6,6′-Dibromo-4,4′-dimethyl-3,3′-methyl­enebi(2H,4H-benz[e][1,3]oxazine)

In the title compound, C₁₉H₂₀Br₂N₂O₂, a crystallographic twofold rotation axis passes through the central C atom. The crystal structure is stabilized by weak C—H...N and inter­molecular C—H...O hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.033
• wR factor = 0.075
• Data-to-parameter ratio = 15.0

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT152_ALERT_1_C Supplied and Calc Volume s.u. Inconsistent .....          ?

Alert level G
PLAT793_ALERT_1_G Check the Absolute Configuration of C7     = ...          S

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
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S1. Comment

The title compound, (I), was prepared by reaction of racemic 2-(1-aminoethyl)-4-bromophenol, (II), with formaldehyde.

The molecule is centrosymmetric. The bond lengths observed in the two phenyl rings agree with eath other and are comparable with average values reported in the literature (Domenicano et al., 1975; Allen et al., 1987). The dihedral between the C1—C6 and C1a—C6a aromatic rings is 65.89 (2)°.

The molecules are linked via C—H···N hydrogen bonds into cyclic R²₂(6) dimers (Fig. 2). The hydrogen bonds observed in the structure are listed in Table 2.

Related literature

For related literature, see: Allen et al. (1987); Domenicano et al. (1975); Yang et al. (2005).

S2. Experimental

The title compound was prepared according to the procedure of Xiao-Feng Yang et al. (2005). A methanol solution (10 ml) of ammonia (0.9 mmol) and 1-(5-bromo-2-hydroxyphenyl)ethanone (0.9 mmol) wasreacted at room temperature for 24 h. After removal of the solvent, NaBH₄ (4.5 mmol) was added to the solution in THF/ethanol (20 ml; 1:1v/v) and stirred at 0°C until the solution became colorless. The solvent was removed under reduced pressure. Water (10 ml) was added to the residue and 1 N HCl was added dropwise until hydrogen production ceased. The mixture was neutralized with aqueous Na₂CO₃, then extracted with CHCl₃, and the organic layer was dried over anhydrous sodium sulfate. The solvent was removed under reduced pressure. Further purification was carried out by thin-layer silica-gel chromatography (chloroform) to give colorless solid (II), yield of 90.3%. The compound (II) was reacted with formaldehyde (1.2 equivalents) in a methanol solution (10 ml). Evaporation of a methanol solution at room temperature gave crystals of (I) (m.p.675–676 K) IR (KBr): 3443 (s), 2974 (m), 1481 (s), 1255 (s), 1178 (m), 970 (m), 628 (w) cm^-1.

S3. Refinement

All H atoms were positioned geometrically and treated as riding on their parent atoms, with C—H(methyl) = 0.96 Å, C—H(methylene) = 0.97 Å, C—H(methine) = 0.98 Å, C—H(aromatic) = 0.93 Å, and with U_iso(H) = 1.5U_eq(C_methyl) and 1.2U_eq(C_aromatic, C_methylene, C_methine ).

Computing details

Data collection: SMART (Bruker, 1996); cell refinement: SAINT; data reduction: SAINT (Bruker, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXTL (Bruker, 1997).

Figures

	Fig. 1. Compound (II).
	Fig. 2. The molecular structure of (I), showing the atom-labelling scheme.
	Fig. 3. A packing diagram of (I), dashed lines indicate hydrogen bonds.

6,6'-Dibromo-4,4'-dimethyl-3,3'-methylenebi(2H,4H- benz[e][1,3]oxazine)

Crystal data

C19H20Br2N2O2	F(000) = 936
Mr = 468.19	Dx = 1.670 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C2yc	Cell parameters from 1722 reflections
a = 19.826 (4) Å	θ = 2.0–25.5°
b = 11.702 (2) Å	µ = 4.37 mm^−1
c = 8.146 (2) Å	T = 298 K
β = 99.92 (3)°	Block, colourless
V = 1861.7 (6) Å^3	0.35 × 0.24 × 0.18 mm
Z = 4

Data collection

Bruker SMART CCD area-detector diffractometer	1722 independent reflections
Radiation source: fine-focus sealed tube	1375 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.037
ω scans	θmax = 25.5°, θmin = 2.0°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −24→24
Tmin = 0.298, Tmax = 0.459	k = −8→14
4729 measured reflections	l = −9→9

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)] = 0.033	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.075	H-atom parameters constrained
S = 1.08	w = 1/[σ^2(Fo^2) + (0.0208P)^2 + 3.2728P] where P = (Fo^2 + 2Fc^2)/3
1722 reflections	(Δ/σ)max = 0.001
115 parameters	Δρmax = 0.48 e Å^−3
0 restraints	Δρmin = −0.64 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	Occ. (<1)
C1	0.36058 (15)	0.8872 (3)	0.4372 (4)	0.0422 (7)
C2	0.30490 (16)	0.9531 (3)	0.4563 (4)	0.0505 (8)
H2	0.3107	1.0181	0.5230	0.061*
C3	0.24080 (16)	0.9226 (3)	0.3766 (4)	0.0500 (8)
H3	0.2028	0.9665	0.3881	0.060*
C4	0.23362 (15)	0.8261 (3)	0.2796 (4)	0.0441 (7)
C5	0.28870 (15)	0.7600 (3)	0.2608 (4)	0.0417 (7)
H5	0.2824	0.6952	0.1937	0.050*
C6	0.35394 (14)	0.7891 (3)	0.3412 (4)	0.0382 (7)
C7	0.41513 (14)	0.7178 (3)	0.3189 (4)	0.0411 (7)
H7	0.4123	0.7042	0.1993	0.049*
C8	0.41674 (18)	0.6022 (3)	0.4034 (5)	0.0614 (10)
H8A	0.4539	0.5578	0.3756	0.092*
H8B	0.3743	0.5631	0.3662	0.092*
H8C	0.4230	0.6126	0.5220	0.092*
C9	0.5000	0.8533 (4)	0.2500	0.0412 (10)
H9A	0.4622	0.9018	0.2008	0.049*	0.50
H9B	0.5378	0.9018	0.2992	0.049*	0.50
C10	0.47610 (15)	0.8379 (3)	0.5288 (4)	0.0479 (8)
H10A	0.5201	0.8735	0.5682	0.057*
H10B	0.4685	0.7815	0.6110	0.057*
Br1	0.145465 (16)	0.78480 (4)	0.16417 (5)	0.06290 (17)
N1	0.47908 (12)	0.7813 (2)	0.3773 (3)	0.0406 (6)
O1	0.42328 (10)	0.9242 (2)	0.5178 (3)	0.0512 (6)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0390 (16)	0.0488 (19)	0.0379 (17)	−0.0068 (14)	0.0040 (13)	−0.0015 (15)
C2	0.0505 (19)	0.0478 (19)	0.053 (2)	−0.0010 (16)	0.0093 (16)	−0.0110 (16)
C3	0.0413 (17)	0.054 (2)	0.055 (2)	0.0053 (15)	0.0099 (15)	0.0014 (17)
C4	0.0380 (16)	0.0527 (19)	0.0396 (17)	−0.0053 (14)	0.0014 (13)	0.0060 (15)
C5	0.0386 (16)	0.0472 (18)	0.0383 (17)	−0.0048 (14)	0.0035 (13)	−0.0033 (14)
C6	0.0379 (15)	0.0436 (17)	0.0330 (15)	−0.0043 (13)	0.0055 (12)	0.0012 (14)
C7	0.0360 (15)	0.0451 (18)	0.0408 (17)	−0.0030 (13)	0.0029 (13)	−0.0057 (14)
C8	0.052 (2)	0.047 (2)	0.085 (3)	−0.0017 (16)	0.0106 (18)	0.003 (2)
C9	0.037 (2)	0.045 (3)	0.040 (2)	0.000	0.0048 (18)	0.000
C10	0.0392 (16)	0.066 (2)	0.0357 (17)	−0.0054 (16)	−0.0022 (13)	−0.0020 (16)
Br1	0.03772 (19)	0.0865 (3)	0.0605 (3)	−0.00454 (18)	−0.00279 (15)	−0.0045 (2)
N1	0.0344 (12)	0.0502 (15)	0.0355 (14)	−0.0024 (11)	0.0015 (10)	−0.0022 (12)
O1	0.0392 (12)	0.0619 (15)	0.0511 (14)	−0.0078 (10)	0.0037 (10)	−0.0213 (11)

Geometric parameters (Å, º)

C1—O1	1.372 (3)	C7—C8	1.515 (4)
C1—C2	1.377 (4)	C7—H7	0.9800
C1—C6	1.383 (4)	C8—H8A	0.9600
C2—C3	1.371 (4)	C8—H8B	0.9600
C2—H2	0.9300	C8—H8C	0.9600
C3—C4	1.371 (5)	C9—N1^i	1.451 (4)
C3—H3	0.9300	C9—N1	1.451 (4)
C4—C5	1.368 (4)	C9—H9A	0.9700
C4—Br1	1.899 (3)	C9—H9B	0.9700
C5—C6	1.388 (4)	C10—N1	1.410 (4)
C5—H5	0.9300	C10—O1	1.447 (4)
C6—C7	1.509 (4)	C10—H10A	0.9700
C7—N1	1.476 (4)	C10—H10B	0.9700
O1—C1—C2	116.6 (3)	C8—C7—H7	107.5
O1—C1—C6	121.5 (3)	C7—C8—H8A	109.5
C2—C1—C6	121.9 (3)	C7—C8—H8B	109.5
C3—C2—C1	119.7 (3)	H8A—C8—H8B	109.5
C3—C2—H2	120.1	C7—C8—H8C	109.5
C1—C2—H2	120.1	H8A—C8—H8C	109.5
C4—C3—C2	118.9 (3)	H8B—C8—H8C	109.5
C4—C3—H3	120.5	N1^i—C9—N1	109.1 (3)
C2—C3—H3	120.5	N1^i—C9—H9A	109.9
C5—C4—C3	121.6 (3)	N1—C9—H9A	109.9
C5—C4—Br1	119.0 (2)	N1^i—C9—H9B	109.9
C3—C4—Br1	119.3 (2)	N1—C9—H9B	109.9
C4—C5—C6	120.3 (3)	H9A—C9—H9B	108.3
C4—C5—H5	119.8	N1—C10—O1	114.3 (2)
C6—C5—H5	119.8	N1—C10—H10A	108.7
C1—C6—C5	117.5 (3)	O1—C10—H10A	108.7
C1—C6—C7	121.8 (3)	N1—C10—H10B	108.7
C5—C6—C7	120.7 (3)	O1—C10—H10B	108.7
N1—C7—C6	110.3 (2)	H10A—C10—H10B	107.6
N1—C7—C8	110.7 (2)	C10—N1—C9	114.4 (3)
C6—C7—C8	113.2 (3)	C10—N1—C7	110.8 (2)
N1—C7—H7	107.5	C9—N1—C7	113.4 (2)
C6—C7—H7	107.5	C1—O1—C10	113.3 (2)
O1—C1—C2—C3	178.7 (3)	C5—C6—C7—N1	164.6 (3)
C6—C1—C2—C3	−1.0 (5)	C1—C6—C7—C8	111.4 (3)
C1—C2—C3—C4	0.3 (5)	C5—C6—C7—C8	−70.8 (4)
C2—C3—C4—C5	0.0 (5)	O1—C10—N1—C9	66.8 (3)
C2—C3—C4—Br1	−178.5 (3)	O1—C10—N1—C7	−63.0 (3)
C3—C4—C5—C6	0.4 (5)	N1^i—C9—N1—C10	163.0 (2)
Br1—C4—C5—C6	178.9 (2)	N1^i—C9—N1—C7	−68.6 (2)
O1—C1—C6—C5	−178.3 (3)	C6—C7—N1—C10	42.8 (3)
C2—C1—C6—C5	1.4 (5)	C8—C7—N1—C10	−83.2 (3)
O1—C1—C6—C7	−0.4 (5)	C6—C7—N1—C9	−87.5 (3)
C2—C1—C6—C7	179.3 (3)	C8—C7—N1—C9	146.5 (3)
C4—C5—C6—C1	−1.0 (5)	C2—C1—O1—C10	164.8 (3)
C4—C5—C6—C7	−179.0 (3)	C6—C1—O1—C10	−15.5 (4)
C1—C6—C7—N1	−13.2 (4)	N1—C10—O1—C1	48.1 (4)

Symmetry code: (i) −x+1, y, −z+1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C7—H7···N1^i	0.98	2.51	2.943 (3)	107
C9—H9B···O1^ii	0.97	2.56	3.418 (4)	147
C9—H9A···O1^iii	0.97	2.56	3.418 (4)	147

Symmetry codes: (i) −x+1, y, −z+1/2; (ii) −x+1, −y+2, −z+1; (iii) x, −y+2, z−1/2.