2-[(4-Bromo­phen­yl)imino­meth­yl]-3,5-dimethoxy­phenol

Işın Kılıç; Erbil Ağar; Ferda Erşahin; Şamil Işık

doi:10.1107/S1600536809011416

. 2009 Mar 31;65(Pt 4):o934. doi: 10.1107/S1600536809011416

2-[(4-Bromophenyl)iminomethyl]-3,5-dimethoxyphenol

Işın Kılıç ^a,^*, Erbil Ağar ^b, Ferda Erşahin ^b, Şamil Işık ^a

PMCID: PMC2968797 PMID: 21582634

Abstract

There are two independent molecules in the asymmetric unit of the title compound, C₁₅H₁₄BrNO₃, with very similar geometrical parameters. Each molecule adopts the phenol–imine tautomeric form, with strong intramolecular O—H⋯N hydrogen bonds. The two molecules are non-planar, the dihedral angles between the two aromatic rings being are 24.6 (2) and 30.30 (13)°.

Related literature

For bond-length data, see: Petek et al. (2007 ▶).

Experimental

Crystal data

C₁₅H₁₄BrNO₃
M _r = 336.18
Triclinic,
a = 8.2655 (5) Å
b = 9.7305 (6) Å
c = 18.3806 (11) Å
α = 97.177 (5)°
β = 92.796 (5)°
γ = 106.214 (5)°
V = 1402.94 (15) Å³
Z = 4
Mo Kα radiation
μ = 2.94 mm⁻¹
T = 296 K
0.67 × 0.38 × 0.09 mm

Data collection

Stoe IPDS-2 diffractometer
Absorption correction: integration (X-RED; Stoe & Cie, 2002 ▶) T _min = 0.421, T _max = 0.839
20096 measured reflections
5514 independent reflections
3901 reflections with I > 2σ(I)
R _int = 0.080

Refinement

R[F ² > 2σ(F ²)] = 0.050
wR(F ²) = 0.112
S = 1.02
5514 reflections
369 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.61 e Å⁻³
Δρ_min = −0.92 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 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809011416/bt2917sup1.cif

e-65-0o934-sup1.cif^{(24.8KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809011416/bt2917Isup2.hkl

e-65-0o934-Isup2.hkl^{(264.5KB, 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	0.97 (5)	1.69 (5)	2.564 (4)	149 (5)
O4—H4⋯N2	0.83 (5)	1.80 (5)	2.564 (4)	150 (5)

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Acknowledgments

The authors acknowledge the Faculty of Arts and Sciences, Ondokuz Mayıs University, Turkey, for the use of the Stoe IPDSI-2 diffractometer (purchased under grant No. F279 of the University Research Fund).

supplementary crystallographic information

Comment

The extensive application of Schiff bases in industry and in analytical determinations has attracted attention for decades. The overall behaviour of these compounds has been ascribed to a proton-transfer reaction between a phenol-imine and a keto-amine tautomer. It is claimed that phenol-imine tautomerism is dominant in salicylaldimine, while the keto-amine form is preferred in naphthaldimine Schiff bases, depending on the solvent polarities. Our X-ray investigation of the title compound has indicated that the phenol-imine tautomer is favoured over the keto-amine tautomer.

An ORTEP view of the molecule is shown in Fig. 1. There are two independent molecules in the asymmetric unit which have very similar geometrical parameters. Both molecules adopt the phenol-imine tautomeric form and have a strong intramolecular O—H···N hydrogen bond whose details are given in Table 1. The C7—N1 [1.296 (4) Å] and C22—N2 [1.296 (4) Å] bond distances are of double-bond character, whereas, the C2—O1 [1.344 (4) Å] and C17—O4 [1.342 (4) Å] distances are single bonds. These distances are similar to other values reported in the literature [1.2889 (15) and 1.2891 (14) Å for C=N and 1.3486 (16) and 1.3443 (15) Å for C—O, respectively; Petek et al. (2007)]. Both molecules are not planar; the dihedral angle between the aromatic rings are 24.6 (2) and 30.30 (13) °, respectively.

Experimental

2-(4-Bromophenylimino)methyl-3,5-dimethoxyphenol was prepared by reflux a mixture of a solution containing 2-hydroxy-4, 6-dimethoxybenzaldehyde (0.02 g 0.11 mmol) in 20 ml ethanol and a solution containing 4-bromoaniline (0.019 g 0.11 mmol) in 20 ml ethanol. The reaction mixture was stirred for 1 hunder reflux. Crystals of 2-(4-Bromophenylimino)methyl-3,5-dimethoxyphenol suitable for X-ray analysis were obtained from ethylalcohol by slow evaporation (yield % 69; m.p.380–382 K).