4-[(4-Bromo­phen­yl)diazen­yl]-2-eth­oxy­aniline

The title compound, C₁₄H₁₄BrN₃O, exhibits a trans geometry about the –N=N– double bond. The dihedral angle between the benzene rings is 24.01 (5)°. An intra­molecular N—H...O hydrogen bond occurs. In the crystal, inter­molecular N—H...N hydrogen bonds between the amine groups lead to the formation of a C(8) polymeric chain along [101].

Key indicators

• Single-crystal X-ray study
• T = 200 K
• Mean [sigma](C-C) = 0.008 Å
• R factor = 0.065
• wR factor = 0.198
• Data-to-parameter ratio = 13.5

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT919_ALERT_3_B Reflection # Likely Affected by the Beamstop ...          1
PLAT934_ALERT_3_B Number of (Iobs-Icalc)/SigmaW .gt. 10 Outliers .          1

Alert level C
PLAT341_ALERT_3_C Low Bond Precision on  C-C Bonds ...............     0.0078 Ang
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.594         24
PLAT918_ALERT_3_C Reflection(s) # with I(obs) much smaller I(calc)          1

Alert level G
PLAT002_ALERT_2_G Number of Distance or Angle Restraints on AtSite          3
PLAT005_ALERT_5_G No _iucr_refine_instructions_details in CIF ....          ?
PLAT072_ALERT_2_G SHELXL First  Parameter in WGHT Unusually Large.       0.14
PLAT128_ALERT_4_G Alternate Setting of Space-group P21/c   .......      P21/n
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          2
PLAT909_ALERT_3_G Percentage of Observed Data at Theta(Max) still          45 Perc.

   0 ALERT level A = Most likely a serious problem - resolve or explain
   2 ALERT level B = A potentially serious problem, consider carefully
   3 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   6 ALERT level G = General information/check it is not something unexpected

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   7 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

We have recenly reported the crystal structure of 4-[(4-chlorophenyl)diazenyl]-3-methoxyaniline (Rofouei et al., 2011), a chloro analogue of the title compound. Diazenyl compounds characterized by having a diazo group (—N═N—) commonly adopt the trans configuration in the ground state. In continuation to our work in this field, we now report the crystal structure of the title compound.

The title molecule (Fig. 1) adopts a trans configuration about the –N1═N2– double bond and the C1—N1—N2—C9 dihedral angle is 177.3 (4)°. The molecular dimensions in the title compound are similar to the corresponding dimensions reported in other azo compounds (Yazici et al., 2006; de Wit et al., 2008; Rofouei et al., 2011).

In the structure of the title compound, the molecules are linked into chain-like polymers along the c axis, with C(8) graph set motif (Bernstein et al., 1995), through N3—H3A···N2ⁱ hydrogen bonds with D···A separation of 3.228 (6) Å (Fig. 2 and Tab. 1). The structure is further consolidated by N3—H3A···O1 intramolecular hydrogen bond with D···A separation of 2.628 (5) Å.

Related literature

For the synthesis and crystal structures of similar diazenyl compounds, see: de Wit et al. (2008); Yazici et al. (2006). For crystal structure of a chloro analogue of the title compound, see: Rofouei et al. (2011). For graph-set motifs, see: Bernstein et al. (1995).

S2. Experimental

To a 100 ml flask in an ice bath, was added (0.349 g, 2 mmol) p-boromoaniline and (3.65 g, 0.1 mol) of HCl (d = 1.18 g.ml^-1). To the obtained solution, was added dropwise a solution of sodium nitrite (0.14 g in 5 ml H₂O). Then, a diluted solution of o-ethoxyaniline (0.244 g, 2 mmol) in methanol (5 ml) was added to the above solution. The pH of the solution was adjusted at about 6–7 by adding a solution of 10% of sodium acetate. The solution was stirred for about an hour, giving an orange precipitate. It was then filtered off and dried in vacuum. After dissolving in diethylether and recrystallization, red crystals of the title compound were obtained. M.p. 373–376 K.

S3. Refinement

Hydrogen atoms bonded to carbon were included at geometrically idealized positions and refined in riding mode with distances H—C = 0.95, 0.98 and 0.99 Å for aryl, methyl and methylene type H-atoms, respectively with U_iso(H) set to 1.2(1.5 for methyl)U_eq(C). Hydrogen atoms bonded to N were located from a difference Fourier map and refined with the N—H distances restrained to 0.88 (1) Å and U_iso(H) = 1.2U_eq(N).

Computing details

Data collection: SMART X2S (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. The molecular structure of the title compound, displacement ellipsoids are drawn at 50% probability level.
	Fig. 2. A part of the unit cell showing N3—H3A···N2 hydrogen bonds, to produce polymeric chain of the title molecules along the c axis.

4-[(4-Bromophenyl)diazenyl]-2-ethoxyaniline

Crystal data

C14H14BrN3O	F(000) = 648
Mr = 320.19	Dx = 1.540 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 2935 reflections
a = 13.219 (2) Å	θ = 2.9–24.8°
b = 8.8289 (17) Å	µ = 2.97 mm^−1
c = 13.506 (2) Å	T = 200 K
β = 118.855 (6)°	Block, yellow
V = 1380.6 (4) Å^3	0.40 × 0.20 × 0.10 mm
Z = 4

Data collection

Bruker SMART X2S benchtop diffractometer	2408 independent reflections
Radiation source: fine-focus sealed tube	1775 reflections with I > 2Σ(I)
Graphite monochromator	Rint = 0.075
Detector resolution: 8.33 pixels mm^-1	θmax = 25.0°, θmin = 1.8°
ω scans	h = −15→13
Absorption correction: multi-scan (SADABS; Bruker, 2009)	k = −10→10
Tmin = 0.383, Tmax = 0.755	l = −16→16
8299 measured reflections

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)] = 0.065	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.198	H atoms treated by a mixture of independent and constrained refinement
S = 1.00	w = 1/[σ^2(Fo^2) + (0.1373P)^2] where P = (Fo^2 + 2Fc^2)/3
2408 reflections	(Δ/σ)max < 0.001
178 parameters	Δρmax = 0.98 e Å^−3
2 restraints	Δρmin = −1.11 e Å^−3

Special details

Experimental. ¹H NMR (300 MHz, d⁶-DMSO): 1.31 (3H, CH₃), 4.10 (2H, OCH₂), 6.72–7.68 (7H, aromatic ring) and 5.87 (2H, NH₂ groups). ¹³C NMR (100 MHz, DMSO): 14.63 (CH₃), 63.44 (OCH₂), 101.60–151.34 (C atoms of aromatic rings).

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
Br1	0.62107 (6)	0.84573 (8)	0.08362 (5)	0.0740 (4)
O1	−0.1368 (3)	0.1305 (4)	−0.0555 (3)	0.0469 (9)
N1	0.1207 (4)	0.4681 (5)	−0.1255 (3)	0.0441 (10)
N2	0.1867 (4)	0.4891 (4)	−0.0227 (3)	0.0444 (10)
N3	−0.2711 (4)	0.1068 (5)	−0.2750 (4)	0.0477 (11)
H3A	−0.296 (5)	0.071 (6)	−0.343 (2)	0.057*
H3B	−0.270 (5)	0.039 (5)	−0.227 (3)	0.057*
C1	0.0220 (4)	0.3782 (5)	−0.1537 (4)	0.0380 (11)
C2	−0.0054 (4)	0.3036 (5)	−0.0774 (4)	0.0396 (11)
H2	0.0424	0.3161	0.0018	0.047*
C3	−0.1012 (4)	0.2134 (5)	−0.1179 (4)	0.0364 (11)
C4	−0.1750 (4)	0.1953 (5)	−0.2364 (4)	0.0368 (11)
C5	−0.1446 (4)	0.2697 (5)	−0.3088 (4)	0.0399 (11)
H5	−0.1917	0.2580	−0.3881	0.048*
C6	−0.0488 (5)	0.3591 (5)	−0.2688 (4)	0.0438 (13)
H6	−0.0305	0.4089	−0.3205	0.053*
C7	−0.0682 (5)	0.1345 (6)	0.0658 (4)	0.0454 (13)
H7A	−0.0598	0.2399	0.0937	0.054*
H7B	0.0096	0.0923	0.0900	0.054*
C8	−0.1313 (5)	0.0403 (7)	0.1108 (4)	0.0601 (15)
H8A	−0.0876	0.0388	0.1936	0.090*
H8B	−0.1396	−0.0633	0.0818	0.090*
H8C	−0.2079	0.0839	0.0864	0.090*
C9	0.2870 (4)	0.5761 (5)	−0.0032 (4)	0.0429 (12)
C10	0.3484 (5)	0.6451 (5)	0.0999 (4)	0.0472 (13)
H10	0.3240	0.6346	0.1552	0.057*
C11	0.4442 (4)	0.7285 (6)	0.1237 (4)	0.0461 (12)
H11	0.4841	0.7798	0.1940	0.055*
C12	0.4832 (4)	0.7385 (6)	0.0462 (4)	0.0479 (13)
C13	0.4241 (6)	0.6680 (7)	−0.0578 (5)	0.0611 (17)
H13	0.4510	0.6746	−0.1115	0.073*
C14	0.3252 (5)	0.5878 (7)	−0.0819 (4)	0.0566 (15)
H14	0.2829	0.5401	−0.1534	0.068*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0634 (5)	0.0968 (6)	0.0643 (5)	−0.0445 (4)	0.0328 (4)	−0.0213 (3)
O1	0.043 (2)	0.060 (2)	0.0371 (17)	−0.0123 (17)	0.0188 (17)	−0.0022 (15)
N1	0.046 (3)	0.043 (2)	0.040 (2)	−0.0016 (19)	0.018 (2)	0.0031 (17)
N2	0.049 (3)	0.043 (2)	0.043 (2)	0.0051 (19)	0.024 (2)	0.0064 (18)
N3	0.045 (3)	0.055 (3)	0.041 (2)	−0.014 (2)	0.019 (2)	−0.0120 (19)
C1	0.034 (3)	0.037 (2)	0.044 (3)	−0.002 (2)	0.020 (2)	−0.0029 (19)
C2	0.031 (3)	0.043 (2)	0.039 (2)	0.000 (2)	0.012 (2)	−0.001 (2)
C3	0.031 (3)	0.038 (2)	0.042 (3)	0.001 (2)	0.019 (2)	−0.002 (2)
C4	0.032 (3)	0.035 (2)	0.043 (3)	0.001 (2)	0.018 (2)	−0.0042 (19)
C5	0.041 (3)	0.043 (3)	0.037 (3)	−0.001 (2)	0.020 (2)	−0.005 (2)
C6	0.055 (3)	0.036 (2)	0.049 (3)	0.000 (2)	0.031 (3)	−0.002 (2)
C7	0.049 (3)	0.049 (3)	0.037 (3)	−0.001 (2)	0.019 (2)	−0.001 (2)
C8	0.068 (4)	0.060 (3)	0.050 (3)	−0.010 (3)	0.028 (3)	0.005 (3)
C9	0.044 (3)	0.043 (3)	0.045 (3)	0.000 (2)	0.023 (2)	0.005 (2)
C10	0.050 (3)	0.049 (3)	0.046 (3)	−0.004 (2)	0.025 (3)	0.002 (2)
C11	0.049 (3)	0.047 (3)	0.036 (3)	−0.004 (2)	0.017 (2)	0.000 (2)
C12	0.040 (3)	0.054 (3)	0.046 (3)	−0.012 (2)	0.018 (2)	0.001 (2)
C13	0.062 (4)	0.081 (4)	0.050 (3)	−0.034 (3)	0.035 (3)	−0.016 (3)
C14	0.050 (3)	0.068 (4)	0.043 (3)	−0.014 (3)	0.015 (3)	−0.010 (3)

Geometric parameters (Å, º)

Br1—C12	1.893 (5)	C6—H6	0.9500
O1—C3	1.361 (6)	C7—C8	1.498 (8)
O1—C7	1.439 (6)	C7—H7A	0.9900
N1—N2	1.246 (5)	C7—H7B	0.9900
N1—C1	1.412 (6)	C8—H8A	0.9800
N2—C9	1.442 (7)	C8—H8B	0.9800
N3—C4	1.363 (7)	C8—H8C	0.9800
N3—H3A	0.876 (10)	C9—C10	1.371 (7)
N3—H3B	0.879 (10)	C9—C14	1.383 (8)
C1—C6	1.384 (7)	C10—C11	1.363 (7)
C1—C2	1.410 (7)	C10—H10	0.9500
C2—C3	1.367 (7)	C11—C12	1.375 (7)
C2—H2	0.9500	C11—H11	0.9500
C3—C4	1.424 (7)	C12—C13	1.383 (7)
C4—C5	1.388 (7)	C13—C14	1.380 (9)
C5—C6	1.363 (7)	C13—H13	0.9500
C5—H5	0.9500	C14—H14	0.9500
C3—O1—C7	118.4 (4)	O1—C7—H7B	110.5
N2—N1—C1	116.3 (4)	C8—C7—H7B	110.5
N1—N2—C9	111.8 (4)	H7A—C7—H7B	108.7
C4—N3—H3A	114 (4)	C7—C8—H8A	109.5
C4—N3—H3B	116 (4)	C7—C8—H8B	109.5
H3A—N3—H3B	113 (5)	H8A—C8—H8B	109.5
C6—C1—C2	119.4 (4)	C7—C8—H8C	109.5
C6—C1—N1	114.1 (4)	H8A—C8—H8C	109.5
C2—C1—N1	126.5 (4)	H8B—C8—H8C	109.5
C3—C2—C1	119.6 (4)	C10—C9—C14	119.4 (5)
C3—C2—H2	120.2	C10—C9—N2	117.6 (5)
C1—C2—H2	120.2	C14—C9—N2	123.0 (5)
O1—C3—C2	126.5 (4)	C11—C10—C9	120.4 (5)
O1—C3—C4	112.5 (4)	C11—C10—H10	119.8
C2—C3—C4	121.0 (4)	C9—C10—H10	119.8
N3—C4—C5	122.3 (4)	C10—C11—C12	120.2 (5)
N3—C4—C3	120.0 (4)	C10—C11—H11	119.9
C5—C4—C3	117.7 (4)	C12—C11—H11	119.9
C6—C5—C4	121.6 (4)	C11—C12—C13	120.6 (5)
C6—C5—H5	119.2	C11—C12—Br1	119.7 (4)
C4—C5—H5	119.2	C13—C12—Br1	119.7 (4)
C5—C6—C1	120.8 (5)	C14—C13—C12	118.4 (5)
C5—C6—H6	119.6	C14—C13—H13	120.8
C1—C6—H6	119.6	C12—C13—H13	120.8
O1—C7—C8	106.3 (4)	C13—C14—C9	120.9 (5)
O1—C7—H7A	110.5	C13—C14—H14	119.6
C8—C7—H7A	110.5	C9—C14—H14	119.6
C1—N1—N2—C9	177.3 (4)	C2—C1—C6—C5	0.2 (7)
N2—N1—C1—C6	179.6 (4)	N1—C1—C6—C5	177.1 (4)
N2—N1—C1—C2	−3.8 (7)	C3—O1—C7—C8	177.1 (5)
C6—C1—C2—C3	0.2 (7)	N1—N2—C9—C10	161.2 (5)
N1—C1—C2—C3	−176.3 (5)	N1—N2—C9—C14	−21.2 (7)
C7—O1—C3—C2	−0.6 (7)	C14—C9—C10—C11	2.1 (8)
C7—O1—C3—C4	178.2 (4)	N2—C9—C10—C11	179.8 (4)
C1—C2—C3—O1	177.6 (5)	C9—C10—C11—C12	−3.0 (8)
C1—C2—C3—C4	−1.0 (7)	C10—C11—C12—C13	1.9 (9)
O1—C3—C4—N3	2.2 (6)	C10—C11—C12—Br1	−176.6 (4)
C2—C3—C4—N3	−178.9 (5)	C11—C12—C13—C14	0.1 (10)
O1—C3—C4—C5	−177.4 (4)	Br1—C12—C13—C14	178.6 (5)
C2—C3—C4—C5	1.5 (7)	C12—C13—C14—C9	−1.0 (10)
N3—C4—C5—C6	179.3 (5)	C10—C9—C14—C13	−0.1 (9)
C3—C4—C5—C6	−1.1 (7)	N2—C9—C14—C13	−177.6 (6)
C4—C5—C6—C1	0.3 (8)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N3—H3A···N2^i	0.88 (1)	2.38 (2)	3.228 (6)	163 (5)
N3—H3B···O1	0.88 (1)	2.28 (5)	2.628 (5)	103 (4)

Symmetry code: (i) x−1/2, −y+1/2, z−1/2.