X-ray and computational structural study of (E)-2-(4-chloro­phenyl­imino­meth­yl)-4-methoxy­phenol

Arzu Özek; Orhan Büyükgüngör; Çiğdem Albayrak; Mustafa Odabaşoğlu

doi:10.1107/S1600536808023416

. 2008 Jul 31;64(Pt 8):o1613–o1614. doi: 10.1107/S1600536808023416

X-ray and computational structural study of (E)-2-(4-chlorophenyliminomethyl)-4-methoxyphenol

Arzu Özek ^a, Orhan Büyükgüngör ^a,^*, Çiğdem Albayrak ^b, Mustafa Odabaşoğlu ^b

PMCID: PMC2962225 PMID: 21203306

Abstract

In the molecule of the title compound, C₁₄H₁₂ClNO₂, the two aromatic rings are oriented at a dihedral angle of 5.92 (7)°. An intramolecular O—H⋯N hydrogen bond results in the formation of a nearly planar six-membered ring, which is oriented at dihedral angles of 1.55 (4) and 5.95 (4)° with respect to the phenol and chlorophenyl rings, respectively. In the crystal structure, weak intermolecular C—H⋯O hydrogen bonds link the molecules into a three-dimensional network.

Related literature

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 ▶). For general background, see: Friesner (2005 ▶); Liu et al. (2004 ▶).

Experimental

Crystal data

C₁₄H₁₂ClNO₂
M _r = 261.70
Monoclinic,
a = 21.2642 (19) Å
b = 4.7101 (3) Å
c = 12.2175 (12) Å
β = 93.361 (8)°
V = 1221.56 (18) Å³
Z = 4
Mo Kα radiation
μ = 0.30 mm⁻¹
T = 296 K
0.68 × 0.44 × 0.21 mm

Data collection

Stoe IPDSII diffractometer
Absorption correction: integration (X-RED32; Stoe & Cie, 2002 ▶) T _min = 0.825, T _max = 0.925
10205 measured reflections
2364 independent reflections
1789 reflections with I > 2σ(I)
R _int = 0.080

Refinement

R[F ² > 2σ(F ²)] = 0.037
wR(F ²) = 0.099
S = 1.00
2364 reflections
167 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.20 e Å⁻³
Δρ_min = −0.20 e Å⁻³

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, 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 ▶) and GAUSSIAN (Frisch et al., 2004 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808023416/hk2503sup1.cif

e-64-o1613-sup1.cif^{(16.9KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808023416/hk2503Isup2.hkl

e-64-o1613-Isup2.hkl^{(113.8KB, hkl)}

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

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯N1	0.88 (3)	1.79 (3)	2.6210 (18)	157 (2)
C7—H7C⋯O2ⁱ	0.96	2.56	3.495 (2)	164

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Symmetry code: (i) Inline graphic .

Table 2. Selected geometric parameters (Å, °) calculated with X-RAY, AM1, PM3, HF and DFT .

Parameters	X-RAY	AM1	PM3	HF^a	DFT/B3LYP^a
C8—N1	1.276 (19)	1.292	1.302	1.262	1.293
C2—O1	1.355418)	1.368	1.357	1.336	1.344
C1—C6	1.396 (2)	1.406	1.401	1.393	1.406
C1—C8	1.448 (2)	1.466	1.459	1.467	1.449
C1—C2	1.397 (2)	1.408	1.411	1.402	1.423
N1—C9	1.418 (19)	1.409	1.431	1.408	1.406
C9—C10	1.384 (2)	1.414	1.401	1.391	1.403
C12—Cl1	1.734 (15)	1.699	1.684	1.743	1.758
C5—O2	1.3756 (18)	1.385	1.386	1.355	1.371
C11—C12—Cl1	120.72 (12)	119.860	119.505	119.595	119.538
C6—C5—O2	115.56 (14)	114.847	113.926	116.374	116.232
C6—C1—C8	119.18 (13)	116.153	118.078	118.004	119.327
C9—N1 —C8	121.22 (13)	121.780	122.176	120.342	121.253
C14—C9—N1	124.68 (13)	123.445	122.813	122.881	123.392
N1—C8—C1	122.35 (14)	123.800	119.635	123.408	122.250
N1—C9—C10	117.10 (13)	117.991	116.829	118.015	117.770
C8—C1—C2—O1	−0.9 (2)	−0.050	−0.030	−0.111	−0.085
C6—C5—O2—C7	−172.96 (15)	179.476	179.983	179.698	−179.874
C10—C9—N1—C8	−172.84 (13)	−149.450	179.999	62.793	−147.450
N1—C8—C1—C6	177.90 (14)	−177.484	−0.066	−179.307	−179.448
C1—C8—N1—C9	−178.85 (13)	−179.157	179.991	−178.540	−177.303

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Notes: (a) 6-31G(d,p).

Acknowledgments

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).

supplementary crystallographic information

Comment

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 intramolecular 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 and 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-benzimidazole- monohydrate, (II) [where the corresponding values are 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 thermochromic properties in (I) caused by the planarity of the molecule; the dihedral angle between rings A (C1-C6) and B (C9-C14) is 5.92 (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 = 1.55 (4)° and B/C = 5.95 (4)°. So, it is coplanar with the adjacent ring A. It generates an S(6) ring motif. The O1···N1 [2.621 (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) link the molecules into a three-dimensional network (Fig. 2), in which they may be effective in the stabilization of the structure.

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.

Experimental

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 4-chloraniline (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; 76%, m.p. 378-379 K).