6H,12H-5,11-Methano­dibenzo[b,f][1,5]diazo­cine

In the mol­ecule of the title compound, C₁₅H₁₄N₂, the unsubstituted analogue of Tröger's base, the two aromatic rings are offset with respect to one another. The dihedral angle between the two benzene rings is 95.42 (4)°.

Key indicators

• Single-crystal X-ray study
• T = 150 K
• Mean [sigma](C-C)= 0.002 Å
• R factor = 0.038
• wR factor = 0.106
• Data-to-parameter ratio = 17.5

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S1. Comment

Tröger's base analogues are chiral, cavity-containing compounds with a V-shaped structure where two aromatic rings define the walls of the cavity. An important feature of all Tröger's base analogues is the methano-strapped diazocine bridge that imparts a twist within the compounds such that the two aryl rings are offset with respect to one another. The dihedral angle between these rings has been measured to lie between 82° (Solano et al., 2005) and 108.44 (4)° (Faroughi et al., 2006b) for simple dibenzo Tröger's base analogues, and is dependent upon the nature of the substituents on the aromatic rings. We have previously reported that the dihedral angles in 2,8-Dichloro and 2,8-dibromo Tröger's bases are 95.64 (3)° (Faroughi et al., 2007) and 94.45 (4)° (Faroughi et al., 2006a), respectively, and now report that the title compound, (I), has a very similar structure. Compound (I) is devoid of any substitutents and in the minimum energy conformation, the dihedral angle of this compound was calculated to be 101.33 ° (Pardo et al., 2006).

We were interested in preparing a range of dihalo Tröger's base analogues as precursors for supramolecular recognition elements. The synthesis of (I) in racemic form was achieved by hydrogenolysis of the 2,8-dibromo analogue.

In the molecule of the title compound, (I), (Fig. 1) the bond lengths and angles are within normal ranges (Allen et al., 1987). Rings B (N1/N2/C1/C6—C8) and C (N1/N2/C8/C9/C14/C15) are not planar, having total puckering amplitudes, Q_T, of 1.395 (3) and 0.668 (3) Å, respectively and twist conformations φ = -116.62 (3)°, θ = 109.90 (2)° and φ = -51.67 (3)°, θ = 113.44 (3)° (Cremer & Pople, 1975). Rings A (C1—C6) and D (C9—C14) are, of course, planar and the dihedral angle between them is 95.42 (4)°.

Related literature

For general background, see: Solano et al. (2005); Allen et al. (1987); Cremer & Pople (1975). For related literature, see: Pardo et al. (2006); Faroughi et al. (2006a,b); Faroughi et al. (2007); Cooper & Partridge (1955); Li et al. (2005); Jensen et al. (2002).

S2. Experimental

2,8-Dibromo-6H,12H-5,11-methanodibenzo[b,f][1,5] diazocine (5.0 g, 13.16 mmol) was dissolved in absolute ethanol (750 ml) and dichloromethane (200 ml). Palladium, 10 wt. % on activated carbon (0.2 g) was added and the mixture was stirred under hydrogen atmosphere in the dark for 7 d. The reaction mixture was washed through celite, evaporated to dryness to afford a pale yellow solid. The solid was dissolved in dichloromethane (450 ml), basified with sodium hydrogen carbonate (2 x 400 ml). The mixture was extracted into dichloromethane (2 x 100 ml). The combined organic layers were washed with brine (100 ml), dried over anhydrous sodium sulfate, filtered and evaporated to dryness to afford the title compound (yield; 2.86 g, 98%) as a white solid. No further purification was needed: m.p. 413.62 K (DSC) (411–412 K (Cooper & Partridge, 1955), 403–404 K (Li et al., 2005), 409.5–410 K (Jensen et al., 2002). Single crystals of (I) were produced from slow evaporation of a dichloromethane solution.

S3. Refinement

H atoms were positioned geometrically, with C—H = 0.95 and 0.99 Å for aromatic and methylene H atoms, respectively, and constrained to ride on their parent atoms, with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: X-SEED (Barbour, 2001) and SHELXTL (Bruker, 2003); software used to prepare material for publication: modiCIFer (Guzei, 2005).

Figures

	Fig. 1. The molecular structure of (I) with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. Preparation of the title compound.

6H,12H-5,11-Methanodibenzo[b,f][1,5]diazocine

Crystal data

C15H14N2	F(000) = 472
Mr = 222.28	Dx = 1.323 Mg m^−3
Monoclinic, P21/c	Melting point: 413 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 12.266 (2) Å	Cell parameters from 6144 reflections
b = 7.362 (1) Å	θ = 3.2–28.4°
c = 12.759 (2) Å	µ = 0.08 mm^−1
β = 104.457 (2)°	T = 150 K
V = 1115.7 (3) Å^3	Prism, colorless
Z = 4	0.50 × 0.50 × 0.42 mm

Data collection

Bruker SMART 1000 CCD area-detector diffractometer	2701 independent reflections
Radiation source: fine-focus sealed tube	2297 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.038
ω scans	θmax = 28.4°, θmin = 1.7°
Absorption correction: integration [Gaussian (Coppens et al., 1965) and XPREP (Siemens, 1995)]	h = −16→16
Tmin = 0.964, Tmax = 0.976	k = −9→9
10679 measured reflections	l = −16→16

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)] = 0.038	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.106	H-atom parameters constrained
S = 1.06	w = 1/[σ^2(Fo^2) + (0.0499P)^2 + 0.3391P] where P = (Fo^2 + 2Fc^2)/3
2701 reflections	(Δ/σ)max < 0.001
154 parameters	Δρmax = 0.32 e Å^−3
0 restraints	Δρmin = −0.15 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
N1	0.18891 (7)	0.28087 (13)	−0.03028 (7)	0.0219 (2)
N2	0.26653 (8)	0.18258 (13)	0.15515 (7)	0.0235 (2)
C1	0.15935 (8)	0.09549 (15)	−0.05815 (8)	0.0201 (2)
C2	0.12619 (9)	0.04813 (16)	−0.16752 (9)	0.0239 (2)
H2	0.1245	0.1383	−0.2212	0.029*
C3	0.09587 (9)	−0.12837 (17)	−0.19852 (9)	0.0280 (3)
H3	0.0740	−0.1591	−0.2732	0.034*
C4	0.09733 (9)	−0.26109 (16)	−0.12057 (10)	0.0286 (3)
H4	0.0766	−0.3826	−0.1415	0.034*
C5	0.12936 (9)	−0.21395 (16)	−0.01225 (10)	0.0263 (2)
H5	0.1288	−0.3041	0.0409	0.032*
C6	0.16238 (8)	−0.03768 (15)	0.02097 (9)	0.0216 (2)
C7	0.20637 (9)	0.00762 (16)	0.13997 (9)	0.0257 (2)
H7A	0.1426	0.0132	0.1745	0.031*
H7B	0.2580	−0.0898	0.1759	0.031*
C8	0.19490 (9)	0.31378 (16)	0.08392 (9)	0.0250 (2)
H8A	0.2245	0.4376	0.1034	0.030*
H8B	0.1181	0.3080	0.0953	0.030*
C9	0.37554 (9)	0.17298 (15)	0.13212 (8)	0.0213 (2)
C10	0.46315 (9)	0.08515 (16)	0.20605 (9)	0.0262 (2)
H10	0.4491	0.0277	0.2681	0.031*
C11	0.57021 (10)	0.08172 (17)	0.18908 (10)	0.0294 (3)
H11	0.6292	0.0203	0.2390	0.035*
C12	0.59195 (9)	0.16755 (17)	0.09953 (10)	0.0285 (3)
H12	0.6661	0.1691	0.0895	0.034*
C13	0.50467 (10)	0.25091 (15)	0.02499 (9)	0.0252 (2)
H13	0.5194	0.3079	−0.0368	0.030*
C14	0.39554 (9)	0.25259 (14)	0.03911 (9)	0.0211 (2)
C15	0.29950 (9)	0.33096 (15)	−0.04816 (9)	0.0236 (2)
H15A	0.3063	0.4649	−0.0485	0.028*
H15B	0.3047	0.2854	−0.1198	0.028*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0195 (4)	0.0218 (5)	0.0237 (4)	0.0013 (3)	0.0043 (3)	0.0017 (3)
N2	0.0222 (5)	0.0278 (5)	0.0210 (4)	0.0018 (4)	0.0060 (3)	−0.0004 (4)
C1	0.0140 (4)	0.0230 (5)	0.0235 (5)	0.0017 (4)	0.0050 (4)	0.0007 (4)
C2	0.0191 (5)	0.0295 (6)	0.0224 (5)	0.0020 (4)	0.0038 (4)	0.0023 (4)
C3	0.0206 (5)	0.0356 (6)	0.0265 (5)	0.0005 (5)	0.0032 (4)	−0.0069 (5)
C4	0.0194 (5)	0.0254 (6)	0.0400 (7)	−0.0016 (4)	0.0055 (4)	−0.0056 (5)
C5	0.0207 (5)	0.0251 (6)	0.0336 (6)	−0.0001 (4)	0.0077 (4)	0.0049 (5)
C6	0.0161 (5)	0.0256 (5)	0.0239 (5)	0.0009 (4)	0.0064 (4)	0.0020 (4)
C7	0.0254 (5)	0.0304 (6)	0.0223 (5)	−0.0017 (4)	0.0081 (4)	0.0042 (4)
C8	0.0223 (5)	0.0264 (6)	0.0260 (5)	0.0041 (4)	0.0057 (4)	−0.0032 (4)
C9	0.0205 (5)	0.0212 (5)	0.0215 (5)	0.0005 (4)	0.0040 (4)	−0.0030 (4)
C10	0.0276 (6)	0.0273 (6)	0.0217 (5)	0.0018 (4)	0.0025 (4)	0.0013 (4)
C11	0.0234 (5)	0.0287 (6)	0.0317 (6)	0.0045 (5)	−0.0014 (4)	0.0001 (5)
C12	0.0188 (5)	0.0276 (6)	0.0387 (6)	0.0004 (4)	0.0063 (5)	−0.0028 (5)
C13	0.0231 (5)	0.0236 (6)	0.0296 (6)	−0.0026 (4)	0.0078 (4)	0.0001 (4)
C14	0.0202 (5)	0.0183 (5)	0.0237 (5)	−0.0003 (4)	0.0034 (4)	−0.0009 (4)
C15	0.0210 (5)	0.0233 (5)	0.0256 (5)	−0.0015 (4)	0.0041 (4)	0.0051 (4)

Geometric parameters (Å, º)

N1—C1	1.4340 (14)	C7—H7A	0.9900
N1—C8	1.4607 (14)	C7—H7B	0.9900
N1—C15	1.4774 (13)	C8—H8A	0.9900
N2—C9	1.4406 (13)	C8—H8B	0.9900
N2—C8	1.4602 (14)	C9—C10	1.3988 (15)
N2—C7	1.4730 (15)	C9—C14	1.3990 (15)
C1—C2	1.3967 (15)	C10—C11	1.3835 (16)
C1—C6	1.4010 (15)	C10—H10	0.9500
C2—C3	1.3819 (17)	C11—C12	1.3885 (17)
C2—H2	0.9500	C11—H11	0.9500
C3—C4	1.3911 (18)	C12—C13	1.3853 (16)
C3—H3	0.9500	C12—H12	0.9500
C4—C5	1.3834 (17)	C13—C14	1.3945 (15)
C4—H4	0.9500	C13—H13	0.9500
C5—C6	1.3936 (16)	C14—C15	1.5184 (14)
C5—H5	0.9500	C15—H15A	0.9900
C6—C7	1.5161 (15)	C15—H15B	0.9900
C1—N1—C8	110.60 (9)	N2—C8—N1	112.56 (9)
C1—N1—C15	112.60 (8)	N2—C8—H8A	109.1
C8—N1—C15	107.05 (8)	N1—C8—H8A	109.1
C9—N2—C8	110.51 (9)	N2—C8—H8B	109.1
C9—N2—C7	112.97 (9)	N1—C8—H8B	109.1
C8—N2—C7	107.02 (9)	H8A—C8—H8B	107.8
C2—C1—C6	119.60 (10)	C10—C9—C14	119.85 (10)
C2—C1—N1	118.55 (9)	C10—C9—N2	118.75 (10)
C6—C1—N1	121.85 (9)	C14—C9—N2	121.38 (9)
C3—C2—C1	120.74 (10)	C11—C10—C9	120.16 (11)
C3—C2—H2	119.6	C11—C10—H10	119.9
C1—C2—H2	119.6	C9—C10—H10	119.9
C2—C3—C4	120.08 (11)	C10—C11—C12	120.34 (10)
C2—C3—H3	120.0	C10—C11—H11	119.8
C4—C3—H3	120.0	C12—C11—H11	119.8
C5—C4—C3	119.20 (11)	C13—C12—C11	119.50 (10)
C5—C4—H4	120.4	C13—C12—H12	120.3
C3—C4—H4	120.4	C11—C12—H12	120.3
C4—C5—C6	121.73 (11)	C12—C13—C14	121.16 (10)
C4—C5—H5	119.1	C12—C13—H13	119.4
C6—C5—H5	119.1	C14—C13—H13	119.4
C5—C6—C1	118.62 (10)	C13—C14—C9	118.89 (10)
C5—C6—C7	120.88 (10)	C13—C14—C15	120.17 (9)
C1—C6—C7	120.43 (10)	C9—C14—C15	120.86 (9)
N2—C7—C6	111.43 (9)	N1—C15—C14	111.48 (9)
N2—C7—H7A	109.3	N1—C15—H15A	109.3
C6—C7—H7A	109.3	C14—C15—H15A	109.3
N2—C7—H7B	109.3	N1—C15—H15B	109.3
C6—C7—H7B	109.3	C14—C15—H15B	109.3
H7A—C7—H7B	108.0	H15A—C15—H15B	108.0
C8—N1—C1—C2	166.47 (9)	C1—N1—C8—N2	51.79 (12)
C15—N1—C1—C2	−73.82 (11)	C15—N1—C8—N2	−71.21 (11)
C8—N1—C1—C6	−13.21 (13)	C8—N2—C9—C10	166.53 (10)
C15—N1—C1—C6	106.51 (11)	C7—N2—C9—C10	−73.59 (12)
C6—C1—C2—C3	0.29 (15)	C8—N2—C9—C14	−12.12 (14)
N1—C1—C2—C3	−179.39 (9)	C7—N2—C9—C14	107.76 (11)
C1—C2—C3—C4	0.47 (16)	C14—C9—C10—C11	2.00 (16)
C2—C3—C4—C5	0.02 (16)	N2—C9—C10—C11	−176.68 (10)
C3—C4—C5—C6	−1.30 (16)	C9—C10—C11—C12	0.95 (18)
C4—C5—C6—C1	2.04 (16)	C10—C11—C12—C13	−2.43 (18)
C4—C5—C6—C7	−174.88 (10)	C11—C12—C13—C14	0.98 (17)
C2—C1—C6—C5	−1.51 (15)	C12—C13—C14—C9	1.92 (16)
N1—C1—C6—C5	178.16 (9)	C12—C13—C14—C15	−174.93 (10)
C2—C1—C6—C7	175.42 (9)	C10—C9—C14—C13	−3.39 (15)
N1—C1—C6—C7	−4.91 (15)	N2—C9—C14—C13	175.25 (10)
C9—N2—C7—C6	−73.65 (11)	C10—C9—C14—C15	173.43 (10)
C8—N2—C7—C6	48.21 (11)	N2—C9—C14—C15	−7.93 (15)
C5—C6—C7—N2	163.19 (9)	C1—N1—C15—C14	−75.25 (11)
C1—C6—C7—N2	−13.68 (13)	C8—N1—C15—C14	46.50 (11)
C9—N2—C8—N1	52.38 (12)	C13—C14—C15—N1	166.32 (9)
C7—N2—C8—N1	−71.01 (11)	C9—C14—C15—N1	−10.46 (14)