2-Acetyl-4-(4-ethoxy­phenyl­diazen­yl)phenol

In the title structure, C₁₆H₁₆N₂O₃, the benzene rings are in a trans configuration with respect to the azo double bond and the mol­ecule is essentially planar.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.053
• wR factor = 0.173
• Data-to-parameter ratio = 15.1

checkCIF/PLATON results

No syntax errors found



Alert level C
RINTA01_ALERT_3_C  The value of Rint is greater than 0.10
            Rint given   0.111
PLAT020_ALERT_3_C The value of Rint is greater than 0.10 .........       0.11
PLAT026_ALERT_3_C Ratio Observed / Unique Reflections too Low ....         42 Perc.
PLAT063_ALERT_3_C Crystal Probably too Large for Beam Size .......       0.80 mm
PLAT380_ALERT_4_C Check Incorrectly? Oriented X(sp2)-Methyl Moiety        C14

   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
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   4 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion

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S1. Comment

Azo compounds have been the most widely used class of dyes owing to their versatile application in various fields, such as dyeing textile fibres, colouring different materials, plastics, biological medical studies, lasers, liquid crystalline displays, electrooptical devices and ink-jet printers in high-technology areas (Catino & Farris, 1985; Gregory, 1991). In azo compounds, conversion from the trans to the cis form can lead to photochromism. Photochromic compounds are of great interest for the control and measurement of radiation intensity, optical computers and display systems (Dürr & Bouas-Laurent, 1990), and for potential applications in molecular electronic devices (Martin et al., 1995). As part of a general study of the crystal chemistry of dyes, and to provide templates for molecular-modelling studies, the crystal structure of the title compound, (I), has been determined.

The molecular structure of (I) is shown in Fig. 1 and selected geometric parameters are given in Table 1. The bond lengths and angles of the azo group are as expected. The molecules is essentially planar, with dihedral angles between the mean planes of the benzene rings and the C1—N1═N2—C7 azo bridge of 6.19 (6) and 4.12 (4) Å for rings C1–C6 and C7–C12, respectively. The angle between the planes of the two benzene rings is 10.14 (4) Å. Apart from the expected intramolecular O—H···O hydrogen bond (Table 2) there are no other significant hydrogen-bond interactions, the closest contacts being of the types C—H···O and C—H···π, with distances ca 2.7 Å for H···O and H···π(ring centroid).

S2. Experimental

The compound was prepared by using 4-ethoxyaniline and 2-hydroxyacetophenone as for Deveci et al. (2005). Crystals of 2-acetyl-4-(4-ethoxyphenyldiazenyl)phenol were obtained after 1 d by slow evaporation of an acetonitrile solution (yield 56%, m.p. 408–410 K).

S3. Refinement

All H atoms were positioned geometrically and refined using a riding model, with C—H = 0.93–0.97 Å and O—H = 0.82 Å. U_iso(H) values were set at 1.2U_eq(C) or 1.5U_eq(O or C_methyl).

Computing details

Data collection: X-AREA (Stoe & Cie, 2002); cell refinement: X-AREA; data reduction: X-RED (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. A view of (I), showing the atom-numbering scheme and 50% probability displacement ellipsoids. A dashed line indicates an intramolecular hydrogen bond

2-Acetyl-4-(4-ethoxyphenyldiazenyl)phenol

Crystal data

C16H16N2O3	F(000) = 1200
Mr = 284.31	Dx = 1.296 Mg m^−3
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 13929 reflections
a = 7.2099 (5) Å	θ = 2.8–27.9°
b = 13.6448 (9) Å	µ = 0.09 mm^−1
c = 29.631 (3) Å	T = 296 K
V = 2915.0 (4) Å^3	Plate, brown
Z = 8	0.80 × 0.39 × 0.06 mm

Data collection

Stoe IPDS-2 diffractometer	2864 independent reflections
Radiation source: fine-focus sealed tube	1211 reflections with I > 2σ(I)
Plane graphite monochromator	Rint = 0.111
Detector resolution: 6.67 pixels mm^-1	θmax = 26.0°, θmin = 2.8°
ω scans	h = −8→8
Absorption correction: integration (X-RED32; Stoe & Cie, 2002)	k = −16→16
Tmin = 0.951, Tmax = 0.994	l = −36→36
19031 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)] = 0.053	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.173	H-atom parameters constrained
S = 0.89	w = 1/[σ^2(Fo^2) + (0.0811P)^2] where P = (Fo^2 + 2Fc^2)/3
2864 reflections	(Δ/σ)max < 0.001
190 parameters	Δρmax = 0.12 e Å^−3
0 restraints	Δρmin = −0.20 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
C1	0.8272 (4)	−0.0347 (2)	0.59115 (10)	0.0524 (8)
C2	0.8452 (5)	−0.1316 (2)	0.60473 (10)	0.0577 (8)
H2	0.8596	−0.1465	0.6352	0.069*
C3	0.8417 (5)	−0.2051 (2)	0.57334 (10)	0.0600 (8)
H3	0.8535	−0.2699	0.5826	0.072*
C4	0.8206 (4)	−0.1839 (2)	0.52728 (10)	0.0555 (8)
C5	0.8014 (5)	−0.0876 (2)	0.51366 (10)	0.0622 (9)
H5	0.7854	−0.0725	0.4833	0.075*
C6	0.8061 (4)	−0.0137 (2)	0.54582 (11)	0.0602 (9)
H6	0.7949	0.0512	0.5367	0.072*
C7	0.8510 (4)	0.1033 (2)	0.69271 (10)	0.0547 (8)
C8	0.8666 (5)	0.2011 (2)	0.67913 (12)	0.0650 (9)
H8	0.8730	0.2168	0.6486	0.078*
C9	0.8724 (5)	0.2737 (2)	0.71116 (12)	0.0709 (10)
H9	0.8807	0.3389	0.7022	0.085*
C10	0.8660 (5)	0.2509 (2)	0.75649 (12)	0.0641 (9)
C11	0.8538 (5)	0.1538 (2)	0.77104 (10)	0.0566 (8)
C12	0.8463 (5)	0.0806 (2)	0.73799 (10)	0.0552 (8)
H12	0.8380	0.0153	0.7468	0.066*
C13	0.8508 (5)	0.1304 (3)	0.81956 (12)	0.0659 (9)
C14	0.8396 (6)	0.0269 (3)	0.83615 (11)	0.0765 (11)
H14A	0.8393	0.0265	0.8685	0.115*
H14B	0.9448	−0.0094	0.8253	0.115*
H14C	0.7277	−0.0029	0.8252	0.115*
C15	0.8229 (5)	−0.2471 (2)	0.45200 (11)	0.0672 (9)
H15A	0.9296	−0.2081	0.4433	0.081*
H15B	0.7113	−0.2126	0.4429	0.081*
C16	0.8310 (5)	−0.3467 (2)	0.42971 (12)	0.0752 (10)
H16A	0.8313	−0.3389	0.3975	0.113*
H16B	0.7248	−0.3846	0.4386	0.113*
H16C	0.9420	−0.3800	0.4389	0.113*
N1	0.8336 (4)	0.04659 (17)	0.62121 (8)	0.0566 (7)
N2	0.8395 (4)	0.02273 (18)	0.66180 (8)	0.0571 (7)
O1	0.8716 (4)	0.32704 (17)	0.78556 (9)	0.0918 (9)
H1	0.8674	0.3064	0.8115	0.138*
O2	0.8579 (4)	0.1976 (2)	0.84779 (8)	0.0922 (9)
O3	0.8226 (4)	−0.26316 (15)	0.49955 (7)	0.0669 (7)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.061 (2)	0.0463 (16)	0.0501 (18)	−0.0014 (15)	0.0047 (15)	−0.0036 (13)
C2	0.070 (2)	0.0555 (18)	0.0473 (17)	0.0024 (17)	0.0020 (16)	0.0023 (15)
C3	0.077 (2)	0.0472 (16)	0.0562 (19)	0.0018 (16)	0.0025 (17)	0.0006 (15)
C4	0.061 (2)	0.0509 (16)	0.0544 (18)	−0.0035 (16)	0.0033 (16)	−0.0078 (15)
C5	0.084 (3)	0.056 (2)	0.0470 (17)	−0.0047 (18)	0.0004 (17)	0.0002 (15)
C6	0.077 (2)	0.0474 (17)	0.0566 (19)	−0.0048 (16)	0.0048 (16)	0.0035 (15)
C7	0.0570 (19)	0.0488 (17)	0.0584 (19)	0.0000 (16)	−0.0031 (16)	−0.0074 (15)
C8	0.079 (3)	0.0532 (18)	0.063 (2)	−0.0004 (17)	−0.0065 (18)	0.0007 (16)
C9	0.092 (3)	0.0392 (16)	0.082 (3)	−0.0043 (18)	−0.009 (2)	−0.0015 (17)
C10	0.074 (2)	0.0523 (18)	0.066 (2)	0.0022 (18)	−0.0095 (18)	−0.0158 (17)
C11	0.061 (2)	0.0546 (17)	0.0545 (18)	0.0035 (16)	−0.0070 (16)	−0.0129 (14)
C12	0.062 (2)	0.0496 (16)	0.0536 (19)	0.0020 (16)	−0.0031 (15)	−0.0031 (14)
C13	0.064 (2)	0.070 (2)	0.064 (2)	0.0036 (18)	−0.0098 (17)	−0.0177 (18)
C14	0.092 (3)	0.076 (2)	0.061 (2)	0.004 (2)	−0.002 (2)	−0.0026 (18)
C15	0.082 (3)	0.066 (2)	0.0532 (19)	−0.0043 (19)	0.0007 (18)	−0.0079 (16)
C16	0.086 (3)	0.070 (2)	0.070 (2)	0.004 (2)	−0.009 (2)	−0.0185 (18)
N1	0.0703 (18)	0.0530 (14)	0.0465 (15)	−0.0014 (13)	−0.0006 (14)	−0.0005 (12)
N2	0.0680 (18)	0.0501 (14)	0.0532 (16)	0.0002 (13)	0.0000 (13)	−0.0046 (12)
O1	0.124 (2)	0.0582 (14)	0.0935 (19)	0.0027 (16)	−0.0151 (17)	−0.0299 (14)
O2	0.127 (2)	0.0839 (17)	0.0655 (16)	−0.0004 (17)	−0.0070 (16)	−0.0253 (14)
O3	0.0962 (18)	0.0553 (13)	0.0492 (12)	−0.0015 (13)	0.0008 (12)	−0.0071 (10)

Geometric parameters (Å, º)

C1—C6	1.382 (4)	C10—O1	1.350 (4)
C1—C2	1.389 (4)	C10—C11	1.397 (4)
C1—N1	1.423 (4)	C11—C12	1.399 (4)
C2—C3	1.368 (4)	C11—C13	1.473 (4)
C2—H2	0.9300	C12—H12	0.9300
C3—C4	1.403 (4)	C13—O2	1.242 (4)
C3—H3	0.9300	C13—C14	1.497 (5)
C4—O3	1.359 (3)	C14—H14A	0.9600
C4—C5	1.381 (4)	C14—H14B	0.9600
C5—C6	1.387 (4)	C14—H14C	0.9600
C5—H5	0.9300	C15—O3	1.426 (4)
C6—H6	0.9300	C15—C16	1.513 (4)
C7—C12	1.377 (4)	C15—H15A	0.9700
C7—C8	1.398 (4)	C15—H15B	0.9700
C7—N2	1.433 (4)	C16—H16A	0.9600
C8—C9	1.373 (4)	C16—H16B	0.9600
C8—H8	0.9300	C16—H16C	0.9600
C9—C10	1.379 (5)	N1—N2	1.247 (3)
C9—H9	0.9300	O1—H1	0.8200
C6—C1—C2	119.3 (3)	C10—C11—C13	120.5 (3)
C6—C1—N1	116.8 (3)	C12—C11—C13	121.9 (3)
C2—C1—N1	123.9 (3)	C7—C12—C11	121.4 (3)
C3—C2—C1	120.0 (3)	C7—C12—H12	119.3
C3—C2—H2	120.0	C11—C12—H12	119.3
C1—C2—H2	120.0	O2—C13—C11	119.8 (3)
C2—C3—C4	120.8 (3)	O2—C13—C14	118.5 (3)
C2—C3—H3	119.6	C11—C13—C14	121.7 (3)
C4—C3—H3	119.6	C13—C14—H14A	109.5
O3—C4—C5	125.6 (3)	C13—C14—H14B	109.5
O3—C4—C3	115.0 (3)	H14A—C14—H14B	109.5
C5—C4—C3	119.4 (3)	C13—C14—H14C	109.5
C4—C5—C6	119.2 (3)	H14A—C14—H14C	109.5
C4—C5—H5	120.4	H14B—C14—H14C	109.5
C6—C5—H5	120.4	O3—C15—C16	107.1 (3)
C1—C6—C5	121.4 (3)	O3—C15—H15A	110.3
C1—C6—H6	119.3	C16—C15—H15A	110.3
C5—C6—H6	119.3	O3—C15—H15B	110.3
C12—C7—C8	119.8 (3)	C16—C15—H15B	110.3
C12—C7—N2	116.7 (3)	H15A—C15—H15B	108.6
C8—C7—N2	123.6 (3)	C15—C16—H16A	109.5
C9—C8—C7	119.5 (3)	C15—C16—H16B	109.5
C9—C8—H8	120.2	H16A—C16—H16B	109.5
C7—C8—H8	120.2	C15—C16—H16C	109.5
C8—C9—C10	120.6 (3)	H16A—C16—H16C	109.5
C8—C9—H9	119.7	H16B—C16—H16C	109.5
C10—C9—H9	119.7	N2—N1—C1	113.7 (2)
O1—C10—C9	116.6 (3)	N1—N2—C7	114.7 (2)
O1—C10—C11	122.3 (3)	C10—O1—H1	109.5
C9—C10—C11	121.1 (3)	C4—O3—C15	118.4 (2)
C10—C11—C12	117.6 (3)
C6—C1—C2—C3	−0.1 (5)	C9—C10—C11—C13	178.8 (3)
N1—C1—C2—C3	−178.5 (3)	C8—C7—C12—C11	1.1 (5)
C1—C2—C3—C4	0.2 (5)	N2—C7—C12—C11	−179.0 (3)
C2—C3—C4—O3	178.9 (3)	C10—C11—C12—C7	0.1 (5)
C2—C3—C4—C5	−0.6 (5)	C13—C11—C12—C7	−179.4 (3)
O3—C4—C5—C6	−178.5 (3)	C10—C11—C13—O2	0.5 (5)
C3—C4—C5—C6	1.0 (5)	C12—C11—C13—O2	179.9 (3)
C2—C1—C6—C5	0.4 (5)	C10—C11—C13—C14	−179.4 (3)
N1—C1—C6—C5	178.9 (3)	C12—C11—C13—C14	0.0 (5)
C4—C5—C6—C1	−0.9 (5)	C6—C1—N1—N2	175.2 (3)
C12—C7—C8—C9	−1.6 (5)	C2—C1—N1—N2	−6.4 (5)
N2—C7—C8—C9	178.5 (3)	C1—N1—N2—C7	178.4 (3)
C7—C8—C9—C10	1.1 (5)	C12—C7—N2—N1	176.1 (3)
C8—C9—C10—O1	−179.7 (3)	C8—C7—N2—N1	−4.0 (4)
C8—C9—C10—C11	0.1 (6)	C5—C4—O3—C15	6.4 (5)
O1—C10—C11—C12	179.1 (3)	C3—C4—O3—C15	−173.1 (3)
C9—C10—C11—C12	−0.7 (5)	C16—C15—O3—C4	178.4 (3)
O1—C10—C11—C13	−1.4 (5)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O2	0.82	1.83	2.555 (4)	146
C14—H14C···O1^i	0.96	2.70	3.464 (4)	137
C16—H16C···G1^ii	0.96	2.75	3.617 (4)	149

Symmetry codes: (i) −x+3/2, y−1/2, z; (ii) x−1/2, −y+1/2, −z.