(E)-4-Bromo-2-(2-methoxy­phenyl­imino­meth­yl)phenol

The mol­ecule of the title compound, C₁₄H₁₂BrNO₂, is almost planar and the dihedral angle between the planes of the two aromatic rings is 3.8 (2)°. The mol­ecule exists in the crystal structure in the phenol-imine tautomeric form, with the H atom located on O rather than on N. This H atom is involved in a strong intra­molecular hydrogen bond.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.032
• wR factor = 0.078
• Data-to-parameter ratio = 15.2

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT063_ALERT_3_C Crystal Probably too Large for Beam Size .......       0.80 mm

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

---

S1. Comment

Schiff bases have been extensively used as ligands in the field of coordination chemistry (Calligaris et al., 1972). There are two characteristic properties of Schiff bases, viz. photochromism and thermochromism (Cohen et al., 1964). These properties result from proton transfer from the hydroxyl O atom to the imine N atom (Hadjoudis et al., 1987). Schiff bases display two possible tautomeric forms, namely the phenol–imine and keto–amine forms. In the solid state, the keto–amine tautomer has been found in naphthaldimine (Hökelek et al., 2000). Nevertheless, in the solid state, it has been established that there is keto–amine tautomerism in naphthaldimine, while the phenol–imine form exists in salicylaldimine Schiff bases (Dey et al., 2001). Our investigations show that compound (I) adopts the phenol–imine tautomeric form. An ORTEP-3 (Farrugia, 1997) plot of the molecule of (I) is shown in Fig. 1. The C8—N1 and C1—C7 bond lengths are 1.413 (3) and 1.453 (3) Å, respectively (Table 1), and agree with the corresponding distances in (E)-2-Methoxy-6-[(2-trifluoromethylphenylimino)methyl]phenol [1.418 (5) and 1.454 (5) Å; Şahin et al., 2005]. The N1═C7 bond length of 1.274 (3) Å is typical of a double bond, similar to the corresponding bond length in N-[3,5-Bis(trifluoromethyl)phenyl]salicylaldimine [1.276 (4) Å; Karadayı et al., 2003]. The O2—C4 distance of 1.338 (3) Å is close to the value of 1.349 (6) Å in 3-tert-butyl-2-hydroxy-5-methoxyazobenzene (Işık et al., 1998).

Fig. 1 also shows a strong intramolecular hydrogen bond (O2—H2···N1) can be described as an S(6) motif (Bernstein et al., 1995). The O1—N1 distance of 2.575 (3) Å is comparable to those observed for analogous hydrogen bonds in (E)-2-[4-(Dimethylamino)phenyliminomethyl]-6-methylphenol [2.574 (3) Å; Gül et al., 2007].

Related literature

Schiff base compounds can be classified by their photochromic and thermochromic characteristics (Cohen et al., 1964; Hadjoudis et al., 1987). For other relevant literature, see: Bernstein et al. (1995); Calligaris et al. (1972); Dey et al. (2001); Farrugia (1999); Gül et al. (2007); Hökelek et al. (2000); Işık et al. (1998); Karadayı et al. (2003); Şahin et al. (2005).

S2. Experimental

The compound (E)-2-[(2-Methoxyphenylimino)methyl]-4-bromophenol was prepared by reflux a mixture of a solution containing 5-bromosalicylaldehyde (0.05 g 0.25 mmol) in 20 ml e thanol and a solution containing o-Anisidine (0.03 g 0.37 mmol) in 20 ml e thanol. The reaction mixture was stirred for 1 h under reflux. The crystals of (E)-2-[(2-Methoxyphenylimino)methyl]-4-bromophenol suitable for X-ray analysis were obtained from ethylalcohol by slow evaporation (yield % 70; m.p. 385–387 K).

S3. Refinement

The H2 atom was located in a difference map and refined freely (distances given in Table 2). All other H atoms were placed in calculated positions and constrained to ride on their parents atoms, with C—H = 0.93–0.96 Å and U_iso(H) = 1.2U_eq(C) or 1.5U_eq(C).

Computing details

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, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

Fig. 1. The molecular structure of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 40% probability.

(E)-4-Bromo-2-(2-methoxyphenyliminomethyl)phenol

Crystal data

C14H12BrNO2	F(000) = 1232
Mr = 306.16	Dx = 1.613 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 12164 reflections
a = 32.926 (3) Å	θ = 2.4–29.5°
b = 4.5564 (2) Å	µ = 3.25 mm^−1
c = 17.7214 (16) Å	T = 296 K
β = 108.465 (7)°	Prism, brown
V = 2521.8 (4) Å^3	0.80 × 0.38 × 0.08 mm
Z = 8

Data collection

Stoe IPDS II diffractometer	2480 independent reflections
Radiation source: fine-focus sealed tube	1712 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.052
Detector resolution: 6.67 pixels mm^-1	θmax = 26.0°, θmin = 2.4°
ω scans	h = −40→40
Absorption correction: integration (X-RED32; Stoe & Cie, 2002)	k = −5→5
Tmin = 0.221, Tmax = 0.712	l = −21→21
12218 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.032	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.078	H-atom parameters constrained
S = 0.98	w = 1/[σ^2(Fo^2) + (0.0418P)^2] where P = (Fo^2 + 2Fc^2)/3
2480 reflections	(Δ/σ)max < 0.001
163 parameters	Δρmax = 0.26 e Å^−3
0 restraints	Δρmin = −0.46 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Br1	0.234247 (8)	−0.00729 (8)	0.138938 (19)	0.06755 (13)
O2	0.41248 (5)	0.4833 (4)	0.22498 (11)	0.0609 (5)
H2	0.4147	0.5989	0.1910	0.091*
N1	0.38806 (6)	0.7855 (4)	0.09558 (12)	0.0442 (5)
C1	0.29059 (8)	0.1497 (6)	0.16474 (16)	0.0456 (6)
C8	0.39867 (7)	0.9886 (6)	0.04460 (14)	0.0421 (5)
C9	0.37013 (8)	1.1040 (6)	−0.02393 (16)	0.0492 (6)
H9	0.3415	1.0472	−0.0391	0.059*
O1	0.46804 (6)	0.9510 (5)	0.13433 (11)	0.0636 (6)
C3	0.34117 (7)	0.4621 (5)	0.13301 (14)	0.0401 (5)
C4	0.37255 (7)	0.3770 (6)	0.20377 (15)	0.0440 (6)
C10	0.38344 (9)	1.3026 (6)	−0.07027 (16)	0.0533 (7)
H10	0.3640	1.3775	−0.1165	0.064*
C2	0.30006 (7)	0.3460 (6)	0.11415 (15)	0.0453 (6)
H22	0.2791	0.4014	0.0674	0.054*
C7	0.35084 (8)	0.6732 (6)	0.07962 (15)	0.0453 (6)
H7	0.3296	0.7271	0.0331	0.054*
C5	0.36185 (8)	0.1758 (6)	0.25349 (16)	0.0519 (7)
H5	0.3825	0.1166	0.3003	0.062*
C13	0.44153 (8)	1.0756 (6)	0.06709 (16)	0.0492 (7)
C6	0.32113 (9)	0.0640 (6)	0.23411 (16)	0.0506 (7)
H6	0.3142	−0.0694	0.2678	0.061*
C12	0.45450 (9)	1.2780 (7)	0.02073 (18)	0.0646 (8)
H12	0.4829	1.3394	0.0359	0.078*
C11	0.42538 (10)	1.3882 (7)	−0.04772 (18)	0.0621 (8)
H11	0.4344	1.5219	−0.0788	0.075*
C14	0.51133 (9)	1.0510 (9)	0.1620 (2)	0.0876 (12)
H14A	0.5266	0.9471	0.2097	0.131*
H14B	0.5118	1.2574	0.1731	0.131*
H14C	0.5247	1.0156	0.1220	0.131*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.04646 (16)	0.0750 (2)	0.0816 (2)	−0.01226 (15)	0.02084 (14)	0.0042 (2)
O2	0.0431 (9)	0.0699 (12)	0.0585 (11)	−0.0084 (10)	−0.0001 (8)	0.0139 (11)
N1	0.0433 (11)	0.0431 (12)	0.0450 (12)	−0.0022 (9)	0.0125 (9)	0.0001 (10)
C1	0.0409 (12)	0.0454 (14)	0.0517 (15)	−0.0011 (11)	0.0161 (12)	−0.0004 (13)
C8	0.0450 (12)	0.0389 (12)	0.0427 (12)	−0.0022 (12)	0.0145 (10)	−0.0045 (14)
C9	0.0462 (14)	0.0480 (14)	0.0496 (15)	−0.0037 (11)	0.0098 (12)	−0.0006 (12)
O1	0.0456 (10)	0.0797 (15)	0.0555 (11)	−0.0110 (10)	0.0019 (8)	0.0151 (11)
C3	0.0400 (11)	0.0388 (14)	0.0403 (12)	0.0008 (10)	0.0113 (10)	−0.0036 (12)
C4	0.0378 (13)	0.0453 (13)	0.0456 (14)	0.0021 (10)	0.0083 (11)	−0.0022 (12)
C10	0.0612 (16)	0.0525 (17)	0.0435 (15)	0.0005 (13)	0.0126 (13)	0.0031 (13)
C2	0.0401 (13)	0.0468 (14)	0.0452 (14)	0.0002 (11)	0.0082 (11)	0.0006 (12)
C7	0.0456 (14)	0.0432 (15)	0.0436 (14)	0.0018 (11)	0.0093 (11)	−0.0006 (12)
C5	0.0508 (15)	0.0559 (17)	0.0444 (15)	0.0025 (12)	0.0084 (12)	0.0086 (14)
C13	0.0453 (14)	0.0537 (17)	0.0458 (15)	−0.0038 (11)	0.0105 (12)	−0.0015 (12)
C6	0.0556 (15)	0.0505 (18)	0.0490 (15)	−0.0009 (12)	0.0211 (12)	0.0056 (12)
C12	0.0513 (16)	0.078 (2)	0.0624 (19)	−0.0161 (15)	0.0152 (14)	0.0107 (17)
C11	0.0629 (18)	0.0669 (18)	0.0599 (18)	−0.0091 (15)	0.0241 (15)	0.0138 (15)
C14	0.0432 (15)	0.137 (4)	0.072 (2)	−0.0155 (19)	0.0029 (14)	0.022 (2)

Geometric parameters (Å, º)

Br1—C1	1.904 (2)	C4—C5	1.392 (4)
O2—C4	1.338 (3)	C10—C11	1.367 (4)
O2—H2	0.8200	C10—H10	0.9300
N1—C7	1.274 (3)	C2—H22	0.9300
N1—C8	1.413 (3)	C7—H7	0.9300
C1—C2	1.370 (4)	C5—C6	1.372 (4)
C1—C6	1.376 (4)	C5—H5	0.9300
C8—C9	1.382 (4)	C13—C12	1.389 (4)
C8—C13	1.397 (3)	C6—H6	0.9300
C9—C10	1.383 (4)	C12—C11	1.381 (4)
C9—H9	0.9300	C12—H12	0.9300
O1—C13	1.358 (3)	C11—H11	0.9300
O1—C14	1.427 (3)	C14—H14A	0.9600
C3—C2	1.392 (3)	C14—H14B	0.9600
C3—C4	1.404 (3)	C14—H14C	0.9600
C3—C7	1.453 (3)
C4—O2—H2	109.5	N1—C7—C3	121.0 (2)
C7—N1—C8	122.4 (2)	N1—C7—H7	119.5
C2—C1—C6	121.1 (2)	C3—C7—H7	119.5
C2—C1—Br1	119.63 (19)	C6—C5—C4	120.6 (2)
C6—C1—Br1	119.26 (19)	C6—C5—H5	119.7
C9—C8—C13	119.1 (2)	C4—C5—H5	119.7
C9—C8—N1	125.0 (2)	O1—C13—C12	124.3 (2)
C13—C8—N1	115.8 (2)	O1—C13—C8	116.2 (2)
C8—C9—C10	121.0 (2)	C12—C13—C8	119.4 (3)
C8—C9—H9	119.5	C5—C6—C1	119.9 (2)
C10—C9—H9	119.5	C5—C6—H6	120.1
C13—O1—C14	117.6 (2)	C1—C6—H6	120.1
C2—C3—C4	119.6 (2)	C11—C12—C13	120.2 (3)
C2—C3—C7	119.5 (2)	C11—C12—H12	119.9
C4—C3—C7	120.9 (2)	C13—C12—H12	119.9
O2—C4—C5	118.9 (2)	C10—C11—C12	120.6 (3)
O2—C4—C3	122.1 (2)	C10—C11—H11	119.7
C5—C4—C3	119.0 (2)	C12—C11—H11	119.7
C11—C10—C9	119.6 (3)	O1—C14—H14A	109.5
C11—C10—H10	120.2	O1—C14—H14B	109.5
C9—C10—H10	120.2	H14A—C14—H14B	109.5
C1—C2—C3	119.8 (2)	O1—C14—H14C	109.5
C1—C2—H22	120.1	H14A—C14—H14C	109.5
C3—C2—H22	120.1	H14B—C14—H14C	109.5
C7—N1—C8—C9	4.9 (4)	O2—C4—C5—C6	179.4 (3)
C7—N1—C8—C13	−175.3 (2)	C3—C4—C5—C6	−0.6 (4)
C13—C8—C9—C10	0.1 (4)	C14—O1—C13—C12	4.7 (4)
N1—C8—C9—C10	179.9 (2)	C14—O1—C13—C8	−175.6 (3)
C2—C3—C4—O2	−179.6 (2)	C9—C8—C13—O1	−179.1 (2)
C7—C3—C4—O2	−0.4 (4)	N1—C8—C13—O1	1.1 (3)
C2—C3—C4—C5	0.4 (4)	C9—C8—C13—C12	0.7 (4)
C7—C3—C4—C5	179.6 (2)	N1—C8—C13—C12	−179.1 (2)
C8—C9—C10—C11	−0.5 (4)	C4—C5—C6—C1	0.4 (4)
C6—C1—C2—C3	−0.2 (4)	C2—C1—C6—C5	0.0 (4)
Br1—C1—C2—C3	179.73 (19)	Br1—C1—C6—C5	−179.9 (2)
C4—C3—C2—C1	0.0 (4)	O1—C13—C12—C11	178.6 (3)
C7—C3—C2—C1	−179.2 (2)	C8—C13—C12—C11	−1.1 (4)
C8—N1—C7—C3	179.3 (2)	C9—C10—C11—C12	0.1 (5)
C2—C3—C7—N1	179.3 (2)	C13—C12—C11—C10	0.7 (5)
C4—C3—C7—N1	0.2 (4)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···N1	0.82	1.85	2.575 (3)	147