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Acta Crystallogr Sect E Struct Rep Online. 2009 November 1; 65(Pt 11): o2705.
Published online 2009 October 10. doi:  10.1107/S1600536809040586
PMCID: PMC2971308

(E)-2-[(4-Ethoxy­phen­yl)imino­meth­yl]-4-methoxy­phenol

Abstract

In the mol­ecule of the title compound, C16H17NO3, the aromatic rings are oriented at a dihedral angle of 29.25 (8)°. An intra­molecular O—H(...)N hydrogen bond results in the formation of a nearly planar [maximum deviation 0.034 (13) Å] six-membered ring, which is oriented at dihedral angles of 0.91 (1) and 28.91 (12)° with respect to the aromatic rings. The title mol­ecule is a phenol–imine tautomer, as evidenced by C—O, C—N and C—C bond lengths. In the crystal, mol­ecules are linked by inter­molecular C—H(...)O hydrogen bonds that generate C(8) chains.

Related literature

For background to this study, see: Özek et al., 2007 [triangle]. For related structures, see: Özek et al. (2009 [triangle]); Özek et al. (2008 [triangle]).

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Object name is e-65-o2705-scheme1.jpg

Experimental

Crystal data

  • C16H17NO3
  • M r = 271.31
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-65-o2705-efi1.jpg
  • a = 14.8558 (7) Å
  • b = 13.7669 (7) Å
  • c = 6.9042 (3) Å
  • β = 90.287 (4)°
  • V = 1412.02 (11) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.09 mm−1
  • T = 296 K
  • 0.77 × 0.51 × 0.28 mm

Data collection

  • Stoe IPDS II diffractometer
  • Absorption correction: integration (X-RED32; Stoe & Cie, 2002 [triangle]) T min = 0.943, T max = 0.973
  • 14704 measured reflections
  • 2938 independent reflections
  • 2014 reflections with I > 2σ(I)
  • R int = 0.051

Refinement

  • R[F 2 > 2σ(F 2)] = 0.044
  • wR(F 2) = 0.123
  • S = 1.04
  • 2938 reflections
  • 250 parameters
  • All H-atom parameters refined
  • Δρmax = 0.11 e Å−3
  • Δρmin = −0.12 e Å−3

Data collection: X-AREA (Stoe & Cie, 2002 [triangle]); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2002 [triangle]); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 [triangle]); software used to prepare material for publication: WinGX (Farrugia, 1999 [triangle]).

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809040586/ez2189sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809040586/ez2189Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

The authors acknowledge the Faculty of Arts and Sciences, Ondokuz Mayıs University, Turkey, for the use of the Stoe IPDS II diffractometer (purchased under grant F.279 of the University Research Fund).

supplementary crystallographic information

Comment

The present work is part of a structural study of Schiff bases (Özek et al., 2009; Özek et al., 2008; Özek et al., 2007) and we report here the structure of (E)-2-[(4-ethoxyphenylimino)methyl]-4-methoxyphenol, (I).

In general, O-hydroxy Schiff bases exhibit two possible tautomeric forms, the phenol-imine (or benzenoid) and keto-amine (or quinoid) forms. Depending on the tautomers, two types of intra-molecular hydrogen bonds are possible: O—H···N in benzenoid and N—H···O in quinoid tautomers. In the title compound the H atom is located on atom O1, thus the phenol-imine tautomer is favored over the keto-amine form, as indicated by the C2—O1, C8—N1, C1—C8 and C1—C2 bond lengths (Fig. 1 and Table 2). The O1—C2 bond length of 1.351 (2) Å indicates single-bond character, whereas the N1—C8 bond length of 1.277 (2) Å indicates a high degree of double-bond character. A similar result was observed in the X-ray crystal and computational structural study of (E)-2-[(2-chlorophenyl) iminomethyl]-4-methoxyphenol [C—O=1.357 (17) Å, C—N= 1.278 (17) Å, Özek et al., 2008.

It is known that Schiff bases may exhibit thermochromism or photochromism, depending on the planarity or non-planarity of the molecule, respectively. Therefore, one can expect photochromic properties in (I) caused by non-planarity of the molecules; the dihedral angle between ring A (C1—C6) and ring B (C9—C14) is 29.25 (8) °. The intramolecular O—H···N hydrogen bond (Table 1) results in the formation of a nearly planar six-membered ring C (O1/H1/N1/C1/C2/C8), in which it is oriented with respect to rings A and B at dihedral angles of A/C= 0.91 (1) ° and B/C= 28.91 (12) °. It is thus coplanar with the adjacent ring A. It generates an S(6) ring motif. The O1···N1 distance of 2.5962 (18) Å is comparable to those observed for analogous hydrogen bonds in three (E)-2-[(bromophenyl)iminomethyl]-4-methoxyphenols [2.603 (2) Å, 2.638 (7) Å, 2.577 (4) Å; Özek et al., 2007]. In the crystal structure, weak intermolecular C—H···O hydrogen bonds (Table 1) result in the formation of C(8) chains along the c axis (Fig. 2), which may play a role in the stabilization of the structure.

Experimental

The compound (E)-2-[(4-ethoxyphenylimino)methyl]-4-methoxyphenol was prepared by refluxing a mixture of a solution containing 5-methoxysalicylaldehyde (0.5 g, 3.3 mmol) in 20 ml ethanol and a solution containing 4-ethoxyaniline (0.45 g, 3.3 mmol) in 20 ml ethanol. The reaction mixture was stirred for 1 h under reflux. Crystals of (E)-2-[(4-ethoxyphenylimino)methyl]-4- methoxyphenol suitable for X-ray analysis were obtained from ethanol by slow evaporation (yield % 75; m.p. 365–367 K).

Refinement

All the H-atoms were found in difference-density maps, and refined freely. The C—H bond lengths are 0.90 (3)–1.06 (2) Å.

Figures

Fig. 1.
A view of (I), with the atom-numbering scheme and 30% probability displacement ellipsoids. The dashed line indicates the intramolecular hydrogen bond.
Fig. 2.
A partial packing view of (I), showing the formation of the C(8) chain through C—H···O hydrogen bonds (dashed lines). H atoms are represented as small spheres of arbitrary radii and H atoms not involved in hydrogen bonding ...

Crystal data

C16H17NO3F(000) = 576
Mr = 271.31Dx = 1.276 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 14704 reflections
a = 14.8558 (7) Åθ = 2.0–28.0°
b = 13.7669 (7) ŵ = 0.09 mm1
c = 6.9042 (3) ÅT = 296 K
β = 90.287 (4)°Prism, brown
V = 1412.02 (11) Å30.77 × 0.51 × 0.28 mm
Z = 4

Data collection

Stoe IPDS II diffractometer2938 independent reflections
Radiation source: fine-focus sealed tube2014 reflections with I > 2σ(I)
plane graphiteRint = 0.051
Detector resolution: 6.67 pixels mm-1θmax = 26.5°, θmin = 2.0°
ω scansh = −18→18
Absorption correction: integration (X-RED32; Stoe & Cie, 2002)k = −17→17
Tmin = 0.943, Tmax = 0.973l = −8→7
14704 measured reflections

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.044All H-atom parameters refined
wR(F2) = 0.123w = 1/[σ2(Fo2) + (0.0671P)2] where P = (Fo2 + 2Fc2)/3
S = 1.04(Δ/σ)max < 0.001
2938 reflectionsΔρmax = 0.11 e Å3
250 parametersΔρmin = −0.12 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0043 (13)

Special details

Experimental. 260 frames, detector distance = 100 mm
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 (Å2)

xyzUiso*/Ueq
C10.67303 (10)0.38075 (10)0.1954 (2)0.0592 (4)
C20.66776 (11)0.36315 (11)−0.0041 (2)0.0644 (4)
C30.74627 (12)0.35280 (13)−0.1091 (2)0.0738 (5)
C40.82841 (13)0.35935 (13)−0.0201 (2)0.0743 (5)
C50.83522 (11)0.37538 (12)0.1785 (2)0.0677 (4)
C60.75803 (10)0.38680 (12)0.2840 (2)0.0633 (4)
C70.93120 (15)0.38888 (19)0.4548 (3)0.0868 (6)
C80.59256 (11)0.38970 (11)0.3128 (2)0.0635 (4)
C90.43564 (10)0.38370 (11)0.3529 (2)0.0587 (4)
C100.43263 (11)0.35185 (12)0.5428 (2)0.0663 (4)
C110.35242 (11)0.34958 (13)0.6444 (2)0.0669 (4)
C120.27310 (10)0.37865 (10)0.5544 (2)0.0593 (4)
C130.27591 (11)0.41068 (12)0.3634 (2)0.0658 (4)
C140.35554 (10)0.41219 (12)0.2639 (2)0.0647 (4)
C150.18545 (13)0.35600 (18)0.8412 (3)0.0808 (5)
C160.08889 (15)0.3588 (2)0.8994 (4)0.1001 (7)
N10.51409 (8)0.38318 (9)0.23737 (18)0.0634 (3)
O10.58802 (9)0.35510 (10)−0.09793 (18)0.0830 (4)
O20.92111 (8)0.37741 (11)0.25288 (18)0.0904 (4)
O30.19015 (7)0.37712 (8)0.63865 (15)0.0709 (3)
H10.5439 (17)0.3668 (16)−0.006 (3)0.116 (8)*
H30.7423 (13)0.3381 (14)−0.243 (3)0.100 (6)*
H40.8816 (14)0.3471 (14)−0.091 (3)0.093 (6)*
H60.7613 (11)0.3976 (13)0.421 (3)0.083 (5)*
H7A0.9038 (14)0.4477 (18)0.503 (3)0.105 (7)*
H7B0.8999 (13)0.3335 (15)0.528 (3)0.093 (6)*
H7C0.9976 (15)0.3864 (13)0.473 (3)0.096 (6)*
H80.6036 (11)0.4006 (12)0.449 (3)0.080 (5)*
H100.4858 (12)0.3266 (13)0.606 (2)0.082 (5)*
H110.3521 (11)0.3218 (13)0.777 (3)0.084 (5)*
H130.2221 (11)0.4322 (12)0.307 (2)0.073 (5)*
H140.3585 (10)0.4324 (13)0.130 (2)0.077 (5)*
H15A0.2218 (13)0.4035 (14)0.913 (3)0.090 (6)*
H15B0.2105 (13)0.2887 (16)0.862 (3)0.112 (7)*
H16A0.0524 (19)0.304 (2)0.825 (4)0.158 (11)*
H16B0.0618 (16)0.4162 (19)0.873 (4)0.128 (9)*
H16C0.0829 (14)0.3476 (15)1.038 (4)0.105 (7)*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
C10.0603 (8)0.0579 (8)0.0594 (8)0.0004 (6)0.0039 (6)−0.0015 (6)
C20.0680 (9)0.0663 (10)0.0589 (8)−0.0002 (7)−0.0019 (7)0.0026 (7)
C30.0824 (12)0.0850 (12)0.0542 (9)0.0049 (8)0.0085 (8)0.0022 (8)
C40.0714 (11)0.0849 (12)0.0666 (10)0.0082 (8)0.0157 (8)0.0059 (8)
C50.0598 (9)0.0752 (10)0.0682 (9)0.0016 (7)0.0055 (7)0.0066 (7)
C60.0619 (9)0.0718 (10)0.0561 (8)−0.0011 (7)0.0043 (7)−0.0025 (7)
C70.0665 (12)0.1075 (17)0.0864 (13)−0.0070 (11)−0.0097 (9)−0.0061 (12)
C80.0634 (9)0.0665 (10)0.0605 (9)0.0000 (7)0.0005 (7)−0.0065 (7)
C90.0577 (8)0.0580 (8)0.0604 (8)0.0005 (6)−0.0006 (6)−0.0042 (6)
C100.0574 (8)0.0769 (10)0.0645 (9)0.0066 (7)−0.0065 (7)0.0038 (7)
C110.0627 (9)0.0768 (10)0.0610 (9)0.0051 (7)−0.0026 (7)0.0078 (8)
C120.0546 (8)0.0601 (9)0.0633 (8)0.0009 (6)0.0002 (6)−0.0028 (7)
C130.0580 (9)0.0769 (10)0.0625 (9)0.0070 (7)−0.0078 (7)0.0016 (7)
C140.0651 (9)0.0737 (10)0.0554 (8)0.0031 (7)−0.0026 (7)0.0020 (7)
C150.0702 (11)0.1014 (15)0.0707 (11)0.0031 (10)0.0062 (8)0.0190 (10)
C160.0712 (13)0.139 (2)0.0902 (15)0.0020 (13)0.0187 (11)0.0247 (15)
N10.0595 (8)0.0655 (8)0.0651 (7)−0.0001 (6)0.0016 (6)−0.0029 (6)
O10.0742 (8)0.1130 (10)0.0616 (7)−0.0007 (6)−0.0088 (6)−0.0047 (6)
O20.0576 (7)0.1344 (12)0.0794 (8)0.0014 (6)0.0047 (6)0.0062 (7)
O30.0564 (6)0.0901 (8)0.0661 (6)0.0021 (5)0.0011 (5)0.0055 (5)

Geometric parameters (Å, °)

C1—C21.401 (2)C9—C141.393 (2)
C1—C61.403 (2)C9—N11.4154 (19)
C1—C81.453 (2)C10—C111.386 (2)
C2—O11.3518 (19)C10—H100.965 (18)
C2—C31.384 (2)C11—C121.388 (2)
C3—C41.367 (3)C11—H110.990 (17)
C3—H30.94 (2)C12—O31.3653 (18)
C4—C51.392 (2)C12—C131.392 (2)
C4—H40.95 (2)C13—C141.371 (2)
C5—C61.371 (2)C13—H130.936 (17)
C5—O21.373 (2)C14—H140.966 (17)
C6—H60.957 (18)C15—O31.431 (2)
C7—O21.410 (2)C15—C161.492 (3)
C7—H7A0.97 (2)C15—H15A0.98 (2)
C7—H7B1.03 (2)C15—H15B1.01 (2)
C7—H7C0.99 (2)C16—H16A1.06 (3)
C8—N11.277 (2)C16—H16B0.90 (3)
C8—H80.963 (18)C16—H16C0.98 (2)
C9—C101.384 (2)O1—H10.93 (3)
C2—C1—C6119.01 (14)C9—C10—H10120.8 (10)
C2—C1—C8121.41 (14)C11—C10—H10117.9 (10)
C6—C1—C8119.55 (13)C10—C11—C12119.84 (15)
O1—C2—C3118.65 (14)C10—C11—H11118.9 (10)
O1—C2—C1122.00 (14)C12—C11—H11121.1 (10)
C3—C2—C1119.35 (15)O3—C12—C11124.83 (14)
C4—C3—C2120.70 (16)O3—C12—C13116.10 (13)
C4—C3—H3120.3 (12)C11—C12—C13119.06 (14)
C2—C3—H3119.0 (12)C14—C13—C12120.63 (15)
C3—C4—C5120.92 (16)C14—C13—H13121.6 (10)
C3—C4—H4120.2 (12)C12—C13—H13117.7 (10)
C5—C4—H4118.7 (12)C13—C14—C9120.83 (15)
C6—C5—O2125.23 (15)C13—C14—H14121.8 (9)
C6—C5—C4119.02 (16)C9—C14—H14117.4 (9)
O2—C5—C4115.75 (14)O3—C15—C16108.04 (16)
C5—C6—C1120.99 (15)O3—C15—H15A109.3 (11)
C5—C6—H6120.3 (10)C16—C15—H15A111.9 (11)
C1—C6—H6118.7 (10)O3—C15—H15B107.7 (12)
O2—C7—H7A113.0 (12)C16—C15—H15B109.9 (12)
O2—C7—H7B110.8 (11)H15A—C15—H15B109.9 (17)
H7A—C7—H7B105.2 (17)C15—C16—H16A109.9 (15)
O2—C7—H7C103.0 (11)C15—C16—H16B113.3 (16)
H7A—C7—H7C113.8 (16)H16A—C16—H16B107 (2)
H7B—C7—H7C111.3 (15)C15—C16—H16C110.6 (13)
N1—C8—C1121.24 (14)H16A—C16—H16C108 (2)
N1—C8—H8123.9 (10)H16B—C16—H16C107 (2)
C1—C8—H8114.9 (10)C8—N1—C9121.49 (13)
C10—C9—C14118.40 (14)C2—O1—H1106.1 (14)
C10—C9—N1124.26 (13)C5—O2—C7117.78 (14)
C14—C9—N1117.20 (13)C12—O3—C15117.91 (12)
C9—C10—C11121.23 (14)
C6—C1—C2—O1179.03 (14)C9—C10—C11—C120.7 (3)
C8—C1—C2—O11.0 (2)C10—C11—C12—O3178.28 (15)
C6—C1—C2—C3−0.4 (2)C10—C11—C12—C13−0.7 (2)
C8—C1—C2—C3−178.42 (15)O3—C12—C13—C14−178.05 (15)
O1—C2—C3—C4−179.32 (15)C11—C12—C13—C141.0 (2)
C1—C2—C3—C40.2 (3)C12—C13—C14—C9−1.3 (3)
C2—C3—C4—C50.8 (3)C10—C9—C14—C131.3 (2)
C3—C4—C5—C6−1.5 (3)N1—C9—C14—C13177.16 (14)
C3—C4—C5—O2177.91 (16)C1—C8—N1—C9174.64 (13)
O2—C5—C6—C1−178.13 (15)C10—C9—N1—C8−27.7 (2)
C4—C5—C6—C11.2 (2)C14—C9—N1—C8156.79 (15)
C2—C1—C6—C5−0.3 (2)C6—C5—O2—C72.3 (3)
C8—C1—C6—C5177.78 (14)C4—C5—O2—C7−177.08 (18)
C2—C1—C8—N1−1.0 (2)C11—C12—O3—C158.4 (2)
C6—C1—C8—N1−179.00 (14)C13—C12—O3—C15−172.62 (16)
C14—C9—C10—C11−1.0 (2)C16—C15—O3—C12179.78 (18)
N1—C9—C10—C11−176.53 (15)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O1—H1···N10.93 (3)1.75 (3)2.5962 (18)149 (2)
C10—H10···O1i0.965 (18)2.571 (18)3.3801 (19)141.5 (13)

Symmetry codes: (i) x, y, z+1.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: EZ2189).

References

  • Farrugia, L. J. (1997). J. Appl. Cryst.30, 565.
  • Farrugia, L. J. (1999). J. Appl. Cryst.32, 837–838.
  • Özek, A., Albayrak, Ç. & Büyükgüngör, O. (2009). Acta Cryst. E65, o2153. [PMC free article] [PubMed]
  • Özek, A., Albayrak, Ç., Odabaşoğlu, M. & Büyükgüngör, O. (2007). Acta Cryst. C63, o177–o180. [PubMed]
  • Özek, A., Büyükgüngör, O., Albayrak, Ç. & Odabaşoğlu, M. (2008). Acta Cryst. E64, o1579–o1580. [PMC free article] [PubMed]
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Stoe & Cie (2002). X-AREA and X-RED32 Stoe & Cie, Darmstadt, Germany.

Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of International Union of Crystallography