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Acta Cryst. (2009). E65, o791    [ doi:10.1107/S1600536809009192 ]

(E)-4-Methoxy-2-(o-tolyliminomethyl)phenol

A. Özek, O. Büyükgüngör, Ç. Albayrak and M. Odabasoglu

Abstract top

In the molecule of the title compound, C15H15NO2, the aromatic rings are oriented at a dihedral angle of 15.46 (6)°. An intramolecular O-H...N hydrogen bond results in the formation of a nearly planar six-membered ring [maximum deviation of 0.035 (5) Å for the N atom] which is almost coplanar with the adjacent ring, making a dihedral angle of 0.8 (3)°. The title organic molecule is a phenol-imine tautomer, as evidenced by the C-O, C-N and C-C bond lengths. Molecules are linked by intermolecular C-H...O hydrogen bonds that generate a C(5) chain. C-H...[pi] and [pi]-[pi] interactions exist in the structure. The [pi]-[pi] interaction occurs between the phenol ring and its symmetry equivalent at (1 - x, 1 - y, -z), with a centroid-centroid distance of 3.727 (7) Å and a plane-to-plane separation of 3.383 (5) Å, resulting in an offset angle of 24.82 (1)°.

Comment top

The present work is part of a structural study of Schiff bases (Özek et al., 2007; Odabaşoğlu, Büyükgüngör et al., 2007; Odabaşoğlu, Arslan et al., 2007) and we report here the structure of (E)-4-methoxy-2-[(o-tolylimino)methyl]phenol, (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. The H atom in title compound (I) is located on atom O1, thus the phenol-imine tautomer is favored over the keto-amine form, as indicated by the C2—O1 [1.3579 (2) Å], C8—N1 [1.2865 (2) Å], C1—C8 [1.4519 (2) Å] and C1—C2 [1.4071 (2) Å] bond lengths (Fig. 1). The C2—O1 bond length of 1.357 (2)Å indicates single-bond character, whereas the C8—N1 bond length of 1.286 (2)Å indicates a high degree of double-bond character. Similar results were observed for 2-(3-methoxysalicylideneamino)-1H-benzimidazolemonohydrate [C—O=1.357 (2) Å, C—N= 1.285 (2) Å, Albayrak et al., 2005].

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 rings A(C1—C6) and B (C9—C14) is 15.46 (6)°. 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), oriented with respect to rings A and B at dihedral angles of A/C=0.81 (2)° and B/C= 15.04 (3)°. So, it is coplanar with the adjacent ring A and generates an S(6) ring motif. The O1···N1 distance of 2.579 (2)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 results in the formation of C(5) chains along the c axis (Table 1, Fig. 2). In addition to these intermolecular interactions, C—H···π interactions and π···π interactions play roles in the crystal packing (Table 1, Fig. 3). This slipped π···π interaction occurs between Cg1 (the centroid of the C1—C6 ring) and its symmetry equivalent at (1 - x, 1 - y, -z), with a centroid-to-centroid distance of 3.727 (7)Å and a plane-to-plane separation of 3.383 (5) Å, resulting in an offset angle of 24.82 (1)°.

Related literature top

For related literature, see: Özek et al. (2007); Albayrak et al. (2005); Odabaşoğlu, Arslan et al. (2007); Odabaşoğlu, Büyükgüngör et al. (2007).

Experimental top

The compound (E)-4-methoxy-2-[(o-tolylimino)methyl]phenol was prepared by reflux a mixture of a solution containing 5-methoxysalicylaldehyde (0.5 g 3.3 mmol) in 20 ml ethanol and a solution containing 2-chloraniline (0.420 g 3.3 mmol) in 20 ml ethanol. The reaction mixture was stirred for 1 h under reflux. The crystals of (E)-4-methoxy-2-[(o-tolylimino)methyl]phenol suitable for X-ray analysis were obtained from methanol by slow evaporation (yield % 73; m.p. 343–344 K).

Refinement top

All the H-atoms were found in difference-density maps, and refined freely. The C—H bond lengths are 0.95 (2)–0.99 (2) Å.

Computing details top

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

Figures top
[Figure 1] Fig. 1. A view of (I), with the atom-numbering scheme and 30% probability displacement ellipsoids. Dashed line indicates intramolecular hydrogen bond.
[Figure 2] Fig. 2. A partial packing view of (I), showing the formation of the C(5) chain through C—H···O intermolecular hydrogen bonds. Dashed lines indicate hydrogen bonds. H atoms not involved in hydrogen bonding have been omitted for clarity. [Symmetry code: (i) x, -y + 3/2, z + 1/2].
[Figure 3] Fig. 3. A partial packing view of (I), showing the intermolecular C—H···π and π···π interactions as dashed lines. H atoms not involved in hydrogen bonding have been omitted for clarity. [Symmetry codes; (i): 1 - x, -y + 2, 1 - z; (ii): 1 - x, 1 - y, 1 - z].
(E)-4-Methoxy-2-(o-tolyliminomethyl)phenol top
Crystal data top
C15H15NO2F(000) = 512
Mr = 241.28Dx = 1.308 Mg m−3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 6569 reflections
a = 13.2889 (6) Åθ = 1.9–28.0°
b = 8.5986 (6) ŵ = 0.09 mm−1
c = 11.6714 (6) ÅT = 100 K
β = 113.284 (3)°Prism, red
V = 1225.03 (12) Å30.59 × 0.47 × 0.30 mm
Z = 4
Data collection top
Stoe IPDS II
diffractometer		2537 independent reflections
Radiation source: fine-focus sealed tube2108 reflections with I > 2σ(I)
plane graphiteRint = 0.039
Detector resolution: 6.67 pixels mm-1θmax = 26.5°, θmin = 2.9°
ω scansh = −16→16
Absorption correction: integration
(X-RED32; Stoe & Cie, 2002)		k = −9→10
Tmin = 0.954, Tmax = 0.975l = −14→13
6569 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.036Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.092H atoms treated by a mixture of independent and constrained refinement
S = 1.02 w = 1/[σ2(Fo2) + (0.0457P)2 + 0.2485P]
where P = (Fo2 + 2Fc2)/3
2537 reflections(Δ/σ)max < 0.001
223 parametersΔρmax = 0.20 e Å−3
0 restraintsΔρmin = −0.19 e Å−3
Crystal data top
C15H15NO2V = 1225.03 (12) Å3
Mr = 241.28Z = 4
Monoclinic, P21/cMo Kα radiation
a = 13.2889 (6) ŵ = 0.09 mm−1
b = 8.5986 (6) ÅT = 100 K
c = 11.6714 (6) Å0.59 × 0.47 × 0.30 mm
β = 113.284 (3)°
Data collection top
Stoe IPDS II
diffractometer		2537 independent reflections
Absorption correction: integration
(X-RED32; Stoe & Cie, 2002)		2108 reflections with I > 2σ(I)
Tmin = 0.954, Tmax = 0.975Rint = 0.039
6569 measured reflectionsθmax = 26.5°
Refinement top
R[F2 > 2σ(F2)] = 0.036H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.092Δρmax = 0.20 e Å−3
S = 1.02Δρmin = −0.19 e Å−3
2537 reflectionsAbsolute structure: ?
223 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

Experimental. 133 frames, detector distance = 80 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) top
xyzUiso*/Ueq
C10.50912 (9)0.80474 (14)0.44057 (10)0.0202 (2)
C20.50739 (9)0.87880 (14)0.33229 (10)0.0220 (3)
C30.41277 (10)0.95544 (15)0.25458 (11)0.0260 (3)
C40.32140 (10)0.95800 (15)0.28313 (11)0.0268 (3)
C50.32211 (9)0.88566 (14)0.39055 (11)0.0240 (3)
C60.41552 (9)0.80964 (14)0.46900 (11)0.0221 (3)
C70.22417 (11)0.82076 (17)0.51644 (13)0.0301 (3)
C80.60665 (9)0.72552 (14)0.52526 (10)0.0204 (2)
C90.78609 (9)0.62921 (13)0.57661 (10)0.0199 (2)
C100.88252 (9)0.65581 (14)0.55698 (10)0.0220 (3)
C110.97626 (10)0.57301 (15)0.62954 (11)0.0253 (3)
C120.97591 (10)0.46596 (15)0.71788 (11)0.0273 (3)
C130.87983 (10)0.43903 (15)0.73477 (11)0.0267 (3)
C140.78528 (10)0.52031 (15)0.66497 (11)0.0238 (3)
C150.88540 (10)0.77174 (16)0.46210 (13)0.0271 (3)
N10.69160 (8)0.71244 (11)0.49897 (9)0.0201 (2)
O10.59622 (7)0.88000 (11)0.30225 (8)0.0259 (2)
O20.22688 (7)0.89755 (11)0.40973 (9)0.0299 (2)
H10.6488 (15)0.821 (2)0.3689 (18)0.052 (5)*
H30.4132 (12)1.0039 (19)0.1796 (14)0.034 (4)*
H40.2560 (12)1.0104 (19)0.2304 (14)0.034 (4)*
H60.4193 (11)0.7593 (18)0.5449 (14)0.027 (3)*
H7A0.2795 (12)0.8655 (18)0.5964 (14)0.030 (4)*
H7B0.2372 (13)0.705 (2)0.5150 (15)0.038 (4)*
H80.6040 (11)0.6867 (17)0.6023 (14)0.026 (3)*
H111.0416 (12)0.5929 (17)0.6150 (13)0.030 (4)*
H121.0432 (12)0.4111 (18)0.7671 (14)0.032 (4)*
H130.8786 (12)0.3638 (19)0.7957 (14)0.033 (4)*
H140.7188 (12)0.4974 (18)0.6756 (13)0.028 (4)*
H15A0.9547 (15)0.772 (2)0.4543 (16)0.046 (5)*
H15B0.8291 (13)0.7525 (19)0.3784 (15)0.036 (4)*
H7C0.1484 (13)0.838 (2)0.5114 (15)0.039 (4)*
H15C0.8706 (14)0.879 (2)0.4830 (16)0.048 (5)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0214 (5)0.0197 (6)0.0185 (5)−0.0007 (4)0.0068 (4)−0.0023 (4)
C20.0249 (5)0.0209 (6)0.0206 (5)−0.0010 (5)0.0093 (4)−0.0025 (4)
C30.0313 (6)0.0239 (6)0.0201 (5)0.0010 (5)0.0072 (5)0.0020 (5)
C40.0238 (6)0.0249 (6)0.0256 (6)0.0033 (5)0.0033 (5)0.0004 (5)
C50.0205 (5)0.0221 (6)0.0287 (6)−0.0003 (5)0.0088 (5)−0.0041 (5)
C60.0242 (6)0.0211 (6)0.0212 (5)0.0006 (5)0.0091 (4)−0.0002 (4)
C70.0252 (6)0.0313 (7)0.0381 (7)−0.0007 (5)0.0172 (5)−0.0039 (6)
C80.0234 (5)0.0203 (6)0.0179 (5)−0.0002 (4)0.0083 (4)−0.0015 (4)
C90.0211 (5)0.0196 (6)0.0177 (5)0.0012 (4)0.0063 (4)−0.0034 (4)
C100.0235 (5)0.0193 (6)0.0223 (5)−0.0004 (4)0.0083 (4)−0.0038 (5)
C110.0200 (5)0.0250 (6)0.0297 (6)−0.0005 (5)0.0086 (5)−0.0034 (5)
C120.0239 (6)0.0277 (7)0.0255 (6)0.0053 (5)0.0047 (5)−0.0011 (5)
C130.0325 (6)0.0258 (6)0.0221 (6)0.0053 (5)0.0112 (5)0.0036 (5)
C140.0248 (6)0.0248 (6)0.0231 (5)0.0020 (5)0.0110 (4)−0.0002 (5)
C150.0240 (6)0.0274 (7)0.0326 (7)0.0012 (5)0.0139 (5)0.0033 (5)
N10.0209 (5)0.0197 (5)0.0194 (4)0.0007 (4)0.0076 (4)−0.0012 (4)
O10.0280 (4)0.0300 (5)0.0229 (4)0.0028 (4)0.0135 (3)0.0043 (4)
O20.0206 (4)0.0305 (5)0.0391 (5)0.0038 (4)0.0122 (4)0.0027 (4)
Geometric parameters (Å, °) top
C1—C21.4071 (16)C8—H80.973 (15)
C1—C61.4091 (16)C9—C141.3961 (17)
C1—C81.4519 (16)C9—C101.4068 (16)
C2—O11.3579 (14)C9—N11.4179 (14)
C2—C31.3916 (17)C10—C111.3934 (16)
C3—C41.3805 (18)C10—C151.5017 (17)
C3—H30.971 (16)C11—C121.3836 (18)
C4—C51.3962 (18)C11—H110.963 (16)
C4—H40.956 (16)C12—C131.3862 (18)
C5—O21.3734 (15)C12—H120.973 (15)
C5—C61.3812 (17)C13—C141.3862 (17)
C6—H60.969 (15)C13—H130.966 (16)
C7—O21.4226 (17)C14—H140.959 (15)
C7—H7A1.008 (15)C15—H15A0.960 (18)
C7—H7B1.008 (18)C15—H15B0.981 (16)
C7—H7C0.996 (17)C15—H15C0.99 (2)
C8—N11.2865 (15)O1—H10.958 (19)
C2—C1—C6119.70 (10)C14—C9—C10120.19 (10)
C2—C1—C8121.13 (10)C14—C9—N1123.17 (10)
C6—C1—C8119.16 (10)C10—C9—N1116.58 (10)
O1—C2—C3118.81 (11)C11—C10—C9118.10 (11)
O1—C2—C1121.88 (10)C11—C10—C15120.67 (11)
C3—C2—C1119.30 (11)C9—C10—C15121.22 (10)
C4—C3—C2120.30 (11)C12—C11—C10121.82 (11)
C4—C3—H3122.0 (9)C12—C11—H11121.2 (9)
C2—C3—H3117.7 (9)C10—C11—H11117.0 (9)
C3—C4—C5121.02 (11)C11—C12—C13119.45 (11)
C3—C4—H4120.9 (9)C11—C12—H12119.3 (9)
C5—C4—H4118.0 (9)C13—C12—H12121.2 (9)
O2—C5—C6124.87 (11)C12—C13—C14120.27 (12)
O2—C5—C4115.69 (11)C12—C13—H13120.1 (9)
C6—C5—C4119.43 (11)C14—C13—H13119.6 (9)
C5—C6—C1120.25 (11)C13—C14—C9120.16 (11)
C5—C6—H6121.7 (8)C13—C14—H14119.2 (9)
C1—C6—H6118.1 (8)C9—C14—H14120.6 (9)
O2—C7—H7A111.8 (9)C10—C15—H15A112.1 (11)
O2—C7—H7B112.2 (9)C10—C15—H15B112.9 (10)
H7A—C7—H7B108.9 (13)H15A—C15—H15B106.8 (14)
O2—C7—H7C104.7 (9)C10—C15—H15C111.7 (10)
H7A—C7—H7C110.4 (13)H15A—C15—H15C108.2 (15)
H7B—C7—H7C108.8 (13)H15B—C15—H15C104.7 (14)
N1—C8—C1120.66 (10)C8—N1—C9122.05 (10)
N1—C8—H8123.1 (8)C2—O1—H1102.5 (11)
C1—C8—H8116.2 (8)C5—O2—C7116.87 (9)
C6—C1—C2—O1178.64 (11)N1—C9—C10—C11−178.42 (10)
C8—C1—C2—O1−0.16 (17)C14—C9—C10—C15179.71 (11)
C6—C1—C2—C3−0.23 (17)N1—C9—C10—C152.50 (16)
C8—C1—C2—C3−179.03 (11)C9—C10—C11—C120.70 (18)
O1—C2—C3—C4−179.26 (11)C15—C10—C11—C12179.77 (12)
C1—C2—C3—C4−0.36 (18)C10—C11—C12—C130.37 (19)
C2—C3—C4—C50.67 (19)C11—C12—C13—C14−0.92 (19)
C3—C4—C5—O2179.29 (11)C12—C13—C14—C90.40 (18)
C3—C4—C5—C6−0.38 (19)C10—C9—C14—C130.69 (17)
O2—C5—C6—C1−179.85 (11)N1—C9—C14—C13177.71 (11)
C4—C5—C6—C1−0.21 (18)C1—C8—N1—C9−176.83 (10)
C2—C1—C6—C50.51 (17)C14—C9—N1—C818.82 (17)
C8—C1—C6—C5179.34 (11)C10—C9—N1—C8−164.07 (11)
C2—C1—C8—N1−4.59 (17)C6—C5—O2—C7−2.26 (17)
C6—C1—C8—N1176.60 (11)C4—C5—O2—C7178.09 (11)
C14—C9—C10—C11−1.22 (17)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O1—H1···N10.958 (19)1.68 (2)2.5794 (13)154.8 (17)
C8—H8···O1i0.973 (15)2.444 (15)3.4129 (14)173.5 (12)
C7—H7B···Cg2ii1.008 (18)2.903 (17)3.6727 (16)134.1 (16)
Symmetry codes: (i) x, −y+3/2, z+1/2; (ii) −x+1, −y, −z.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O1—H1···N10.958 (19)1.68 (2)2.5794 (13)154.8 (17)
C8—H8···O1i0.973 (15)2.444 (15)3.4129 (14)173.5 (12)
C7—H7B···Cg2ii1.008 (18)2.903 (17)3.6727 (16)134.1 (16)
Symmetry codes: (i) x, −y+3/2, z+1/2; (ii) −x+1, −y, −z.
Acknowledgements top

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 No. F.279 of the University Research Fund).

references
References top

Albayrak, Ç., Odabaşoğlu, M. & Büyükgüngör, O. (2005). Acta Cryst. E61, o423–o424.

Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.

Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838.

Odabaşoğlu, M., Arslan, F., Ölmez, H. & Büyükgüngör, O. (2007). Acta Cryst. E63, o3654.

Odabaşoğlu, M., Büyükgüngör, O., Narayana, B., Vijesh, A. M. & Yathirajan, H. S. (2007). Acta Cryst. E63, o1916–o1918.

Özek, A., Albayrak, Ç., Odabaşoğlu, M. & Büyükgüngör, O. (2007). Acta Cryst. C63, o177–o180.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.

Stoe & Cie (2002). X-AREA and X-RED32. Stoe & Cie, Darmstadt, Germany.