mol), N-bromosuccinamide (NBS, 9.6 g, 0.054 mol) and azobisisobutyronitrile (AIBN, 0.88 g, 0.0054 mol) were added to chloroform (100 ml). The mixture was stirred at reflux under a nitrogen atmosphere for 12 h. After cooling, the mixture was filtered and the solvent was removed at reduced pressure to give a yellow solid. Thin layer chromatography (hexane) showed 2-bromo-1,3-bis-bromomethyl-benzene as a sharp spot at Rf = 0.21. The NBS residues were removed by flash column chromatography (20:1 hexane–ethyl acetate) and the solvent was removed. The product was washed in hexane giving a white solid (4.9 g, 53%). A sample was recrystallized from hot hexane–ethyl acetate (20:1) to give clear needles of (I) [m.p. 371–373 K, literature (Newcombe et al., 1977) 374–376 K]. 1H NMR (CDCl3): δH 4.64 (4H, s, 2 × CH2), 7.28 (1H, t, J = 8.1 Hz, Ar—H), 7.41 (2H, d, J = 8.1 Hz, 2 × Ar—H); 13C NMR (CDCl3): δC 33.8, 126.6, 128.0, 131.3, 138.5.

Refinement top

The C1-containing molecule was located and refined straightforwardly. The C11-containing molecule evidently showed massive disorder. By careful analysis of difference maps, the disorder could be resolved into two overlapped symmetry-related molecules of (I) as described above. The C atoms of the disordered molecule were refined isotropically. All H atoms were placed in calculated positions (C—H = 0.95–0.99 Å) and refined as riding with Uiso(H) = 1.2Ueq(carrier atom). The largest difference peak is 1.04 Å from Br2 and the deepest difference hole is 0.85 Å from Br2. Attempts to model the crystal in lower-symmetry space groups were not successful.

Computing details top

Data collection: Collect (Nonius, 1998); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997); data reduction: HKL DENZO (Otwinowski & Minor, 1997) and SCALEPACK, and SORTAV (Blessing, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. A view of (I), showing 50% probability displacement spheres and ellipsoids (H atoms are drawn as spheres of arbitrary radii).
[Figure 2] Fig. 2. A detail of (I), showing the whole-molecule disorder of the C11-containing molecule (50% displacement spheres/ellipsoids; all H atoms have been omitted for clarity). Atoms with the suffix a are generated by the symmetry operation (2 − x, 1 − y, 1 − z).
[Figure 3] Fig. 3. A detail of (I), showing the ππ stacking interaction involving the C1-containing molecule. The molecules containing Br1a and Btr1b are generated by the symmetry operations (x, 3/2 − y, 1/2 + z) and (x, 3/2 − y, z − 1/2), respectively.
[Figure 4] Fig. 4. The packing in (I), viewed down [001], with H atoms omitted.
2-Bromo-1,3-bis(bromomethyl)benzene top
Crystal data top
C8H7Br3F(000) = 960
Mr = 342.87Dx = 2.385 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 3208 reflections
a = 9.1114 (4) Åθ = 2.9–27.5°
b = 22.6016 (10) ŵ = 12.61 mm1
c = 7.5004 (3) ÅT = 120 K
β = 111.971 (3)°Blade, colourless
V = 1432.40 (11) Å30.60 × 0.10 × 0.01 mm
Z = 6
Data collection top
Nonius KappaCCD
diffractometer
3266 independent reflections
Radiation source: fine-focus sealed tube2406 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.099
ω and ϕ scansθmax = 27.6°, θmin = 3.0°
Absorption correction: multi-scan
(SORTAV; Blessing, 1995)
h = 1111
Tmin = 0.049, Tmax = 0.940k = 2829
14563 measured reflectionsl = 99
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.084Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.253H-atom parameters constrained
S = 1.02 w = 1/[σ2(Fo2) + (0.1847P)2]
where P = (Fo2 + 2Fc2)/3
3266 reflections(Δ/σ)max < 0.001
146 parametersΔρmax = 1.89 e Å3
18 restraintsΔρmin = 2.79 e Å3
Crystal data top
C8H7Br3V = 1432.40 (11) Å3
Mr = 342.87Z = 6
Monoclinic, P21/cMo Kα radiation
a = 9.1114 (4) ŵ = 12.61 mm1
b = 22.6016 (10) ÅT = 120 K
c = 7.5004 (3) Å0.60 × 0.10 × 0.01 mm
β = 111.971 (3)°
Data collection top
Nonius KappaCCD
diffractometer
3266 independent reflections
Absorption correction: multi-scan
(SORTAV; Blessing, 1995)
2406 reflections with I > 2σ(I)
Tmin = 0.049, Tmax = 0.940Rint = 0.099
14563 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.08418 restraints
wR(F2) = 0.253H-atom parameters constrained
S = 1.02Δρmax = 1.89 e Å3
3266 reflectionsΔρmin = 2.79 e Å3
146 parameters
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*/UeqOcc. (<1)
C10.8454 (10)0.6929 (4)0.7788 (10)0.0206 (17)
C20.7173 (10)0.7232 (4)0.7914 (10)0.0178 (15)
C30.7214 (11)0.7863 (4)0.7936 (11)0.0195 (17)
H30.63390.80810.79860.023*
C40.8526 (11)0.8155 (4)0.7887 (11)0.0236 (19)
H40.85530.85750.79230.028*
C50.9812 (11)0.7846 (4)0.7786 (11)0.0215 (18)
H51.06930.80580.77280.026*
C60.9828 (10)0.7233 (4)0.7768 (10)0.0198 (17)
C70.5713 (11)0.6931 (4)0.7972 (11)0.0237 (18)
H7A0.51700.72010.85660.028*
H7B0.60310.65730.87860.028*
C81.1180 (12)0.6912 (4)0.7647 (12)0.029 (2)
H8A1.17790.71780.71180.034*
H8B1.07900.65750.67480.034*
Br10.83970 (12)0.60963 (4)0.76676 (13)0.0314 (3)
Br20.42421 (11)0.67059 (4)0.54093 (12)0.0251 (3)
Br31.26224 (12)0.66087 (4)1.01763 (12)0.0271 (3)
C111.0313 (14)0.5093 (6)0.4755 (12)0.027 (4)*0.50
C121.1455 (11)0.5068 (5)0.6607 (14)0.018 (3)*0.50
C131.1082 (14)0.4830 (6)0.8093 (11)0.028 (3)*0.50
H131.18620.48130.93580.034*0.50
C140.9567 (17)0.4616 (6)0.7728 (16)0.028 (3)*0.50
H140.93120.44530.87440.034*0.50
C150.8425 (12)0.4640 (6)0.5877 (19)0.038 (5)*0.50
H150.73900.44930.56270.045*0.50
C160.8798 (12)0.4878 (6)0.4391 (13)0.029 (4)*0.50
C171.314 (2)0.5274 (7)0.719 (2)0.021 (3)*0.50
H17A1.35140.54340.85140.026*0.50
H17B1.31980.55960.63220.026*0.50
C180.756 (3)0.4905 (10)0.240 (3)0.042 (5)*0.50
H18A0.69960.45220.21010.051*0.50
H18B0.80910.49620.14730.051*0.50
Br111.0902 (3)0.54495 (9)0.2818 (3)0.0364 (6)0.50
Br121.4532 (3)0.46312 (11)0.7090 (4)0.0479 (6)0.50
Br130.6022 (3)0.55394 (10)0.2047 (4)0.0465 (6)0.50
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.025 (5)0.026 (4)0.007 (3)0.004 (3)0.001 (3)0.002 (3)
C20.017 (4)0.026 (3)0.005 (3)0.002 (3)0.002 (3)0.001 (3)
C30.023 (4)0.023 (4)0.010 (3)0.002 (3)0.004 (3)0.002 (3)
C40.032 (6)0.026 (4)0.014 (4)0.003 (4)0.009 (4)0.000 (3)
C50.021 (5)0.027 (4)0.012 (3)0.008 (3)0.001 (3)0.002 (3)
C60.015 (4)0.034 (4)0.009 (3)0.000 (3)0.002 (3)0.005 (3)
C70.030 (5)0.027 (4)0.015 (3)0.001 (4)0.009 (3)0.000 (3)
C80.028 (5)0.037 (5)0.017 (4)0.007 (4)0.004 (4)0.003 (4)
Br10.0344 (7)0.0214 (5)0.0355 (6)0.0023 (4)0.0097 (5)0.0019 (3)
Br20.0234 (6)0.0272 (5)0.0221 (5)0.0053 (3)0.0056 (4)0.0053 (3)
Br30.0250 (6)0.0346 (5)0.0196 (5)0.0053 (4)0.0057 (4)0.0031 (3)
Br110.0602 (17)0.0251 (10)0.0256 (10)0.0130 (9)0.0181 (11)0.0065 (8)
Br120.0373 (14)0.0436 (13)0.0576 (15)0.0085 (11)0.0116 (12)0.0166 (12)
Br130.0413 (15)0.0288 (11)0.0500 (14)0.0072 (10)0.0052 (12)0.0114 (10)
Geometric parameters (Å, º) top
C1—C21.387 (12)C11—C121.3900
C1—C61.432 (12)C11—C161.3900
C1—Br11.884 (9)C11—Br111.907 (8)
C2—C31.426 (12)C12—C131.3900
C2—C71.510 (13)C12—C171.51 (2)
C3—C41.379 (12)C13—C141.3900
C3—H30.9500C13—H130.9500
C4—C51.390 (13)C14—C151.3900
C4—H40.9500C14—H140.9500
C5—C61.386 (12)C15—C161.3900
C5—H50.9500C15—H150.9500
C6—C81.462 (13)C16—C181.50 (2)
C7—Br21.955 (9)C17—Br121.945 (17)
C7—H7A0.9900C17—H17A0.9900
C7—H7B0.9900C17—H17B0.9900
C8—Br31.982 (9)C18—Br131.95 (2)
C8—H8A0.9900C18—H18A0.9900
C8—H8B0.9900C18—H18B0.9900
C2—C1—C6121.6 (8)C12—C11—C16120.0
C2—C1—Br1119.2 (6)C12—C11—Br11117.3 (6)
C6—C1—Br1119.1 (7)C16—C11—Br11122.7 (6)
C1—C2—C3118.4 (8)C13—C12—C11120.0
C1—C2—C7123.5 (8)C13—C12—C17114.6 (10)
C3—C2—C7118.0 (8)C11—C12—C17125.4 (10)
C4—C3—C2119.8 (8)C12—C13—C14120.0
C4—C3—H3120.1C12—C13—H13120.0
C2—C3—H3120.1C14—C13—H13120.0
C3—C4—C5121.1 (9)C13—C14—C15120.0
C3—C4—H4119.4C13—C14—H14120.0
C5—C4—H4119.4C15—C14—H14120.0
C6—C5—C4121.1 (8)C16—C15—C14120.0
C6—C5—H5119.5C16—C15—H15120.0
C4—C5—H5119.5C14—C15—H15120.0
C5—C6—C1117.8 (8)C15—C16—C11120.0
C5—C6—C8120.6 (8)C15—C16—C18119.8 (13)
C1—C6—C8121.5 (8)C11—C16—C18120.2 (13)
C2—C7—Br2112.1 (5)C12—C17—Br12111.5 (11)
C2—C7—H7A109.2C12—C17—H17A109.3
Br2—C7—H7A109.2Br12—C17—H17A109.3
C2—C7—H7B109.2C12—C17—H17B109.3
Br2—C7—H7B109.2Br12—C17—H17B109.3
H7A—C7—H7B107.9H17A—C17—H17B108.0
C6—C8—Br3112.6 (6)C16—C18—Br13113.5 (14)
C6—C8—H8A109.1C16—C18—H18A108.9
Br3—C8—H8A109.1Br13—C18—H18A108.9
C6—C8—H8B109.1C16—C18—H18B108.9
Br3—C8—H8B109.1Br13—C18—H18B108.9
H8A—C8—H8B107.8H18A—C18—H18B107.7
C6—C1—C2—C32.8 (11)C16—C11—C12—C130.0
Br1—C1—C2—C3177.9 (5)Br11—C11—C12—C13178.0 (10)
C6—C1—C2—C7179.0 (7)C16—C11—C12—C17178.7 (13)
Br1—C1—C2—C70.4 (10)Br11—C11—C12—C173.2 (13)
C1—C2—C3—C41.7 (11)C11—C12—C13—C140.0
C7—C2—C3—C4179.9 (7)C17—C12—C13—C14178.9 (12)
C2—C3—C4—C51.0 (11)C12—C13—C14—C150.0
C3—C4—C5—C61.2 (11)C13—C14—C15—C160.0
C4—C5—C6—C12.2 (11)C14—C15—C16—C110.0
C4—C5—C6—C8179.5 (7)C14—C15—C16—C18179.8 (15)
C2—C1—C6—C53.0 (11)C12—C11—C16—C150.0
Br1—C1—C6—C5177.6 (5)Br11—C11—C16—C15177.9 (11)
C2—C1—C6—C8179.6 (7)C12—C11—C16—C18179.8 (15)
Br1—C1—C6—C80.3 (10)Br11—C11—C16—C181.9 (14)
C1—C2—C7—Br281.2 (9)C13—C12—C17—Br1286.4 (11)
C3—C2—C7—Br297.0 (7)C11—C12—C17—Br1292.4 (12)
C5—C6—C8—Br3100.6 (8)C15—C16—C18—Br1376.6 (16)
C1—C6—C8—Br382.1 (9)C11—C16—C18—Br13103.2 (14)

Experimental details

Crystal data
Chemical formulaC8H7Br3
Mr342.87
Crystal system, space groupMonoclinic, P21/c
Temperature (K)120
a, b, c (Å)9.1114 (4), 22.6016 (10), 7.5004 (3)
β (°) 111.971 (3)
V3)1432.40 (11)
Z6
Radiation typeMo Kα
µ (mm1)12.61
Crystal size (mm)0.60 × 0.10 × 0.01
Data collection
DiffractometerNonius KappaCCD
diffractometer
Absorption correctionMulti-scan
(SORTAV; Blessing, 1995)
Tmin, Tmax0.049, 0.940
No. of measured, independent and
observed [I > 2σ(I)] reflections
14563, 3266, 2406
Rint0.099
(sin θ/λ)max1)0.651
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.084, 0.253, 1.02
No. of reflections3266
No. of parameters146
No. of restraints18
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)1.89, 2.79

Computer programs: Collect (Nonius, 1998), HKL SCALEPACK (Otwinowski & Minor, 1997), HKL DENZO (Otwinowski & Minor, 1997) and SCALEPACK, and SORTAV (Blessing, 1995), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 (Farrugia, 1997), SHELXL97.

 

Acknowledgements

The authors thank the EPSRC UK National Crystallography Service for the data collection.

References

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