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Acta Crystallogr Sect E Struct Rep Online. 2008 September 1; 64(Pt 9): o1797.
Published online 2008 August 20. doi:  10.1107/S1600536808026226
PMCID: PMC2960512

2,8-Dibromo-4,10-dichloro-6H,12H-5,11-methano­dibenzo[b,f][1,5]diazo­cine

Abstract

The title compound, C15H10Br2Cl2N2, a 2,8-dibromo-4,10-dichloro Tröger’s base analogue derived from 4-bromo-2-chloro­aniline, has a dihedral angle of 110.9 (10)° between the two aryl rings, the largest yet measured for a simple dibenzo analogue.

Related literature

For related literature on the synthesis and crystal structures of dihalogenated Tröger’s base analogues, see: Jensen & Wärnmark (2001 [triangle]); Faroughi et al. (2006a [triangle], 2007a [triangle],b [triangle]). For Tröger’s base analogues substituted with multiple electron-withdrawing groups, see: Faroughi et al. (2006b [triangle]); Bhuiyan et al. (2006 [triangle], 2007 [triangle]); Vande Velde et al. (2008 [triangle]). For reactions of halogenated Tröger’s base analogues, see: Jensen et al. (2002 [triangle]); Hof et al. (2005 [triangle]). For literature on racemization of Tröger’s base analogues and the effect of substituents ortho to the diazo­cine N atoms, see: Lenev et al. (2006 [triangle]).

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Object name is e-64-o1797-scheme1.jpg

Experimental

Crystal data

  • C15H10Br2Cl2N2
  • M r = 449.0
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-64-o1797-efi1.jpg
  • a = 7.910 (2) Å
  • b = 12.601 (3) Å
  • c = 15.230 (4) Å
  • V = 1518.0 (7) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 5.64 mm−1
  • T = 294 K
  • 0.30 × 0.12 × 0.07 mm

Data collection

  • Enraf–Nonius CAD-4 diffractometer
  • Absorption correction: analytical (de Meulenaer & Tompa, 1965 [triangle]) T min = 0.52, T max = 0.69
  • 1394 measured reflections
  • 1394 independent reflections
  • 1028 reflections with I > 2σ(I)
  • 1 standard reflection frequency: 30 min intensity decay: none

Refinement

  • R[F 2 > 2σ(F 2)] = 0.056
  • wR(F 2) = 0.061
  • S = 1.61
  • 1394 reflections
  • 189 parameters
  • H-atom parameters constrained
  • Δρmax = 0.98 e Å−3
  • Δρmin = −1.02 e Å−3
  • Absolute structure: Flack (1983 [triangle])
  • Flack parameter: 0.09 (2)

Data collection: CAD-4 (Schagen et al., 1989 [triangle]); cell refinement: CAD-4; data reduction: local program; program(s) used to solve structure: SIR92 (Altomare et al., 1994 [triangle]); program(s) used to refine structure: RAELS (Rae, 1996 [triangle]); molecular graphics: ORTEPII (Johnson, 1976 [triangle]); software used to prepare material for publication: local programs.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808026226/tk2290sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808026226/tk2290Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

The authors thank Macquarie University for the award of a Macquarie University Research Development Grant to ACT.

supplementary crystallographic information

Comment

Tröger's base analogues bearing electron-withdrawing groups were long thought to be difficult, if not impossible, to prepare. However, the synthesis of dihalogenated (Jensen & Wärnmark, 2001), octafluoro (Vande Velde et al., 2008) and tetranitro (Bhuiyan et al., 2007) Tröger's base analogues highlight the possiblities that now exist in terms of incorporating electron-withdrawing groups on the starting anilines. The synthetic utility of halogen-substituted Tröger's base analogue has been demonstrated with their conversion to alkyne- (Jensen & Wärnmark, 2001; Jensen et al., 2002) and functionalized phenyl- (Hof et al., 2005) substituted analogues, among others. It is noteworthy that crystal structures of several other 2,4,8,10-tetrasubstituted Tröger's base analogues exhibit large dihedral angles that are close to that in (I). Tröger's base analogues are known to undergo racemization in acidic solution, however the presence of a substituent at the ortho-position, relative to the bridge nitrogen atoms, has been shown to increase the racemization barrier (Lenev et al., 2006).

The molecular structure of (I) is shown in Fig. 1 and it was prepared as outlined in Fig. 2.

Experimental

4-Bromo-2-chloroaniline (1 g, 4.84 mmol) and paraformaldehyde (232 mg, 7.74 mmol) were added to an ice-cold solution of trifluoroacetic acid (10 ml). The reaction mixture was then stirred in dark at room temperature for 7 days under an atmosphere of argon. The ice-cold reaction mixture was basified by the dropwise addition of a mixture of ammonia (28%, 20 ml) and water (40 ml), followed by the additon of a saturated sodium hydrogen carbonate solution (20 ml). The resultant mixture was then extracted with dichloromethane (3 x 20 ml) and the combined organic layers were washed with brine (40 ml), dried over anhydrous sodium sulfate, filtered and evaporated to dryness. The crude product was chromatographed (silica gel, dichloromethane:hexane 8:2) to afford 2,8-dibromo-4,10-dichloro-6H,12H-5,11-methanodibenzo [b,f][1,5]diazocine (I) (613 mg, 56%) as a white solid and as a racemic mixture: m.p. 471–472 K; 1H NMR (400 MHz, CDCl3) δ 4.21–4.33 (4H, m), 4.55 (2H, d, J 17.3 Hz), 7.04 (2H, d, J 2.1 Hz), 7.41 (2H, d, J 2.1 Hz); 13C NMR (100 MHz, CDCl3) δ 54.37, 67.32, 117.15, 128.49, 130.17, 131.02, 131.71, 142.33. Analysis found: C 40.46; H 2.22; N 6.46; C15H10Br2Cl2N2 requires C 40.13; H 2.25; N 6.24. Single crystals were obtained from slow evaporation from dichloromethane solution of (I).

Refinement

Hydrogen atoms were included in positions calculated each cycle (C—H = 1.0 Å), and were assigned thermal parameters equal to their bonded atom. The maximum and minimum electron density peaks were located 0.73 and 1.20Å from the Cl2 and Br1 atoms, respectively.

Figures

Fig. 1.
ORTEPII (Johnson, 1976) plot of (I), with ellipsoids at the 10% probability level. H atoms are drawn as spheres of arbitrary radius.
Fig. 2.
Synthetic scheme for the synthesis of (I) showing the numbering system used in naming the compound.

Crystal data

C15H10Br2Cl2N2Dx = 1.96 Mg m3
Mr = 449.0Melting point: 471 K
Orthorhombic, Pca21Mo Kα radiation λ = 0.71073 Å
Hall symbol: P 2c -2acCell parameters from 11 reflections
a = 7.910 (2) Åθ = 10–11º
b = 12.601 (3) ŵ = 5.64 mm1
c = 15.230 (4) ÅT = 294 K
V = 1518.0 (7) Å3Prism, colourless
Z = 40.30 × 0.12 × 0.07 mm
F000 = 872.0

Data collection

Enraf–Nonius CAD-4 diffractometerθmax = 25º
ω–2θ scansh = 0→9
Absorption correction: analyticalde Meulenaer & Tompa (1965)k = 0→14
Tmin = 0.52, Tmax = 0.69l = −18→0
1394 measured reflections1 standard reflections
1394 independent reflections every 30 min
1028 reflections with I > 2σ(I) intensity decay: none

Refinement

Refinement on F  w = 1/[σ2(F) + 0.0004F2]
R[F2 > 2σ(F2)] = 0.056(Δ/σ)max = 0.002
wR(F2) = 0.061Δρmax = 0.98 e Å3
S = 1.61Δρmin = −1.02 e Å3
1394 reflectionsExtinction correction: none
189 parametersAbsolute structure: Flack (1983), 0 Friedel pairs
H-atom parameters constrainedFlack parameter: 0.09 (2)

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

xyzUiso*/Ueq
Br10.8061 (2)0.6867 (1)0.3991 (1)0.0585 (5)
Br20.2324 (2)0.0800 (1)0.0428 (2)0.0527 (5)
Cl10.9770 (5)0.5167 (4)0.0779 (3)0.057 (1)
Cl20.5654 (5)0.0565 (3)0.3603 (3)0.052 (1)
N10.9460 (14)0.3064 (10)0.1658 (8)0.041 (3)
N20.8319 (15)0.1842 (9)0.2739 (8)0.044 (3)
C10.9798 (19)0.2123 (12)0.2198 (10)0.044 (4)
C20.8998 (18)0.3929 (12)0.2193 (10)0.043 (4)
C30.8445 (18)0.3790 (11)0.3054 (8)0.041 (4)
C40.817 (2)0.2693 (12)0.3414 (8)0.049 (4)
C50.6842 (19)0.1696 (11)0.2226 (9)0.039 (4)
C60.6740 (19)0.2086 (11)0.1360 (9)0.036 (4)
C70.8206 (17)0.2753 (12)0.0978 (9)0.040 (4)
C80.9155 (17)0.4984 (13)0.1855 (9)0.043 (4)
C90.8825 (19)0.5861 (12)0.2397 (11)0.048 (4)
C100.839 (2)0.5684 (13)0.3247 (11)0.050 (4)
C110.818 (2)0.4666 (13)0.3570 (10)0.056 (4)
C120.5565 (17)0.1082 (10)0.2538 (8)0.031 (3)
C130.4158 (17)0.0854 (10)0.2036 (8)0.035 (3)
C140.4117 (17)0.1221 (11)0.1168 (9)0.040 (4)
C150.5433 (19)0.1819 (10)0.0853 (9)0.034 (3)
H1C11.07800.22730.25930.044
H2C11.00780.15130.18040.044
H1C40.70080.26600.36740.049
H2C40.90270.25590.38830.049
H1C70.77260.34100.07080.040
H2C70.87940.23260.05170.040
HC90.89060.66000.21620.048
HC110.78250.45670.41950.056
HC130.31940.04380.22860.035
HC150.54110.20610.02280.034

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Br10.060 (1)0.060 (1)0.0549 (9)−0.0011 (8)−0.001 (1)−0.0138 (9)
Br20.0470 (9)0.0650 (9)0.0461 (8)−0.0118 (8)−0.0026 (9)−0.0091 (9)
Cl10.061 (3)0.066 (3)0.044 (2)−0.019 (2)0.010 (2)0.000 (2)
Cl20.063 (3)0.056 (2)0.037 (2)0.000 (2)0.006 (2)0.018 (2)
N10.029 (7)0.058 (8)0.037 (7)0.001 (6)0.002 (6)−0.003 (6)
N20.046 (7)0.048 (7)0.038 (7)0.004 (6)−0.009 (6)0.020 (6)
C10.029 (9)0.067 (9)0.036 (8)0.005 (8)−0.016 (7)0.012 (8)
C20.051 (9)0.043 (9)0.034 (8)0.009 (8)0.020 (8)−0.006 (7)
C30.045 (9)0.059 (9)0.019 (8)−0.012 (8)−0.004 (7)−0.005 (7)
C40.083 (9)0.053 (8)0.013 (7)0.004 (9)−0.006 (7)0.007 (7)
C50.048 (9)0.043 (9)0.026 (7)0.000 (7)0.013 (7)0.007 (7)
C60.039 (8)0.042 (8)0.026 (8)0.010 (8)0.002 (6)−0.006 (7)
C70.037 (8)0.052 (9)0.030 (8)−0.007 (8)0.007 (7)−0.002 (7)
C80.029 (8)0.062 (9)0.039 (9)−0.002 (8)−0.002 (7)0.004 (9)
C90.047 (9)0.038 (9)0.059 (9)−0.010 (8)−0.001 (8)−0.007 (8)
C100.047 (9)0.057 (9)0.046 (9)−0.005 (8)0.017 (8)−0.007 (8)
C110.085 (9)0.052 (9)0.029 (8)−0.011 (9)0.009 (9)−0.007 (8)
C120.037 (8)0.032 (8)0.024 (7)0.009 (7)0.010 (6)−0.002 (6)
C130.046 (9)0.043 (9)0.016 (6)0.014 (8)0.001 (6)0.000 (7)
C140.029 (8)0.039 (8)0.052 (9)0.006 (7)0.010 (7)−0.015 (8)
C150.034 (8)0.039 (8)0.027 (7)0.004 (7)0.009 (7)−0.004 (7)

Geometric parameters (Å, °)

Br1—C101.890 (15)C4—H2C41.000
Br2—C141.888 (14)C5—C61.410 (18)
Cl1—C81.724 (14)C5—C121.358 (18)
Cl2—C121.750 (13)C6—C71.546 (20)
N1—C11.468 (18)C6—C151.333 (19)
N1—C21.409 (17)C7—H1C71.000
N1—C71.487 (18)C7—H2C71.000
N2—C11.474 (19)C8—C91.404 (20)
N2—C41.491 (18)C9—C101.357 (19)
N2—C51.417 (18)C9—HC91.000
C1—H1C11.000C10—C111.385 (21)
C1—H2C11.000C11—HC111.000
C2—C31.394 (18)C12—C131.381 (17)
C2—C81.431 (20)C13—C141.402 (18)
C3—C41.503 (20)C13—HC131.000
C3—C111.371 (20)C14—C151.371 (19)
C4—H1C41.000C15—HC151.000
C1—N1—C2110.4 (12)N1—C7—C6112.5 (11)
C1—N1—C7107.4 (11)N1—C7—H1C7108.7
C2—N1—C7115.7 (11)N1—C7—H2C7108.7
C1—N2—C4106.0 (11)C6—C7—H1C7108.7
C1—N2—C5112.2 (11)C6—C7—H2C7108.7
C4—N2—C5114.1 (12)H1C7—C7—H2C7109.5
N1—C1—N2111.3 (11)Cl1—C8—C2119.3 (11)
N1—C1—H1C1109.0Cl1—C8—C9120.4 (12)
N1—C1—H2C1109.0C2—C8—C9120.2 (12)
N2—C1—H1C1109.0C8—C9—C10118.6 (15)
N2—C1—H2C1109.0C8—C9—HC9120.7
H1C1—C1—H2C1109.5C10—C9—HC9120.7
N1—C2—C3121.9 (14)Br1—C10—C9118.5 (13)
N1—C2—C8119.2 (12)Br1—C10—C11120.0 (11)
C3—C2—C8118.8 (13)C9—C10—C11121.4 (15)
C2—C3—C4120.3 (13)C3—C11—C10121.6 (14)
C2—C3—C11119.1 (14)C3—C11—HC11119.2
C4—C3—C11120.6 (12)C10—C11—HC11119.2
N2—C4—C3113.5 (10)Cl2—C12—C5120.5 (12)
N2—C4—H1C4108.4Cl2—C12—C13117.9 (10)
N2—C4—H2C4108.4C5—C12—C13121.6 (13)
C3—C4—H1C4108.4C12—C13—C14118.2 (13)
C3—C4—H2C4108.4C12—C13—HC13120.9
H1C4—C4—H2C4109.5C14—C13—HC13120.9
N2—C5—C6121.2 (13)Br2—C14—C13119.2 (11)
N2—C5—C12119.6 (13)Br2—C14—C15121.0 (11)
C6—C5—C12118.9 (15)C13—C14—C15119.6 (13)
C5—C6—C7119.8 (13)C6—C15—C14121.6 (13)
C5—C6—C15119.9 (14)C6—C15—HC15119.2
C7—C6—C15120.1 (12)C14—C15—HC15119.2
C2—N1—C1—N257.5 (15)C2—C3—C11—C102.3 (24)
C2—N1—C1—H1C1−62.8C2—C3—C11—HC11−177.7
C2—N1—C1—H2C1177.8C4—C3—C11—C10−178.6 (16)
C7—N1—C1—N2−69.4 (15)C4—C3—C11—HC111.4
C7—N1—C1—H1C1170.3N2—C5—C6—C7−4.4 (20)
C7—N1—C1—H2C150.8N2—C5—C6—C15171.2 (13)
C1—N1—C2—C3−18.2 (18)C12—C5—C6—C7−177.9 (12)
C1—N1—C2—C8159.5 (13)C12—C5—C6—C15−2.3 (20)
C7—N1—C2—C3103.9 (16)N2—C5—C12—Cl25.4 (18)
C7—N1—C2—C8−78.3 (17)N2—C5—C12—C13−175.2 (12)
C1—N1—C7—C644.6 (15)C6—C5—C12—Cl2179.1 (10)
C1—N1—C7—H1C7165.1C6—C5—C12—C13−1.6 (20)
C1—N1—C7—H2C7−75.8C5—C6—C7—N1−10.2 (17)
C2—N1—C7—C6−79.1 (15)C5—C6—C7—H1C7−130.7
C2—N1—C7—H1C741.3C5—C6—C7—H2C7110.2
C2—N1—C7—H2C7160.4C15—C6—C7—N1174.2 (13)
C4—N2—C1—N1−69.8 (13)C15—C6—C7—H1C753.8
C4—N2—C1—H1C150.5C15—C6—C7—H2C7−65.3
C4—N2—C1—H2C1169.9C5—C6—C15—C143.9 (21)
C5—N2—C1—N155.3 (16)C5—C6—C15—HC15−176.1
C5—N2—C1—H1C1175.6C7—C6—C15—C14179.5 (12)
C5—N2—C1—H2C1−65.0C7—C6—C15—HC15−0.5
C1—N2—C4—C342.4 (15)Cl1—C8—C9—C10−178.1 (12)
C1—N2—C4—H1C4163.0Cl1—C8—C9—HC91.9
C1—N2—C4—H2C4−78.2C2—C8—C9—C101.4 (23)
C5—N2—C4—C3−81.5 (16)C2—C8—C9—HC9−178.6
C5—N2—C4—H1C439.1C8—C9—C10—Br1176.8 (11)
C5—N2—C4—H2C4157.9C8—C9—C10—C11−3.7 (25)
C1—N2—C5—C6−17.3 (19)HC9—C9—C10—Br1−3.2
C1—N2—C5—C12156.2 (13)HC9—C9—C10—C11176.3
C4—N2—C5—C6103.2 (14)Br1—C10—C11—C3−178.6 (12)
C4—N2—C5—C12−83.3 (16)Br1—C10—C11—HC111.4
N1—C2—C3—C4−5.9 (21)C9—C10—C11—C31.9 (26)
N1—C2—C3—C11173.3 (14)C9—C10—C11—HC11−178.1
C8—C2—C3—C4176.4 (14)Cl2—C12—C13—C14−176.9 (10)
C8—C2—C3—C11−4.4 (21)Cl2—C12—C13—HC133.1
N1—C2—C8—Cl14.3 (19)C5—C12—C13—C143.7 (19)
N1—C2—C8—C9−175.2 (13)C5—C12—C13—HC13−176.3
C3—C2—C8—Cl1−177.9 (11)C12—C13—C14—Br2173.5 (9)
C3—C2—C8—C92.6 (21)C12—C13—C14—C15−2.1 (18)
C2—C3—C4—N2−7.5 (20)HC13—C13—C14—Br2−6.5
C2—C3—C4—H1C4−128.1HC13—C13—C14—C15177.9
C2—C3—C4—H2C4113.1Br2—C14—C15—C6−177.3 (11)
C11—C3—C4—N2173.3 (14)Br2—C14—C15—HC152.7
C11—C3—C4—H1C452.7C13—C14—C15—C6−1.7 (20)
C11—C3—C4—H2C4−66.1C13—C14—C15—HC15178.3

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: TK2290).

References

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