organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2056-9890

(5Z,7Z,9Z)-5,10-Di­bromo­benzo[8]annulene

aDepartment of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, AB, T1K3M4, Canada
*Correspondence e-mail: boere@uleth.ca

(Received 10 September 2013; accepted 10 October 2013; online 16 October 2013)

In the structure of the title compound, C12H8Br2, the two bromine substituents are oriented exo to the boat-shaped cyclo­octa­tetra­ene at the two ring sites that are β to the ring fusion positions. The average Br—C bond distance is 1.919 (2) Å, the average distance for C=C double bonds that are Br substituted is 1.328 (2) Å, while the other two double-bond distances are 1.327 (2) and 1.398 (2) Å for the non-fused and fused bonds, respectively. Each type of ring inter­atomic distance is within s.u. of the average values for the four known structures, including the title compound, of benzo-fused cyclo­ocata­tetra­enes that are not coordinated to a metal atom. The crystal structure features short Br⋯Br [3.6620 (3) Å] and C⋯H [2.834 (2) and 2.841 (2) Å] contacts.

Related literature

For general background to photochemical conversions of benzo­cyclo­octa­tetra­enes, see: Bender et al. (1982[Bender, C. O., Bengtson, D. L., Dolman, D., Herle, C. E. L. & O'Shea, S. F. (1982). Can. J. Chem. 60, 1942-1952.], 1986[Bender, C. O., Bengtson, D. L., Dolman, D. & O'Shea, S. F. (1986). Can. J. Chem. 64, 237-245.], 1988[Bender, C. O., Dolman, D. & Murthy, G. K. (1988). Can. J. Chem. 66, 1656-1662.], 1991[Bender, C. O., Clyne, D. S. & Dolman, D. (1991). Can. J. Chem. 69, 70-76.]). For details of the synthesis, see: Barton et al. (1964[Barton, J. W., Henn, D. E., McLaughlan, K. A. & McOmie, J. F. W. (1964). J. Chem. Soc. pp. 1622-1625.]). For related structures, see: Bohshar et al. (1984[Bohshar, M., Maas, G., Heydt, H. & Regitz, M. (1984). Tetrahedron, 40, 5171-5176.]); Çelik et al. (2002[Çelik, I., Tutar, A., Akkurt, M., Özcan, Y. & Çakmak, O. (2002). Acta Cryst. E58, o314-o316.]); Jones et al. (1994[Jones, R., Scheffer, J. R., Trotter, J. & Yap, M. (1994). Acta Cryst. B50, 597-600.]), Kidokoro et al. (1983[Kidokoro, H., Saito, Y., Sato, M., Ebine, S., Sato, S., Hata, T. & Tamura, C. (1983). Bull. Chem. Soc. Jpn, 56, 1192-1195.]); Li et al. (1983[Li, W.-K., Chiu, S.-W., Mak, T. C. W. & Huang, N. Z. (1983). J. Mol. Struct. (THEOCHEM), 94, 285-291.]). For a description of the Cambridge Structural Database, see: Allen (2002[Allen, F. H. (2002). Acta Cryst. B58, 380-388.]). For the PLATON suite of crystallographic software, see: Spek (2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]).

[Scheme 1]

Experimental

Crystal data
  • C12H8Br2

  • Mr = 312.00

  • Monoclinic, P 21 /c

  • a = 8.5289 (5) Å

  • b = 8.3630 (5) Å

  • c = 15.5645 (9) Å

  • β = 105.2980 (6)°

  • V = 1070.83 (11) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 7.52 mm−1

  • T = 173 K

  • 0.16 × 0.09 × 0.08 mm

Data collection
  • Bruker APEXII CCD area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 2008[Bruker (2008). APEX2, SAINT-Plus and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.510, Tmax = 0.746

  • 15053 measured reflections

  • 2426 independent reflections

  • 2217 reflections with I > 2σ(I)

  • Rint = 0.023

Refinement
  • R[F2 > 2σ(F2)] = 0.017

  • wR(F2) = 0.039

  • S = 1.04

  • 2426 reflections

  • 127 parameters

  • H-atom parameters constrained

  • Δρmax = 0.49 e Å−3

  • Δρmin = −0.46 e Å−3

Data collection: APEX2 (Bruker, 2008[Bruker (2008). APEX2, SAINT-Plus and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT-Plus (Bruker, 2008[Bruker (2008). APEX2, SAINT-Plus and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXD (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: Mercury (Macrae et al., 2006[Macrae, C. F., Edgington, P. R., McCabe, P., Pidcock, E., Shields, G. P., Taylor, R., Towler, M. & van de Streek, J. (2006). J. Appl. Cryst. 39, 453-457.]); software used to prepare material for publication: publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).

Supporting information


Comment top

The title compound was prepared as a starting material for synthesis of the corresponding dinitrile derivative, which was of interest in connection with studies of the photochemical conversions of benzocyclooctatetraenes (Bender et al., 1982; 1986; 1988; 1991). In view of the paucity of structures that are crystallographically established for mono-benzofused cyclo-octatetraenes, we decided to undertake a crystallographic study of (I).

Only three prior structures have been reported which contain one benzo-fused cyclooctatetraene ring according to the Cambridge Structural Database (Allen, 2002; WebCSD, August 2013), excluding those with rings coordinated to metals. The parent hydrocarbon, (5Z,7Z,9Z)-benzo[8]annulene (refcode BUYYUP), has been structurally characterized by X-ray crystallography and investigated by semi-empirical quantum mechanical methods (Li et al., 1983). The only halogen-substituted example is (8-chlorobenzocyclooctatetraen-6-yl)-diphenylphosphine-oxide (refcode: CUDYUV) but this ring bears a large Ph2P=O substituent; this structure contains two independent molecules in the asymetric unit (Bohshar et al., 1984). In dimethyl 1,4,6,9-tetramethylbenzocyclooctatetraene-5,10-dicarboxylate (refcode: LEZMAE) the two methyl ester substituents are located where the Br atoms are in (I) but this molecule also has four methyl substituents, two attached to the other ends of the same double bonds that the esters are attached to, and two in the 1 and 4 positions of the benzene rings (Jones et al., 1994). Gratifyingly, all the 1,2 interatomic distances in (I) are found to lie within s.u. of the average values from these three comparison structures and (I).

Related benzo-fused cyclooctatrienes which have the same 5,8-dibromo substitution as found in (I) have been structurally characterized. In 5,8,10-tribromo-(8H)-benzocycloocten-7-one (refcode: BOGWAV) the cyclooctatriene ring is distorted by saturation at C8 and a ketone group at C7 (Kidokoro et al., 1983), whilst 5,7,7,8,10-pentabromo-7,8-dihydrobenzocyclooctene (refcode: FABDOC) has C7 with two Br and C8 with H and Br substituents (Çelik et al., 2002). The C5-Br1 and C10-Br2 distances in BOGWAV are 1.8822 (3) and 1.9309 (3) Å and in FABDOC 1.912 (7) and 1.896 (9). Thus the average C-Br bond distance in this set of three related structures is 1.910 (16) Å, with the distances in (I) found within s.u. of this value.

In the crystal structure of (I) molecules are tightly packed. There are three unique short intermolecular contacts (Figure 2), namely C2···H7i = H7···C2ii = 2.834 (2) Å, Br1···Br2iii = 3.6620 (3) Å and C9···H1iv = 2.841 (2) Å (symcodes employed: i, 1-x,-1/2+y,1/2-z; ii, 1-x,1/2+y,1/2-z; iii, -x,1-y,-z; iv, 1-x,-y,-z).

Related literature top

For general background to photochemical conversions of benzocyclooctatetraenes, see: Bender et al. (1982, 1986, 1988, 1991). For details of the synthesis, see: Barton et al. (1964). For related structures, see: Bohshar et al. (1984); Çelik et al. (2002); Jones et al. (1994), Kidokoro et al. (1983); Li et al. (1983). For a description of the Cambridge Structural Database, see: Allen (2002). For the PLATON suite of crystallographic software, see: Spek (2009).

Experimental top

Samples of (I) were prepared from biphenylene via the method of Barton et al. (1964). Crystals were obtained from aqueous methanol (m.p. 366–368 K).

Refinement top

All the hydrogen atoms were located on a difference map, but for purposes of refinement are treated as riding on their attached aromatic carbon atoms with C—H = 0.95 Å and Uiso(H) = 1.2Ueq(C).

Computing details top

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT-Plus (Bruker, 2008); data reduction: SAINT-Plus (Bruker, 2008); program(s) used to solve structure: SHELXD (Sheldrick, 2008); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top
[Figure 1] Fig. 1. Molecular structure of (I) drawn with displacement elipsoids at the 40% probability level, and also showing the atom numbering scheme.
[Figure 2] Fig. 2. View along the a axis (with b horizontal and c vertical) showing the three unique intermolecular contacts (as dashed-line tubes) that are less than the sums of the v.d. Waals' radii of the interacting atoms. (Symcodes: i, 1-x,-1/2+y,1/2-z; ii, 1-x,1/2+y,1/2-z; iii, -x,1-y,-z; iv, 1-x,-y,-z.)
(5Z,7Z,9Z)-5,10-Dibromobenzo[8]annulene top
Crystal data top
C12H8Br2Dx = 1.935 Mg m3
Mr = 312.00Melting point: 366 K
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
a = 8.5289 (5) ÅCell parameters from 9956 reflections
b = 8.3630 (5) Åθ = 2.5–29.0°
c = 15.5645 (9) ŵ = 7.52 mm1
β = 105.2980 (6)°T = 173 K
V = 1070.83 (11) Å3Block, colourless
Z = 40.16 × 0.09 × 0.08 mm
F(000) = 600
Data collection top
Bruker APEXII CCD area-detector
diffractometer
2426 independent reflections
Radiation source: fine-focus sealed tube, Bruker D82217 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.023
Detector resolution: 66.06 pixels mm-1θmax = 27.4°, θmin = 2.5°
ϕ and ω scansh = 1111
Absorption correction: multi-scan
(SADABS; Bruker, 2008)
k = 1010
Tmin = 0.510, Tmax = 0.746l = 2020
15053 measured reflections
Refinement top
Refinement on F2Primary atom site location: dual
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.017Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.039H-atom parameters constrained
S = 1.04 w = 1/[σ2(Fo2) + (0.0171P)2 + 0.5892P]
where P = (Fo2 + 2Fc2)/3
2426 reflections(Δ/σ)max = 0.001
127 parametersΔρmax = 0.49 e Å3
0 restraintsΔρmin = 0.46 e Å3
Crystal data top
C12H8Br2V = 1070.83 (11) Å3
Mr = 312.00Z = 4
Monoclinic, P21/cMo Kα radiation
a = 8.5289 (5) ŵ = 7.52 mm1
b = 8.3630 (5) ÅT = 173 K
c = 15.5645 (9) Å0.16 × 0.09 × 0.08 mm
β = 105.2980 (6)°
Data collection top
Bruker APEXII CCD area-detector
diffractometer
2426 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2008)
2217 reflections with I > 2σ(I)
Tmin = 0.510, Tmax = 0.746Rint = 0.023
15053 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0170 restraints
wR(F2) = 0.039H-atom parameters constrained
S = 1.04Δρmax = 0.49 e Å3
2426 reflectionsΔρmin = 0.46 e Å3
127 parameters
Special details top

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. Structure first solved in P21; used the PLATON "Addsym" tool to find the true space group and refinement continued in P21/c (Spek, 2009).

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Br10.00196 (2)0.47441 (2)0.12658 (2)0.02901 (6)
Br20.33582 (2)0.24542 (2)0.10638 (2)0.02977 (6)
C10.2640 (2)0.0177 (2)0.03420 (12)0.0251 (4)
H10.31690.05720.00810.030*
C20.1703 (2)0.1200 (2)0.06965 (13)0.0289 (4)
H20.15980.22910.05220.035*
C30.0918 (2)0.0629 (2)0.13055 (12)0.0287 (4)
H30.02850.13320.15570.034*
C40.1056 (2)0.0963 (2)0.15478 (11)0.0240 (4)
H40.04960.13510.19580.029*
C4A0.20053 (19)0.2013 (2)0.11986 (10)0.0187 (3)
C50.2100 (2)0.3709 (2)0.14745 (11)0.0210 (3)
C60.3398 (2)0.4538 (2)0.19030 (12)0.0264 (4)
H60.32350.56150.20540.032*
C70.5062 (2)0.3917 (2)0.21606 (12)0.0282 (4)
H70.56150.39440.27760.034*
C80.5866 (2)0.3322 (2)0.16108 (12)0.0270 (4)
H80.69350.29380.18670.032*
C90.5240 (2)0.3205 (2)0.06401 (12)0.0239 (4)
H90.58510.37140.02890.029*
C100.3892 (2)0.2449 (2)0.02106 (11)0.0206 (3)
C10A0.28235 (19)0.1430 (2)0.05945 (11)0.0187 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Br10.02787 (10)0.02768 (10)0.03510 (11)0.00464 (7)0.01468 (8)0.00192 (8)
Br20.02890 (10)0.04284 (12)0.01930 (9)0.00265 (8)0.00940 (7)0.00122 (7)
C10.0269 (9)0.0217 (9)0.0237 (9)0.0048 (7)0.0016 (7)0.0011 (7)
C20.0294 (9)0.0177 (9)0.0326 (10)0.0018 (7)0.0041 (8)0.0015 (8)
C30.0240 (9)0.0264 (10)0.0308 (10)0.0070 (7)0.0016 (7)0.0094 (8)
C40.0202 (8)0.0286 (9)0.0229 (8)0.0020 (7)0.0052 (7)0.0032 (7)
C4A0.0173 (7)0.0198 (8)0.0170 (8)0.0005 (6)0.0012 (6)0.0014 (6)
C50.0233 (8)0.0227 (9)0.0193 (8)0.0011 (7)0.0098 (6)0.0007 (7)
C60.0338 (10)0.0236 (9)0.0233 (9)0.0048 (8)0.0101 (7)0.0057 (7)
C70.0277 (9)0.0325 (10)0.0214 (9)0.0114 (8)0.0015 (7)0.0010 (8)
C80.0200 (8)0.0298 (10)0.0287 (9)0.0054 (7)0.0019 (7)0.0055 (8)
C90.0223 (8)0.0252 (9)0.0269 (9)0.0008 (7)0.0111 (7)0.0039 (7)
C100.0227 (8)0.0228 (9)0.0178 (8)0.0063 (7)0.0081 (6)0.0011 (6)
C10A0.0171 (7)0.0192 (8)0.0174 (8)0.0009 (6)0.0006 (6)0.0019 (6)
Geometric parameters (Å, º) top
Br1—C51.9234 (17)C4A—C51.478 (2)
Br2—C101.9145 (17)C5—C61.327 (2)
C1—C21.382 (3)C6—C71.465 (3)
C1—C10A1.397 (2)C6—H60.9500
C1—H10.9500C7—C81.326 (3)
C2—C31.381 (3)C7—H70.9500
C2—H20.9500C8—C91.467 (3)
C3—C41.380 (3)C8—H80.9500
C3—H30.9500C9—C101.327 (2)
C4—C4A1.398 (2)C9—H90.9500
C4—H40.9500C10—C10A1.484 (2)
C4A—C10A1.398 (2)
C2—C1—C10A121.12 (17)C5—C6—C7124.91 (17)
C2—C1—H1119.4C5—C6—H6117.5
C10A—C1—H1119.4C7—C6—H6117.5
C3—C2—C1119.75 (17)C8—C7—C6125.79 (16)
C3—C2—H2120.1C8—C7—H7117.1
C1—C2—H2120.1C6—C7—H7117.1
C4—C3—C2119.95 (17)C7—C8—C9125.45 (17)
C4—C3—H3120.0C7—C8—H8117.3
C2—C3—H3120.0C9—C8—H8117.3
C3—C4—C4A121.04 (17)C10—C9—C8125.57 (16)
C3—C4—H4119.5C10—C9—H9117.2
C4A—C4—H4119.5C8—C9—H9117.2
C10A—C4A—C4119.05 (16)C9—C10—C10A127.81 (16)
C10A—C4A—C5122.07 (15)C9—C10—Br2117.29 (13)
C4—C4A—C5118.88 (15)C10A—C10—Br2114.52 (12)
C6—C5—C4A128.45 (16)C1—C10A—C4A119.06 (16)
C6—C5—Br1117.39 (13)C1—C10A—C10118.30 (15)
C4A—C5—Br1113.91 (12)C4A—C10A—C10122.64 (15)
C10A—C1—C2—C30.6 (3)C7—C8—C9—C1057.1 (3)
C1—C2—C3—C40.9 (3)C8—C9—C10—C10A6.8 (3)
C2—C3—C4—C4A1.2 (3)C8—C9—C10—Br2179.26 (14)
C3—C4—C4A—C10A0.0 (2)C2—C1—C10A—C4A1.7 (2)
C3—C4—C4A—C5179.50 (16)C2—C1—C10A—C10177.97 (15)
C10A—C4A—C5—C662.3 (2)C4—C4A—C10A—C11.4 (2)
C4—C4A—C5—C6118.2 (2)C5—C4A—C10A—C1178.05 (15)
C10A—C4A—C5—Br1123.72 (14)C4—C4A—C10A—C10178.29 (15)
C4—C4A—C5—Br155.72 (18)C5—C4A—C10A—C102.3 (2)
C4A—C5—C6—C72.9 (3)C9—C10—C10A—C1118.0 (2)
Br1—C5—C6—C7176.62 (14)Br2—C10—C10A—C154.57 (18)
C5—C6—C7—C858.2 (3)C9—C10—C10A—C4A61.7 (2)
C6—C7—C8—C91.3 (3)Br2—C10—C10A—C4A125.75 (14)

Experimental details

Crystal data
Chemical formulaC12H8Br2
Mr312.00
Crystal system, space groupMonoclinic, P21/c
Temperature (K)173
a, b, c (Å)8.5289 (5), 8.3630 (5), 15.5645 (9)
β (°) 105.2980 (6)
V3)1070.83 (11)
Z4
Radiation typeMo Kα
µ (mm1)7.52
Crystal size (mm)0.16 × 0.09 × 0.08
Data collection
DiffractometerBruker APEXII CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2008)
Tmin, Tmax0.510, 0.746
No. of measured, independent and
observed [I > 2σ(I)] reflections
15053, 2426, 2217
Rint0.023
(sin θ/λ)max1)0.647
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.017, 0.039, 1.04
No. of reflections2426
No. of parameters127
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.49, 0.46

Computer programs: APEX2 (Bruker, 2008), SAINT-Plus (Bruker, 2008), SHELXD (Sheldrick, 2008), SHELXL2013 (Sheldrick, 2008), Mercury (Macrae et al., 2006), publCIF (Westrip, 2010).

 

Acknowledgements

This research was supported by the Natural Sciences and Engineering Research Council of Canada. The diffractometer at the University of Lethbridge X-ray Diffraction Facility was purchased with the help of NSERC and the University.

References

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First citationLi, W.-K., Chiu, S.-W., Mak, T. C. W. & Huang, N. Z. (1983). J. Mol. Struct. (THEOCHEM), 94, 285–291.  CrossRef
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First citationWestrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.  Web of Science CrossRef CAS IUCr Journals

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