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Acta Cryst. (2008). E64, o1579-o1580    [ doi:10.1107/S1600536808021958 ]

X-ray crystal and computational structural study of (E)-2-[(2-chlorophenyl)iminomethyl]-4-methoxyphenol

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

Abstract top

In the molecule of the title compound, C14H12ClNO, the two aromatic rings are oriented at a dihedral angle of 12.28 (7)°. An intramolecular O-H...N hydrogen bond results in the formation of a nearly planar six-membered ring, which is oriented with respect to the aromatic rings at dihedral angles of 0.18 (5) and 12.10 (6)°. In the crystal structure, weak intermolecular C-H...O hydrogen bonds link the molecules into chains along the c axis. There is a C-H...[pi] contact between the methyl group and the chlorophenyl ring and a [pi]-[pi] contact between the two benzene rings [centroid-centroid distance = 3.866 (1) Å].

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). We report herein the crystal structure of the title compound, (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 (I) 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 bonds (Fig. 1, Table 2). The O1-C2 bond has single-bond character, whereas the N1-C8 bond has a high degree of double-bond character as in 2-(3-methoxysalicylideneamino)-1H -benzimidazolemonohydrate, (II) [where the corresponding values are C-O = 1.357 (2) Å and 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 thermochromic properties in (I) caused by the planarity of the molecule; the dihedral angle between rings A (C1-C6) and B (C9-C14) is 12.28 (7)°. 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 = 0.18 (5)° and B/C = 12.10 (6)°. So, it is coplanar with the adjacent ring A. It generates an S(6) ring motif. The O1···N1 [2.589 (2) Å] distance is comparable to those observed for analogous ones in N-(2-hydroxyphenyl)salicylaldimine, (III) [2.675 (7) Å; Elerman et al., 1995] and in three(E)-2-[(bromophenyl)iminomethyl]-4-methoxyphenols, (IV) [2.603 (2), 2.638 (7) and 2.577 (4) Å;Özek et al., 2007].

In the crystal structure, weak intermolecular C-H···O hydrogen bonds (Table 1) results in the formation of C(5) chains along the c axis (Fig. 2), in which they may be effective in the stabilization of the structure. A C—H···π contact (Table 1) between the methyl group and ring B and a π—π contact (Fig. 3) between the symmetry related A rings Cg1···Cg1i [symmetry code: (i) 1 - x, 1 - y, - z, where Cg1 is the centroid of ring A] further stabilize the structure, with centroid-centroid distance of 3.866 (1) Å.

Ab-initio Hartree-Fock (HF), density-functional theory (DFT) and semi-empirical (AM1 and PM3) calculations and full-geometry optimizations were performed by means of GAUSSIAN 03 W package (Frisch et al., 2004). The selected bond lengths and angles together with the torsion angles are compared with the obtained ones from semi-empirical, ab-initio HF and DFT/B3LYP methods (Table 2). We observe an acceptable general agreement between them. Although the DFT molecular orbital theory was considered as the most accurate method for geometry optimization for free and complex ligands (Friesner, 2005; Liu et al., 2004), the HF method led to better results in regard to the bond lengths and angles.

Related literature top

For related literature, see: Özek et al. (2007); Odabaşoğlu, Büyükgüngör et al. (2007); Odabaşoğlu, Arslan et al. (2007); Albayrak et al. (2005); Elerman et al. (1995); Frisch et al. (2004). For general background, see: Friesner (2005); Liu et al. (2004).

Experimental top

The title compound was prepared by refluxing a mixture of a solution containing 5-methoxysalicylaldehyde (0.5 g 3.3 mmol) in ethanol (20 ml) and a solution containing 2-chloroaniline (0.420 g 3.3 mmol) in ethanol (20 ml). The reaction mixture was stirred for 1 h, under reflux. The crystals suitable for X-ray analysis were obtained from ethanol by slow evaporation (yield; 75%; m.p. 393-394 K).

Refinement top

H1 atom (for OH) was located in difference syntheses and refined isotropically [O-H = 0.80 (2) Å and Uiso(H) = 0.082 (6) Å2]. The remaining H atoms were positioned geometrically, with C-H = 0.93 and 0.96 Å for aromatic and methyl H, respectively, and constrained to ride on their parent atoms with Uiso(H) = 1.2Ueq(C).

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. The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 20% probability level. Hydrogen bond is shown as dashed line.
[Figure 2] Fig. 2. A partial packing diagram of (I), showing the formation of C(5) chains [symmetry code: (i) x, -y + 3/2, z + 1/2]. Hydrogen bonds are shown as dashed lines. H atoms not involved in hydrogen bonding have been omitted for clarity.
[Figure 3] Fig. 3. A partial packing diagram of (I), showing the formation of the C—H···π and π···π interactions [symmetry codes; (i) 1 - x, 1 - y, - z; (ii) 1 - x, 1 - y, 1 - z]. Hydrogen bonds are shown as dashed lines. H atoms not involved in hydrogen bonding have been omitted for clarity.
(E)-2-[(2-chlorophenyl)iminomethyl]-4-methoxyphenol top
Crystal data top
C14H12ClNO2F000 = 544
Mr = 261.70Dx = 1.401 Mg m−3
Monoclinic, P21/cMo Kα radiation
λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 15517 reflections
a = 13.2348 (9) Åθ = 2.0–28.0º
b = 8.4701 (4) ŵ = 0.30 mm−1
c = 12.0115 (8) ÅT = 296 K
β = 112.846 (5)ºPrismatic plate, red
V = 1240.86 (13) Å30.56 × 0.40 × 0.11 mm
Z = 4
Data collection top
Stoe IPDSII
diffractometer		2441 independent reflections
Radiation source: fine-focus sealed tube1977 reflections with I > 2σ(I)
Monochromator: plane graphiteRint = 0.042
Detector resolution: 6.67 pixels mm-1θmax = 26.0º
T = 296 Kθmin = 2.9º
ω scansh = −16→16
Absorption correction: integration
(X-RED32; Stoe & Cie, 2002)		k = −10→10
Tmin = 0.851, Tmax = 0.966l = −14→14
15517 measured reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.031H atoms treated by a mixture of
independent and constrained refinement
wR(F2) = 0.089  w = 1/[σ2(Fo2) + (0.0523P)2 + 0.0594P]
where P = (Fo2 + 2Fc2)/3
S = 1.05(Δ/σ)max = 0.001
2441 reflectionsΔρmax = 0.13 e Å−3
167 parametersΔρmin = −0.21 e Å−3
Primary atom site location: structure-invariant direct methodsExtinction correction: none
Crystal data top
C14H12ClNO2V = 1240.86 (13) Å3
Mr = 261.70Z = 4
Monoclinic, P21/cMo Kα
a = 13.2348 (9) ŵ = 0.30 mm−1
b = 8.4701 (4) ÅT = 296 K
c = 12.0115 (8) Å0.56 × 0.40 × 0.11 mm
β = 112.846 (5)º
Data collection top
Stoe IPDSII
diffractometer		2441 independent reflections
Absorption correction: integration
(X-RED32; Stoe & Cie, 2002)		1977 reflections with I > 2σ(I)
Tmin = 0.851, Tmax = 0.966Rint = 0.042
15517 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.031167 parameters
wR(F2) = 0.089H atoms treated by a mixture of
independent and constrained refinement
S = 1.05Δρmax = 0.13 e Å−3
2441 reflectionsΔρmin = −0.21 e Å−3
Special details top

Experimental. 336 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 > 2sigma(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
Cl10.11627 (3)0.76700 (5)0.55086 (4)0.06604 (15)
O10.40106 (9)0.86945 (14)0.69518 (11)0.0623 (3)
H10.3554 (17)0.822 (2)0.641 (2)0.082 (6)*
O20.77703 (8)0.90497 (15)0.60329 (11)0.0728 (3)
N10.31117 (9)0.70603 (13)0.49903 (10)0.0454 (3)
C10.49336 (10)0.80152 (15)0.56335 (12)0.0445 (3)
C20.49138 (11)0.87192 (16)0.66786 (13)0.0494 (3)
C30.58388 (13)0.95011 (19)0.74523 (14)0.0599 (4)
H30.58310.99780.81460.072*
C40.67628 (12)0.95805 (19)0.72077 (14)0.0619 (4)
H40.73771.01090.77390.074*
C50.67990 (11)0.88837 (17)0.61772 (14)0.0547 (3)
C60.58916 (11)0.81123 (16)0.53942 (13)0.0501 (3)
H60.59090.76500.47000.060*
C70.78611 (14)0.8339 (2)0.50131 (18)0.0726 (5)
H7A0.73130.87680.42910.087*
H7B0.77560.72200.50370.087*
H7C0.85760.85440.50180.087*
C80.39782 (11)0.72290 (15)0.47745 (12)0.0457 (3)
H80.39950.68420.40570.055*
C90.21762 (10)0.62666 (15)0.41915 (12)0.0443 (3)
C100.12031 (11)0.64486 (15)0.43678 (13)0.0479 (3)
C110.02522 (11)0.56821 (18)0.36454 (15)0.0595 (4)
H11−0.03910.58280.37730.071*
C120.02614 (12)0.47049 (19)0.27390 (15)0.0637 (4)
H12−0.03760.41880.22490.076*
C130.12142 (13)0.4492 (2)0.25577 (14)0.0629 (4)
H130.12200.38190.19480.075*
C140.21635 (12)0.52647 (17)0.32687 (13)0.0548 (3)
H140.28010.51140.31300.066*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0411 (7)0.0489 (7)0.0414 (7)−0.0018 (5)0.0136 (5)0.0020 (5)
C20.0508 (7)0.0523 (7)0.0453 (7)−0.0019 (6)0.0190 (6)0.0008 (6)
C30.0626 (9)0.0646 (9)0.0469 (8)−0.0067 (7)0.0153 (7)−0.0092 (7)
C40.0500 (8)0.0653 (9)0.0580 (9)−0.0116 (7)0.0075 (7)−0.0067 (7)
C50.0406 (7)0.0569 (8)0.0624 (9)−0.0023 (6)0.0154 (6)0.0041 (7)
C60.0452 (7)0.0553 (7)0.0495 (8)−0.0023 (6)0.0180 (6)−0.0003 (6)
C70.0531 (9)0.0848 (11)0.0877 (12)−0.0008 (8)0.0358 (9)0.0109 (10)
C80.0453 (7)0.0523 (7)0.0395 (7)−0.0034 (5)0.0164 (5)0.0004 (5)
C90.0422 (7)0.0460 (6)0.0422 (7)−0.0028 (5)0.0135 (5)0.0062 (5)
C100.0451 (7)0.0468 (7)0.0511 (8)−0.0005 (5)0.0179 (6)0.0037 (6)
C110.0410 (7)0.0591 (8)0.0747 (10)−0.0029 (6)0.0184 (7)0.0021 (7)
C120.0500 (8)0.0664 (9)0.0622 (10)−0.0138 (7)0.0082 (7)−0.0034 (7)
C130.0663 (10)0.0682 (9)0.0526 (9)−0.0154 (7)0.0214 (7)−0.0101 (7)
C140.0533 (8)0.0621 (8)0.0525 (8)−0.0088 (6)0.0246 (6)−0.0040 (7)
N10.0406 (6)0.0517 (6)0.0430 (6)−0.0029 (4)0.0153 (5)0.0017 (5)
O10.0597 (7)0.0781 (7)0.0560 (6)−0.0107 (5)0.0301 (5)−0.0142 (6)
O20.0437 (6)0.0865 (8)0.0880 (9)−0.0134 (5)0.0255 (6)−0.0087 (7)
Cl10.0595 (2)0.0677 (2)0.0810 (3)−0.00680 (17)0.0382 (2)−0.01591 (19)
Geometric parameters (Å, °) top
O1—H10.80 (2)C7—H7C0.9600
C1—C21.3992 (19)C8—N11.2781 (17)
C1—C61.4071 (18)C8—H80.9300
C1—C81.4470 (19)C9—C141.3908 (19)
C2—O11.3572 (17)C9—C101.3925 (18)
C2—C31.385 (2)C9—N11.4082 (17)
C3—C41.366 (2)C10—C111.3822 (19)
C3—H30.9300C10—Cl11.7342 (14)
C4—C51.389 (2)C11—C121.371 (2)
C4—H40.9300C11—H110.9300
C5—O21.3694 (17)C12—C131.372 (2)
C5—C61.370 (2)C12—H120.9300
C6—H60.9300C13—C141.379 (2)
C7—O21.411 (2)C13—H130.9300
C7—H7A0.9600C14—H140.9300
C7—H7B0.9600
C2—O1—H1105.4 (15)O2—C7—H7C109.5
C5—O2—C7117.81 (12)H7A—C7—H7C109.5
C8—N1—C9122.41 (12)H7B—C7—H7C109.5
C2—C1—C6119.38 (12)N1—C8—C1120.75 (13)
C2—C1—C8121.36 (12)N1—C8—H8119.6
C6—C1—C8119.24 (13)C1—C8—H8119.6
O1—C2—C3118.51 (13)C14—C9—C10117.58 (12)
O1—C2—C1122.37 (12)C14—C9—N1124.73 (12)
C3—C2—C1119.10 (13)C10—C9—N1117.64 (12)
C4—C3—C2120.75 (14)C11—C10—C9121.54 (13)
C4—C3—H3119.6C11—C10—Cl1118.44 (11)
C2—C3—H3119.6C9—C10—Cl1120.02 (10)
C3—C4—C5120.96 (13)C12—C11—C10119.69 (14)
C3—C4—H4119.5C12—C11—H11120.2
C5—C4—H4119.5C10—C11—H11120.2
O2—C5—C6125.30 (15)C11—C12—C13119.81 (13)
O2—C5—C4115.35 (13)C11—C12—H12120.1
C6—C5—C4119.35 (13)C13—C12—H12120.1
C5—C6—C1120.45 (14)C12—C13—C14120.77 (15)
C5—C6—H6119.8C12—C13—H13119.6
C1—C6—H6119.8C14—C13—H13119.6
O2—C7—H7A109.5C13—C14—C9120.61 (14)
O2—C7—H7B109.5C13—C14—H14119.7
H7A—C7—H7B109.5C9—C14—H14119.7
C6—C1—C2—O1178.75 (13)C4—C5—C6—C1−0.4 (2)
C8—C1—C2—O10.6 (2)C1—C8—N1—C9−178.32 (11)
C6—C1—C2—C30.2 (2)C14—C9—N1—C816.7 (2)
C8—C1—C2—C3−177.93 (13)C10—C9—N1—C8−165.93 (12)
C2—C1—C6—C50.2 (2)C14—C9—C10—C11−0.9 (2)
C8—C1—C6—C5178.38 (13)N1—C9—C10—C11−178.38 (12)
C2—C1—C8—N1−4.9 (2)C14—C9—C10—Cl1179.58 (10)
C6—C1—C8—N1176.91 (12)N1—C9—C10—Cl12.05 (16)
O1—C2—C3—C4−178.98 (14)C10—C9—C14—C130.3 (2)
C1—C2—C3—C4−0.4 (2)N1—C9—C14—C13177.61 (13)
C2—C3—C4—C50.1 (2)C9—C10—C11—C120.6 (2)
C3—C4—C5—O2179.83 (15)Cl1—C10—C11—C12−179.78 (12)
C3—C4—C5—C60.3 (2)C10—C11—C12—C130.2 (2)
C6—C5—O2—C7−1.7 (2)C11—C12—C13—C14−0.7 (2)
C4—C5—O2—C7178.80 (14)C12—C13—C14—C90.5 (2)
O2—C5—C6—C1−179.95 (13)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O1—H1···N10.80 (2)1.85 (2)2.5896 (16)152 (2)
C8—H8···O1i0.932.583.4960 (19)169
C7—H7b···Cg2ii0.962.903.682139.00
Symmetry codes: (i) x, −y+3/2, z−1/2; (ii) −x+1, −y+1, −z+1.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O1—H1···N10.80 (2)1.85 (2)2.5896 (16)152 (2)
C8—H8···O1i0.932.583.4960 (19)169
C7—H7b···Cg2ii0.962.903.682139.00
Symmetry codes: (i) x, −y+3/2, z−1/2; (ii) −x+1, −y+1, −z+1.
Table 2
Selected geometric parameters (Å, °) calculated with X-ray, AM1, PM3, HF and DFT for (I) top
ParametersX-rayAM1PM3HFaDFT/B3LYPa
C8—N11.278 (17)1.2921.3021.2621.294
C2—O11357 (17)1.3661.3551.3321.341
C1—C61.407 (18)1.4121.4061.4081.416
C1—C81.447 (19)1.4651.4781.4631.446
C1—C21.399 (19)1.4041.4081.3921.418
N1—C91.408 (17)1.4081.4271.4021.399
C9—C101.392 (18)1.4171.4021.3931.409
C10—Cl11.734 (14)1.6991.6801.7411.755
C5—-O21.369 (17)1.3851.3851.3541.369
C9—C10—Cl1120.02 (10)120.869120.554120.163119.783
C6—C5—O2125.3 (15)124.874125.684125.547125.410
C6—C1—C8119.24 (13)116.155117.987117.891119.224
C9—N1—C8122.41 (12)121.909122.720120.140121.089
C14—C9—N1124.73 (12)123.114123.424122.078122.787
N1—C8—C1120.75 (13)123.585119.187123.458122.291
N1—C9—C10117.64 (12)118.844116.913119.874119.562
C8—C1—C2—O10.6 (2)-0.0340.012-0.194-0.175
C6—C5—O2—C7-1.7 (2)0.543-0.4850.5680.096
C10—C9—N1—C8-165.93 (12)-147.255-179.982-134.578-144.790
N1—C8—C1—C6176.91 (12)176.946-179.997179.409179.781
C1—C8—N1—C9-178.32 (11)-179.082179.999-178.064-176.682
Notes: (a) 6-31G(d,p).
Acknowledgements top

The authors acknowledge the Faculty of Arts and Sciences, Ondokuz Mayıs University, Turkey, for the use of the Stoe IPDSII diffractometer (purchased under grant No. F.279 of the University Research Fund).

references
References top

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