exo-10,11-Dibromo­tricyclo­[6.3.1.02,7]dodeca-2,4,6,9-tetra­ene

Johnson, K.R.D.; Bender, C.O.; Boeré, R.T.

doi:10.1107/S1600536811041730

organic compounds

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Volume 67| Part 11| November 2011| Page o2975

doi:10.1107/S1600536811041730

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exo-10,11-Dibromotricyclo[6.3.1.0^2,7]dodeca-2,4,6,9-tetraene

Kevin R. D. Johnson,^a Christopher O. Bender ^a and René T. Boeré ^a ^*

^aDepartment of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, AB, Canada T1K 3M4
^*Correspondence e-mail: boere@uleth.ca

(Received 27 September 2011; accepted 10 October 2011; online 22 October 2011)

The title compound, C₁₂H₁₀Br₂, is a bridged ring system based on a homobenzonorbornadiene framework. The exo configuration of one of the Br atoms was previously assigned via NMR correlations and has now been confirmed by the geometry of the solid-state structure. The compound features a Br—C—C—Br torsion angle of 66.68 (12)°, whereby the C atoms in the calculation are respectively sp³- and sp²-hybridized.

Related literature

For the structure of a closely related tribromide compound, see: Hökelek et al. (1991 ). For other similar solid-state structures based on a homobenzonorbornadiene framework, see: Daştan et al. (1994 ); Balci et al. (1996 ); Mangion et al. (2001 ). For synthesis of the title compound, see: Kitahonoki et al. (1969 ). For derivatization, see: Çakmak & Balci (1989 ); Bender et al. (2003 ).

Experimental

Crystal data

C₁₂H₁₀Br₂
M_r = 314.02
Triclinic, $[P \overline 1]$
a = 6.8554 (5) Å
b = 8.0926 (6) Å
c = 10.1024 (7) Å
α = 78.936 (1)°
β = 78.867 (1)°
γ = 83.665 (1)°
V = 538.13 (7) Å³
Z = 2
Mo Kα radiation
μ = 7.49 mm⁻¹
T = 173 K
0.37 × 0.36 × 0.09 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2008 ) T_min = 0.497, T_max = 0.746
6108 measured reflections
2354 independent reflections
2240 reflections with I > 2σ(I)
R_int = 0.013

Refinement

R[F² > 2σ(F²)] = 0.016
wR(F²) = 0.040
S = 1.03
2354 reflections
128 parameters
H-atom parameters constrained
Δρ_max = 0.58 e Å⁻³
Δρ_min = −0.45 e Å⁻³

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT-Plus (Bruker, 2008); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001 ); software used to prepare material for publication: publCIF (Westrip, 2010 ).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811041730/pv2455sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811041730/pv2455Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536811041730/pv2455Isup3.cml

checkCIF report

Comment top

In the title molecule (1) ( Fig. 1), an exo-configuration of Br2, which was originally assigned from NMR correlations (Kitahonoki et al., 1969), has now been confirmed by the X-ray data. As such, the stereochemistry of the two enantiomers that assemble in each unit cell can be unambiguously assigned as RRR and SSS (Fig. 2).

A dihedral angle of 66.7 (1)° was calculated for the Br1—C10—C11—Br2 torsion between the exo-configured C11—Br2 and the sp² hybridized C10—Br1. Additionally, the compound contains a six-membered ring (C8—C9—C10—C11—C1—C12) that exhibits an interesting envelope-type conformation. This conformation matches that observed in other structures based on a homobenzonorbornadiene framework (Balci et al., 1996). The structure reported by Hokelek et al. (1991) differs from 1 only by the presence of a third bromine atom attached to C12 and directed towards the cyclohexene ring (i.e. replacing H12B). However, the precision in C-C bond distances in 1 is on average five times better resulting in a considerably more reliable geometry than that reported for the tribromide.

Compound 1 has proven to be a convenient starting material for the preparation of a variety of substituted benzobarrelenes (Cakmak & Balci, 1989). For example, 1 can be readily converted to 2-bromo-3-deuteriobenzobarrelene (2) over several synthetic steps (Bender et al., 2003) as outlined in Figure 3.

Related literature top

For the structure of a closely related tribromide compound, see: Hokelek et al. (1991). For other similar solid-state structures based on a homobenzonorbornadiene framework, see: Dastan et al. (1994); Balci et al. (1996); Mangion et al. (2001). For synthesis of the title compound, see: Kitahonoki et al. (1969). For derivatization, see: Cakmak & Balci (1989); Bender et al. (2003).

Experimental top

The dibromide (1) was prepared in a one-step process (Kitahonoki et al., 1969) from the addition of dibromocarbene to benzonorbornadiene (3, Figure 3). The desired compound (1, m.p. 355-356 K) was obtained in 27% yield from the reaction mixture by distillation under reduced pressure and recrystallization from acetone-pentane.

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: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top

	Fig. 1. A view of 1 plotted with displacement ellipsoids drawn at the 50% probability level. H atoms are shown as spheres of arbitrary radius.
	Fig. 2. The centrosymmetric pair of enantiomers (SSS and RRR) depicted in a packing diagram.
	Fig. 3. Synthesis of exo-3,4-dibromo-6,7-benzobicyclo[3.2.1]octa-2,6-diene (1) and its conversion to 2-bromo-3-deuteriobenzobarrelene (2).

10,11-dibromotricyclo[6.3.1.0^2,7]dodeca-2,4,6,9-tetraene top

Crystal data top

C₁₂H₁₀Br₂	Z = 2
M_r = 314.02	F(000) = 304
Triclinic, P1	D_x = 1.938 Mg m⁻³
Hall symbol: -P 1	Melting point = 355–356 K
a = 6.8554 (5) Å	Mo Kα radiation, λ = 0.71073 Å
b = 8.0926 (6) Å	Cell parameters from 4757 reflections
c = 10.1024 (7) Å	θ = 2.6–27.6°
α = 78.936 (1)°	µ = 7.49 mm⁻¹
β = 78.867 (1)°	T = 173 K
γ = 83.665 (1)°	Plate, colourless
V = 538.13 (7) Å³	0.37 × 0.36 × 0.09 mm

Data collection top

Bruker APEXII CCD area-detector diffractometer	2354 independent reflections
Radiation source: fine-focus sealed tube	2240 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.013
Detector resolution: 66.06 pixels mm^-1	θ_max = 27.1°, θ_min = 2.1°
ϕ and ω scans	h = −8→8
Absorption correction: multi-scan (SADABS; Bruker, 2008)	k = −10→10
T_min = 0.497, T_max = 0.746	l = −12→12
6108 measured reflections

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.016	H-atom parameters constrained
wR(F²) = 0.040	w = 1/[σ²(F_o²) + (0.0181P)² + 0.3469P] where P = (F_o² + 2F_c²)/3
S = 1.03	(Δ/σ)_max = 0.001
2354 reflections	Δρ_max = 0.58 e Å⁻³
128 parameters	Δρ_min = −0.45 e Å⁻³
0 restraints	Extinction correction: SHELXTL (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: heavy-atom method	Extinction coefficient: 0.0205 (9)

Crystal data top

C₁₂H₁₀Br₂	γ = 83.665 (1)°
M_r = 314.02	V = 538.13 (7) Å³
Triclinic, P1	Z = 2
a = 6.8554 (5) Å	Mo Kα radiation
b = 8.0926 (6) Å	µ = 7.49 mm⁻¹
c = 10.1024 (7) Å	T = 173 K
α = 78.936 (1)°	0.37 × 0.36 × 0.09 mm
β = 78.867 (1)°

Data collection top

Bruker APEXII CCD area-detector diffractometer	2354 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2008)	2240 reflections with I > 2σ(I)
T_min = 0.497, T_max = 0.746	R_int = 0.013
6108 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.016	0 restraints
wR(F²) = 0.040	H-atom parameters constrained
S = 1.03	Δρ_max = 0.58 e Å⁻³
2354 reflections	Δρ_min = −0.45 e Å⁻³
128 parameters

Special details top

Experimental. A crystal coated in Paratone (TM) oil was mounted on the end of a thin glass fiber and cooled in the gas stream of the diffractometer Kryoflex low temperature device.

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

	x	y	z	U_iso*/U_eq
Br1	0.21938 (3)	0.19786 (2)	0.215988 (17)	0.02899 (7)
Br2	0.61510 (3)	0.37752 (2)	0.314452 (18)	0.03298 (7)
C10	0.2653 (2)	0.43063 (19)	0.19221 (16)	0.0202 (3)
C9	0.2194 (2)	0.5361 (2)	0.08314 (16)	0.0210 (3)
H9	0.1728	0.4944	0.0141	0.025*
C11	0.3411 (2)	0.48460 (19)	0.30557 (16)	0.0206 (3)
H11	0.2516	0.4464	0.3944	0.025*
C7	0.0743 (2)	0.79247 (18)	0.17148 (15)	0.0193 (3)
C1	0.3474 (2)	0.67785 (19)	0.28318 (16)	0.0198 (3)
H1	0.4275	0.7135	0.3443	0.024*
C2	0.1358 (2)	0.76059 (18)	0.29894 (15)	0.0188 (3)
C12	0.4241 (2)	0.7434 (2)	0.13037 (16)	0.0224 (3)
H12A	0.4561	0.8627	0.1142	0.027*
H12B	0.5428	0.6735	0.0938	0.027*
C8	0.2415 (2)	0.72350 (19)	0.06857 (16)	0.0209 (3)
H8	0.2463	0.7860	−0.0274	0.025*
C5	−0.2360 (2)	0.9194 (2)	0.27206 (18)	0.0246 (3)
H5	−0.3634	0.9756	0.2636	0.029*
C3	0.0114 (2)	0.8056 (2)	0.41336 (16)	0.0224 (3)
H3	0.0520	0.7817	0.5002	0.027*
C4	−0.1757 (2)	0.8871 (2)	0.39833 (17)	0.0254 (3)
H4	−0.2624	0.9208	0.4755	0.030*
C6	−0.1118 (2)	0.8703 (2)	0.15684 (17)	0.0225 (3)
H6	−0.1544	0.8901	0.0707	0.027*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br1	0.04010 (11)	0.01927 (9)	0.02778 (10)	−0.00622 (7)	−0.00221 (7)	−0.00608 (6)
Br2	0.03114 (11)	0.03503 (11)	0.03414 (11)	0.01206 (7)	−0.01449 (7)	−0.00890 (7)
C10	0.0213 (7)	0.0171 (7)	0.0224 (7)	−0.0028 (6)	−0.0008 (6)	−0.0064 (6)
C9	0.0197 (7)	0.0237 (8)	0.0207 (7)	−0.0012 (6)	−0.0027 (6)	−0.0078 (6)
C11	0.0213 (7)	0.0206 (7)	0.0197 (7)	0.0022 (6)	−0.0047 (6)	−0.0040 (6)
C7	0.0222 (7)	0.0155 (7)	0.0200 (7)	−0.0026 (6)	−0.0032 (6)	−0.0028 (5)
C1	0.0188 (7)	0.0206 (7)	0.0214 (7)	−0.0012 (6)	−0.0047 (6)	−0.0057 (6)
C2	0.0197 (7)	0.0156 (7)	0.0216 (7)	−0.0022 (5)	−0.0037 (6)	−0.0036 (5)
C12	0.0204 (7)	0.0217 (8)	0.0241 (8)	−0.0029 (6)	−0.0003 (6)	−0.0041 (6)
C8	0.0233 (8)	0.0206 (7)	0.0176 (7)	−0.0005 (6)	−0.0026 (6)	−0.0021 (6)
C5	0.0189 (7)	0.0211 (8)	0.0334 (9)	−0.0001 (6)	−0.0045 (6)	−0.0048 (6)
C3	0.0254 (8)	0.0218 (8)	0.0206 (7)	−0.0027 (6)	−0.0038 (6)	−0.0052 (6)
C4	0.0239 (8)	0.0240 (8)	0.0270 (8)	−0.0019 (6)	0.0022 (6)	−0.0079 (6)
C6	0.0234 (8)	0.0199 (7)	0.0250 (8)	−0.0019 (6)	−0.0075 (6)	−0.0026 (6)

Geometric parameters (Å, º) top

Br1—C10	1.9061 (15)	C1—H1	1.0000
Br2—C11	1.9908 (15)	C2—C3	1.382 (2)
C10—C9	1.325 (2)	C12—C8	1.539 (2)
C10—C11	1.498 (2)	C12—H12A	0.9900
C9—C8	1.517 (2)	C12—H12B	0.9900
C9—H9	0.9500	C8—H8	1.0000
C11—C1	1.541 (2)	C5—C4	1.385 (2)
C11—H11	1.0000	C5—C6	1.399 (2)
C7—C6	1.380 (2)	C5—H5	0.9500
C7—C2	1.400 (2)	C3—C4	1.397 (2)
C7—C8	1.526 (2)	C3—H3	0.9500
C1—C2	1.521 (2)	C4—H4	0.9500
C1—C12	1.541 (2)	C6—H6	0.9500

C9—C10—C11	123.77 (14)	C8—C12—C1	100.48 (12)
C9—C10—Br1	119.62 (12)	C8—C12—H12A	111.7
C11—C10—Br1	116.49 (11)	C1—C12—H12A	111.7
C10—C9—C8	119.94 (14)	C8—C12—H12B	111.7
C10—C9—H9	120.0	C1—C12—H12B	111.7
C8—C9—H9	120.0	H12A—C12—H12B	109.4
C10—C11—C1	111.60 (13)	C9—C8—C7	107.28 (12)
C10—C11—Br2	109.24 (10)	C9—C8—C12	107.79 (13)
C1—C11—Br2	108.86 (10)	C7—C8—C12	100.49 (12)
C10—C11—H11	109.0	C9—C8—H8	113.4
C1—C11—H11	109.0	C7—C8—H8	113.4
Br2—C11—H11	109.0	C12—C8—H8	113.4
C6—C7—C2	120.87 (14)	C4—C5—C6	120.84 (15)
C6—C7—C8	131.24 (14)	C4—C5—H5	119.6
C2—C7—C8	107.87 (13)	C6—C5—H5	119.6
C2—C1—C11	109.58 (12)	C2—C3—C4	118.46 (15)
C2—C1—C12	100.65 (12)	C2—C3—H3	120.8
C11—C1—C12	108.97 (12)	C4—C3—H3	120.8
C2—C1—H1	112.3	C5—C4—C3	120.70 (15)
C11—C1—H1	112.3	C5—C4—H4	119.7
C12—C1—H1	112.3	C3—C4—H4	119.7
C3—C2—C7	120.78 (14)	C7—C6—C5	118.33 (15)
C3—C2—C1	130.10 (14)	C7—C6—H6	120.8
C7—C2—C1	109.11 (13)	C5—C6—H6	120.8

C11—C10—C9—C8	−0.4 (2)	C2—C1—C12—C8	−42.36 (14)
Br1—C10—C9—C8	175.59 (11)	C11—C1—C12—C8	72.80 (14)
C9—C10—C11—C1	3.2 (2)	C10—C9—C8—C7	−72.51 (18)
Br1—C10—C11—C1	−172.90 (10)	C10—C9—C8—C12	34.95 (19)
C9—C10—C11—Br2	−117.19 (15)	C6—C7—C8—C9	−95.45 (19)
Br1—C10—C11—Br2	66.68 (12)	C2—C7—C8—C9	82.96 (15)
C10—C11—C1—C2	68.38 (16)	C6—C7—C8—C12	152.03 (16)
Br2—C11—C1—C2	−170.97 (10)	C2—C7—C8—C12	−29.56 (15)
C10—C11—C1—C12	−40.88 (17)	C1—C12—C8—C9	−68.19 (14)
Br2—C11—C1—C12	79.77 (13)	C1—C12—C8—C7	43.94 (14)
C6—C7—C2—C3	0.3 (2)	C7—C2—C3—C4	−1.4 (2)
C8—C7—C2—C3	−178.29 (14)	C1—C2—C3—C4	177.45 (15)
C6—C7—C2—C1	−178.77 (14)	C6—C5—C4—C3	0.4 (2)
C8—C7—C2—C1	2.62 (16)	C2—C3—C4—C5	1.1 (2)
C11—C1—C2—C3	91.68 (19)	C2—C7—C6—C5	1.1 (2)
C12—C1—C2—C3	−153.62 (16)	C8—C7—C6—C5	179.37 (15)
C11—C1—C2—C7	−89.35 (15)	C4—C5—C6—C7	−1.5 (2)
C12—C1—C2—C7	25.36 (15)

Experimental details

Crystal data
Chemical formula	C₁₂H₁₀Br₂
M_r	314.02
Crystal system, space group	Triclinic, P1
Temperature (K)	173
a, b, c (Å)	6.8554 (5), 8.0926 (6), 10.1024 (7)
α, β, γ (°)	78.936 (1), 78.867 (1), 83.665 (1)
V (Å³)	538.13 (7)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	7.49
Crystal size (mm)	0.37 × 0.36 × 0.09

Data collection
Diffractometer	Bruker APEXII CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2008)
T_min, T_max	0.497, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections	6108, 2354, 2240
R_int	0.013
(sin θ/λ)_max (Å⁻¹)	0.641

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.016, 0.040, 1.03
No. of reflections	2354
No. of parameters	128
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.58, −0.45

Computer programs: APEX2 (Bruker, 2008), SAINT-Plus (Bruker, 2008), SHELXS97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008), X-SEED (Barbour, 2001), publCIF (Westrip, 2010).

Acknowledgements

Sherry Lawson and Douglas Dolman are thanked for the sample preparation. This research was supported by the Natural Sciences and Engineering Research Council (NSERC) of Canada. The diffractometer at the University of Lethbridge X-ray Diffraction Facility was purchased with the help of NSERC and the University of Lethbridge.

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