(E)-2-Methyl-4-(phenyl­diazen­yl)phenol

In the mol­ecule of the title compound, C₁₃H₁₂N₂O, all atoms except for the methyl H atoms are coplanar and the dihedral angle between the aromatic rings is 1.38 (7)°. In the crystal structure, inter­molecular O—H...N and C—H...O hydrogen bonds link the mol­ecules to form two edge-fused R₂²(6) motifs. They are also connected by C—H...π and π–π inter­actions between phenyl­diazenyl rings [centroid-to-centroid distance and plane-to-plane separation 3.708 (1) and 3.418 Å, respectively] to form a three-dimensional network. The two N atoms are disordered over two positions, the site-occupancy ratio being 3:2.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.003 Å
• Disorder in main residue
• R factor = 0.051
• wR factor = 0.152
• Data-to-parameter ratio = 13.0

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT063_ALERT_3_C Crystal Probably too Large for Beam Size .......       0.66 mm
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for        N1B
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for        N2B
PLAT301_ALERT_3_C Main Residue  Disorder .........................      11.00 Perc.
PLAT480_ALERT_4_C Long H...A H-Bond Reported H2     ..  O1      ..       2.65 Ang.

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

   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
   2 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Azo compounds were described over 150 years ago (Stenhouse, 1868; Mohlau, 1883; Witt, 1909; Elion, 1923a,b; Fuch, 1923; Knecht, 1924). They are the oldest and largest class of industrially synthesized organic dyes due to their versatile applications in various fields, such as dyeing textile fibers, biomedical studies, advanced applications in organic synthesis and high technology areas such as lasers, liquid crystalline displays, electro-optical devices and ink-jet printers (Venkataraman, 1970; Egli et al., 1991). There are about 3000 azo dyes currently in use all over the world. The great majority of them are monoazo compounds, which have the common structure unit of the azo chromophore, –N=N–, linking two aromatic systems. The textile industry is the largest consumer of dyestuffs. Although some azo dyes have been reported to be toxic, dozens of additional monoazo dyes are permitted in drugs and cosmetics (Marmion, 1991). The pharmaceutical importance of compounds including an arylazo group has been extensively reported in the literature (Garg & Sharma, 1996; Modest et al., 1957). The oxidation-reduction behaviors of these compounds play an important role in their biological activities (Ravindranath et al., 1983). The structures of some azo derivatives have been the subject of much interest in our laboratory (Odabaşoğlu et al., 2003, 2007; Ersanlı, Albayrak et al., 2004; Ersanlı, Odabaşoğlu et al., 2004; Çakır et al., 2005; Şahin et al., 2005a,b,c,d,e). In view of the importance of the title compound, (I), we report herein its crystal structure.

In the molecule of the title compound, (I), (Fig. 1) the bond lengths and angles are generally within normal ranges (Allen et al., 1987). In the azo group, the N—C and N—N bonds and C—N—N angles are slightly deviate from their normal values (Table 1), due to the disordered N1A and N2A atoms. Aromatic rings adopt a trans configuration about the azo functional group, as observed in the structures of other previously reported azo compounds. Except the methyl protons, all atoms are in the same plane and the dihedral angle between the two aromatic rings is 1.38 (7)°.

In the crystal structure, intermolecular O—H···N and C—H···O hydrogen bonds (Table 2) link the molecules (Fig. 2) to form two edge fused R₂²(6) motifs (Etter, 1990). They are also connected by C—H···π and π···π interactions between (C1–C6) rings at (x, y, z) and (-x, 1 - y, 1 - z), where the centroid-centroid distance and plane-plane separation are 3.708 (1) Å and 3.418 Å, respectively, (Fig. 3) to form a three-dimensional network.

Related literature

For general background, see: Stenhouse (1868); Mohlau (1883); Witt (1909); Elion (1923a,b); Fuch (1923); Knecht (1924); Venkataraman (1970); Egli et al. (1991); Marmion (1991); Garg & Sharma (1996); Modest et al. (1957); Ravindranath et al. (1983); Etter (1990). For related literature, see: Odabaşoğlu et al. (2003, 2007); Ersanlı, Albayrak et al. (2004); Ersanlı, Odabaşoğlu et al. (2004); Çakır et al. (2005); Şahin et al. (2005a,b,c,d,e). For bond-length data, see: Allen et al. (1987).

S2. Experimental

The title compound was prepared according to the literature method (Odabaşoğlu et al., 2003), using aniline and 2-methylphenol as starting materials. The product was crystallized from acetic acid solution to obtain well shaped crystals (yield; 80%, m.p. 408–410 K).

S3. Refinement

When the crystal structure was solved,the atoms N1A and N2A were found to be disordered over two positions. During refinement with anisotropic thermal parameters, the occupancies of disordered N atoms were kept fixed as N1A = 0.63, N1B = 0.37, N2A = 0.63 and N2B = 0.37. H atoms were positioned geometrically with O—H = 0.82 Å (for OH) and C—H = 0.93 and 0.96 Å for aromatic and methyl H atoms, respectively, and constrained to ride on their parent atoms, with U_iso(H) = xU_eq(C,O), where x = 1.2 for aromaic H and x = 1.5 for all other H atoms.

Computing details

Data collection: X-AREA (Stoe & Cie, 2002); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

	Fig. 1. The molecular structure of the title molecule with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.
	Fig. 2. Part of the crystal structure of (I), showing the formation of R2^2(6) R2^2(6) ring motifs. H atoms not involved in intermolecular interactions have been ommited for clarity [symmetry code: (i) x - 1/2, y + 1/2, 1/2 - z].
	Fig. 3. Part of the crystal structure of (I), showing the formation of C—H···π and π···π interactions.H atoms not involved in intermolecular interactions have been ommited for clarity [symmetry code: (i) -x, 1/2 - y, -z; (ii) -x, -y, z; (iii) x - 1, y, z - 1; (iv) x, y - 1, z - 1].

(E)-2-Methyl-4-(phenyldiazenyl)phenol

Crystal data

C13H12N2O	F(000) = 448
Mr = 212.25	Dx = 1.295 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 15802 reflections
a = 9.0537 (6) Å	θ = 1.9–28.0°
b = 10.5716 (9) Å	µ = 0.08 mm^−1
c = 12.0287 (7) Å	T = 296 K
β = 108.952 (4)°	Plate, brown
V = 1088.88 (13) Å^3	0.66 × 0.48 × 0.14 mm
Z = 4

Data collection

Stoe IPDS2 diffractometer	2131 independent reflections
Radiation source: sealed X-ray tube, 12 x 0.4 mm long-fine focus	1457 reflections with I > 2σ(I)
Plane graphite monochromator	Rint = 0.049
Detector resolution: 6.67 pixels mm^-1	θmax = 26.0°, θmin = 2.4°
ω scans	h = −11→11
Absorption correction: integration (X-RED32; Stoe & Cie, 2002)	k = −13→13
Tmin = 0.747, Tmax = 0.949	l = −14→14
15802 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)] = 0.051	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.152	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0899P)^2 + 0.0268P] where P = (Fo^2 + 2Fc^2)/3
2131 reflections	(Δ/σ)max < 0.001
164 parameters	Δρmax = 0.17 e Å^−3
0 restraints	Δρmin = −0.16 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)
O1	0.73324 (15)	−0.02601 (11)	0.37389 (11)	0.0732 (4)
H1	0.7186	−0.0445	0.3049	0.110*
N1A	0.2873 (5)	0.4216 (4)	0.3666 (5)	0.0676 (10)	0.63
N2A	0.3664 (4)	0.3614 (3)	0.4494 (4)	0.0696 (7)	0.63
N1B	0.3083 (6)	0.4176 (4)	0.4572 (5)	0.0504 (11)	0.37
N2B	0.3275 (8)	0.3706 (5)	0.3604 (7)	0.0501 (14)	0.37
C1	0.2013 (2)	0.51896 (18)	0.4215 (3)	0.0841 (7)
C2	0.0993 (2)	0.5789 (2)	0.3269 (2)	0.0864 (6)
H2	0.0932	0.5553	0.2511	0.104*
C3	0.0051 (2)	0.6746 (2)	0.3441 (2)	0.0867 (6)
H3	−0.0647	0.7148	0.2795	0.104*
C4	0.0135 (2)	0.71075 (19)	0.4552 (2)	0.0808 (6)
H4	−0.0501	0.7754	0.4661	0.097*
C5	0.1155 (3)	0.6516 (2)	0.5498 (2)	0.0852 (6)
H5	0.1215	0.6762	0.6253	0.102*
C6	0.2091 (2)	0.5562 (2)	0.5342 (3)	0.0896 (7)
H6	0.2783	0.5162	0.5992	0.108*
C7	0.4448 (3)	0.26581 (18)	0.3974 (3)	0.0822 (7)
C8	0.5429 (3)	0.20592 (19)	0.4970 (2)	0.0795 (6)
H8	0.5426	0.2330	0.5705	0.095*
C9	0.6396 (2)	0.10893 (17)	0.49118 (15)	0.0657 (5)
C10	0.63655 (19)	0.06967 (14)	0.37949 (14)	0.0555 (4)
C11	0.5386 (2)	0.12666 (16)	0.27975 (16)	0.0631 (5)
H11	0.5372	0.0986	0.2061	0.076*
C12	0.4438 (2)	0.22363 (17)	0.2880 (2)	0.0733 (5)
H12	0.3782	0.2616	0.2202	0.088*
C13	0.7481 (3)	0.0461 (2)	0.59793 (18)	0.0968 (8)
H13A	0.8540	0.0581	0.5997	0.145*
H13B	0.7253	−0.0427	0.5955	0.145*
H13C	0.7347	0.0826	0.6671	0.145*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0869 (9)	0.0648 (7)	0.0624 (8)	0.0110 (7)	0.0166 (6)	0.0011 (6)
N1A	0.065 (2)	0.073 (3)	0.063 (3)	−0.0147 (17)	0.0179 (17)	0.005 (2)
N2A	0.0717 (18)	0.074 (2)	0.062 (2)	−0.0149 (15)	0.0205 (17)	0.0044 (16)
N1B	0.055 (2)	0.048 (2)	0.055 (4)	0.0076 (17)	0.027 (2)	−0.002 (2)
N2B	0.060 (3)	0.045 (3)	0.048 (4)	−0.003 (2)	0.021 (2)	0.000 (2)
C1	0.0572 (10)	0.0567 (10)	0.141 (2)	−0.0070 (8)	0.0366 (13)	−0.0023 (12)
C2	0.0700 (12)	0.0943 (15)	0.0991 (17)	−0.0051 (11)	0.0331 (12)	−0.0146 (12)
C3	0.0675 (12)	0.0923 (15)	0.0983 (18)	0.0053 (11)	0.0242 (11)	0.0170 (12)
C4	0.0765 (13)	0.0680 (11)	0.1081 (19)	0.0003 (10)	0.0439 (13)	−0.0014 (11)
C5	0.0815 (13)	0.0839 (13)	0.0917 (16)	−0.0144 (12)	0.0300 (12)	0.0015 (12)
C6	0.0654 (12)	0.0755 (13)	0.118 (2)	−0.0094 (10)	0.0169 (12)	0.0234 (13)
C7	0.0767 (13)	0.0543 (10)	0.136 (2)	−0.0137 (9)	0.0627 (14)	−0.0183 (12)
C8	0.1009 (15)	0.0697 (11)	0.0870 (15)	−0.0335 (11)	0.0571 (13)	−0.0286 (11)
C9	0.0841 (12)	0.0621 (10)	0.0527 (10)	−0.0265 (9)	0.0247 (9)	−0.0069 (8)
C10	0.0651 (9)	0.0490 (8)	0.0531 (10)	−0.0050 (7)	0.0201 (8)	−0.0013 (7)
C11	0.0733 (11)	0.0631 (10)	0.0540 (10)	−0.0020 (8)	0.0220 (8)	0.0033 (7)
C12	0.0668 (11)	0.0610 (10)	0.0928 (15)	0.0018 (8)	0.0268 (10)	0.0148 (9)
C13	0.1265 (19)	0.1026 (16)	0.0507 (12)	−0.0450 (15)	0.0141 (12)	0.0009 (11)

Geometric parameters (Å, º)

C1—C2	1.367 (3)	C7—N2B	1.501 (7)
C1—C6	1.390 (4)	C8—C9	1.365 (3)
C1—N1B	1.418 (6)	C8—H8	0.9300
C1—N1A	1.558 (6)	C9—C10	1.398 (2)
C2—C3	1.381 (3)	C9—C13	1.495 (3)
C2—H2	0.9300	C10—O1	1.3537 (19)
C3—C4	1.368 (3)	C10—C11	1.377 (2)
C3—H3	0.9300	C11—C12	1.362 (3)
C4—C5	1.362 (3)	C11—H11	0.9300
C4—H4	0.9300	C12—H12	0.9300
C5—C6	1.369 (3)	C13—H13A	0.9600
C5—H5	0.9300	C13—H13B	0.9600
C6—H6	0.9300	C13—H13C	0.9600
C7—C12	1.386 (3)	N1A—N2A	1.208 (6)
C7—C8	1.390 (3)	N1B—N2B	1.324 (9)
C7—N2A	1.485 (5)	O1—H1	0.8200
C2—C1—C6	119.1 (2)	C9—C8—H8	118.7
C2—C1—N1B	144.5 (3)	C7—C8—H8	118.7
C6—C1—N1B	96.1 (3)	C8—C9—C10	117.35 (18)
C2—C1—N1A	104.3 (3)	C8—C9—C13	122.9 (2)
C6—C1—N1A	136.5 (3)	C10—C9—C13	119.70 (19)
C1—C2—C3	119.9 (2)	O1—C10—C11	121.83 (16)
C1—C2—H2	120.1	O1—C10—C9	117.30 (16)
C3—C2—H2	120.1	C11—C10—C9	120.87 (17)
C4—C3—C2	120.7 (2)	C12—C11—C10	120.56 (18)
C4—C3—H3	119.7	C12—C11—H11	119.7
C2—C3—H3	119.7	C10—C11—H11	119.7
C5—C4—C3	119.7 (2)	C11—C12—C7	120.1 (2)
C5—C4—H4	120.2	C11—C12—H12	119.9
C3—C4—H4	120.2	C7—C12—H12	119.9
C4—C5—C6	120.4 (2)	C9—C13—H13A	109.5
C4—C5—H5	119.8	C9—C13—H13B	109.5
C6—C5—H5	119.8	H13A—C13—H13B	109.5
C5—C6—C1	120.3 (2)	C9—C13—H13C	109.5
C5—C6—H6	119.9	H13A—C13—H13C	109.5
C1—C6—H6	119.9	H13B—C13—H13C	109.5
C12—C7—C8	118.45 (18)	N2A—N1A—C1	104.3 (6)
C12—C7—N2A	139.7 (3)	N1A—N2A—C7	104.6 (6)
C8—C7—N2A	101.8 (2)	N2B—N1B—C1	106.6 (7)
C12—C7—N2B	99.9 (3)	N1B—N2B—C7	107.2 (7)
C8—C7—N2B	141.7 (3)	C10—O1—H1	109.5
C9—C8—C7	122.63 (19)
C6—C1—C2—C3	−0.4 (3)	C9—C10—C11—C12	0.7 (3)
N1B—C1—C2—C3	173.1 (3)	C10—C11—C12—C7	−0.1 (3)
N1A—C1—C2—C3	−178.5 (2)	C8—C7—C12—C11	−0.7 (3)
C1—C2—C3—C4	0.4 (3)	N2A—C7—C12—C11	−179.1 (2)
C2—C3—C4—C5	−0.1 (3)	N2B—C7—C12—C11	179.1 (3)
C3—C4—C5—C6	−0.1 (3)	C2—C1—N1A—N2A	−173.9 (3)
C4—C5—C6—C1	0.1 (3)	C6—C1—N1A—N2A	8.5 (4)
C2—C1—C6—C5	0.1 (3)	N1B—C1—N1A—N2A	−1.3 (3)
N1B—C1—C6—C5	−176.1 (2)	C1—N1A—N2A—C7	178.2 (2)
N1A—C1—C6—C5	177.5 (3)	C12—C7—N2A—N1A	−5.9 (4)
C12—C7—C8—C9	1.0 (3)	C8—C7—N2A—N1A	175.6 (2)
N2A—C7—C8—C9	179.94 (18)	N2B—C7—N2A—N1A	−3.0 (5)
N2B—C7—C8—C9	−178.6 (4)	C2—C1—N1B—N2B	9.6 (6)
C7—C8—C9—C10	−0.5 (3)	C6—C1—N1B—N2B	−176.1 (3)
C7—C8—C9—C13	178.53 (17)	N1A—C1—N1B—N2B	−2.9 (4)
C8—C9—C10—O1	179.59 (14)	C1—N1B—N2B—C7	178.2 (3)
C13—C9—C10—O1	0.6 (2)	C12—C7—N2B—N1B	176.7 (4)
C8—C9—C10—C11	−0.4 (2)	C8—C7—N2B—N1B	−3.6 (7)
C13—C9—C10—C11	−179.46 (16)	N2A—C7—N2B—N1B	−1.4 (3)
O1—C10—C11—C12	−179.29 (15)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···N2B^i	0.82	2.10	2.904 (8)	168
O1—H1···N1A^i	0.82	2.08	2.891 (6)	172
C2—H2···O1^ii	0.93	2.65	3.427 (3)	142
C12—H12···O1^ii	0.93	2.57	3.367 (2)	144

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