3-Bromo-2-hy­dr­oxy­benzaldehyde

The mol­ecule of the title compound, C₇H₅BrO₂, is almost planar (r.m.s. deviation from the plane of all the non-H atoms = 0.0271 Å) and displays intra­molecular O—H⋯O hydrogen bonding between the phenol group and the aldehyde O atom. Packing is directed by weak inter­molecular C—H⋯Br inter­actions and π-stacking between nearly parallel mol­ecules [dihedral angle = 5.30 (6)° and centroid–centroid distance = 3.752 (1) Å].

Related literature

For information on the synthesis of the title compound, see: Hansen & Skattebol (2005). For recent uses of the title compound in the synthesis of biologically active compounds, see: Velázquez et al. (2012); Wang et al. (2012); Zhang et al. (2012). For use of the title compound to prepare Schiff base ligands for metal coordination chemistry, see: Escudero-Adán et al. (2010); McGarrigle et al. (2004); Tzubery & Tshuva (2012). For related crystal structures, see: Balasubramani et al. (2011); Fan, You, Liu, Qian & Huang (2008); Fan, You, Qian, Liu & Huang (2008) Iwasaki et al. (1976); Kirchner et al. (2011); Tang et al. (2010).

Experimental

Crystal data

• C₇H₅BrO₂

• M_r = 201.02

• Monoclinic, P 2₁ /c

• a = 7.0282 (3) Å

• b = 14.9715 (7) Å

• c = 6.8472 (3) Å

• β = 108.907 (1)°

• V = 681.61 (5) ų

• Z = 4

• Mo Kα radiation

• μ = 5.96 mm⁻¹

• T = 125 K

• 0.22 × 0.08 × 0.03 mm

Data collection

• Bruker APEXII CCD diffractometer

• Absorption correction: multi-scan (SADABS; Bruker 2007) T_min = 0.354, T_max = 0.842

• 10788 measured reflections

• 2074 independent reflections

• 1815 reflections with I > 2σ(I)

• R_int = 0.024

Refinement

• R[F² > 2σ(F²)] = 0.019

• wR(F²) = 0.048

• S = 1.04

• 2074 reflections

• 95 parameters

• H atoms treated by a mixture of independent and constrained refinement

• Δρ_max = 0.46 e Å⁻³

• Δρ_min = −0.25 e Å⁻³

Table 1
Hydrogen-bond and C—H⋯Br interaction geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2⋯O1	0.79 (2)	1.90 (2)	2.6364 (16)	154 (2)
C4—H4⋯Br1^i	0.95	3.05	3.798 (2)	137
Symmetry code: (i) x+1, y, z.

Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL and OLEX2 (Dolomanov et al., 2009).

Supporting information

S1. Comment

The title compound, 3-bromo-2-hydroxybenzaldehyde, may be synthesized by reflux of 2-bromophenol with anhydrous magnesium dichloride, solid paraformaldehyde, and triethylamine in dry tetrahydrofuran (Hansen & Skattebol, 2005). Salicylaldehyde and its derivatives are commonly employed in the formation of Schiff bases for use as ligands in metal coordination chemistry. Schiff base complexes derived from 3-bromo-2-hydroxybenzaldehyde have been reported for several metals, including titanium (Tzubery & Tshuva, 2012), zinc (Escudero-Adán et al., 2010) and chromium (McGarrigle et al., 2004). 3-Bromo-2-hydroxybenzaldehyde is used as a synthetic reagent in the synthesis of biologically active compounds such as potential antiviral compounds (Velázquez et al., 2012), chiral aromatic spiroketals (Wang et al., 2012), and anticancer agents (Zhang et al., 2012).

The structure of the title compound (Fig. 1) shows that the molecule is planar, with a root mean square deviation from the plane of all atoms, excluding the aryl H atoms, of 0.0271 Å. The phenol is intramolecularly hydrogen bonded to the aldehyde group meta to it on the aryl ring, with an O···O distance of 2.6364 (16) Å and O—H···O angle of 154 (2)°. This intramolecular hydrogen bond is common to salicylaldehyde derivatives, having metrical parameters comparable to related structures (viz., 3,5-dibromo-2-hydroxybenzaldehyde (Fan, You, Qian, Liu & Huang, 2008); 3,5-dichloro-2-hydroxybenzaldehyde (Fan, You, Liu, Qian & Huang, 2008); 3-bromo-5-tert-butyl-2 -hydroxybenzaldehyde (Balasubramani et al., 2011); 2-hydroxy-3-methoxybenzaldehyde (Iwasaki et al., 1976); 2-hydroxy-3-nitrobenzaldehyde (Tang et al., 2010); hydroxybenzaldehyde (Kirchner et al., 2011). While O···O distances are rather similar in these structures (range: 2.597 (3)-2.713 (6)Å; Δ: 5%), O—H···O angles are slightly more uneven (range: 143 (2)-163 (2)Å, Δ: 13%) depending on the nature of intermolecular interactions involving the phenol and aldehyde substituents on neighbouring molecules.

Inspection of the molecular packing reveals that the crystal structure is organized by weak intermolecular C-H···Br interactions, with an H···Br distance of 3.05 Å and C—H···Br angle of 136.74°. There also exists an offset face-to-face π-stacking chain of molecues running parallel to the crystallographic c-axis, with an angle between the planes of the overlapping molecules of 5.30 (6)°. This π-stacking is characterized by a centroid-to-centroid distance of 3.752 (1) Å and centroid-to-plance distances of 3.346 (1) and 3.488 (1), resulting in a ring-offsets of 1.381 (2) and 1.697 (2) Å, respectively (Fig 2).

Related literature

For information on the synthesis of the title compound, see: Hansen & Skattebol (2005). For recent uses of the title compound in the synthesis of biologically active compounds, see: Velázquez et al. (2012); Wang et al. (2012); Zhang et al. (2012). For use of the title compound to prepare Schiff base ligands for metal coordination chemistry, see: Escudero-Adán et al. (2010); McGarrigle et al. (2004); Tzubery & Tshuva (2012). For related crystal structures, see: Balasubramani et al. (2011); Fan, You, Liu, Qian & Huang (2008); Fan, You, Qian, Liu & Huang (2008) Iwasaki et al. (1976); Kirchner et al. (2011); Tang et al. (2010).

S2. Experimental

Crystalline 3-bromo-2-hydroxybenzaldehyde was purchased from Aldrich Chemical Company, USA.

S3. Refinement

All non-hydrogen atoms were refined anisotropically. Hydrogen atoms on carbon were included in calculated positions and refined using a riding model at C–H = 0.95 Å and U_iso(H) = 1.2 × U_eq(C) of the aryl C-atoms. The hydrogen atom on oxygen was located in the difference map and refined freely. The extinction parameter (EXTI) refined to zero and was removed from the refinement.

Computing details

Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and OLEX2 (Dolomanov et al., 2009).

Figures

	Fig. 1. A view of the title compound with the atom numbering scheme. Displacement ellipsoids are shown at the 50% probability level.
	Fig. 2. A view of the offset face-to-face π-stacking in the structure of the title compound (See text for details)

3-Bromo-2-hydroxybenzaldehyde

Crystal data

C7H5BrO2	F(000) = 392
Mr = 201.02	Dx = 1.959 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 6585 reflections
a = 7.0282 (3) Å	θ = 2.7–30.5°
b = 14.9715 (7) Å	µ = 5.96 mm^−1
c = 6.8472 (3) Å	T = 125 K
β = 108.907 (1)°	Plate, colourless
V = 681.61 (5) Å^3	0.22 × 0.08 × 0.03 mm
Z = 4

Data collection

Bruker APEXII CCD diffractometer	2074 independent reflections
Radiation source: fine-focus sealed tube	1815 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.024
φ and ω scans	θmax = 30.5°, θmin = 2.7°
Absorption correction: multi-scan (SADABS; Bruker 2007)	h = −10→10
Tmin = 0.354, Tmax = 0.842	k = −21→21
10788 measured reflections	l = −9→9

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)] = 0.019	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.048	H atoms treated by a mixture of independent and constrained refinement
S = 1.04	w = 1/[σ^2(Fo^2) + (0.0249P)^2 + 0.1779P] where P = (Fo^2 + 2Fc^2)/3
2074 reflections	(Δ/σ)max = 0.001
95 parameters	Δρmax = 0.46 e Å^−3
0 restraints	Δρmin = −0.25 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	0.11374 (2)	0.567091 (9)	0.25208 (2)	0.02342 (6)
O2	0.12613 (15)	0.76969 (8)	0.28306 (17)	0.0236 (2)
H2	0.144 (4)	0.8217 (17)	0.294 (4)	0.055 (8)*
C1	0.4646 (2)	0.88799 (9)	0.3840 (2)	0.0228 (3)
H1	0.5839	0.9229	0.4229	0.027*
O1	0.30259 (19)	0.92736 (7)	0.33528 (18)	0.0284 (2)
C6	0.3410 (2)	0.64329 (9)	0.3299 (2)	0.0170 (2)
C7	0.3132 (2)	0.73579 (9)	0.3323 (2)	0.0166 (2)
C3	0.6776 (2)	0.75351 (10)	0.4401 (2)	0.0202 (3)
H3	0.7925	0.7913	0.4781	0.024*
C5	0.5322 (2)	0.60728 (9)	0.3814 (2)	0.0192 (3)
H5	0.5480	0.5443	0.3776	0.023*
C2	0.4853 (2)	0.79087 (9)	0.38599 (19)	0.0177 (2)
C4	0.7016 (2)	0.66178 (10)	0.4385 (2)	0.0219 (3)
H4	0.8323	0.6363	0.4760	0.026*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.01950 (8)	0.01875 (8)	0.03050 (9)	−0.00399 (5)	0.00602 (6)	−0.00323 (5)
O2	0.0177 (5)	0.0199 (5)	0.0302 (6)	0.0043 (4)	0.0037 (4)	−0.0004 (4)
C1	0.0317 (8)	0.0177 (6)	0.0188 (6)	−0.0035 (6)	0.0080 (6)	0.0005 (5)
O1	0.0383 (7)	0.0187 (5)	0.0275 (6)	0.0039 (4)	0.0095 (5)	0.0031 (4)
C6	0.0183 (6)	0.0165 (6)	0.0158 (6)	−0.0017 (5)	0.0049 (5)	−0.0020 (5)
C7	0.0168 (6)	0.0177 (6)	0.0144 (6)	0.0022 (5)	0.0040 (5)	−0.0002 (5)
C3	0.0190 (7)	0.0241 (7)	0.0175 (6)	−0.0041 (5)	0.0059 (5)	−0.0014 (5)
C5	0.0222 (7)	0.0172 (6)	0.0181 (6)	0.0027 (5)	0.0062 (5)	−0.0014 (5)
C2	0.0222 (6)	0.0169 (6)	0.0134 (6)	−0.0018 (5)	0.0050 (5)	−0.0005 (5)
C4	0.0174 (6)	0.0265 (7)	0.0208 (6)	0.0037 (5)	0.0048 (5)	−0.0009 (5)

Geometric parameters (Å, º)

Br1—C6	1.8933 (13)	C7—C2	1.4107 (19)
O2—C7	1.3466 (16)	C3—C4	1.384 (2)
O2—H2	0.79 (2)	C3—C2	1.397 (2)
C1—O1	1.2284 (19)	C3—H3	0.9500
C1—C2	1.4609 (19)	C5—C4	1.391 (2)
C1—H1	0.9500	C5—H5	0.9500
C6—C5	1.3836 (19)	C4—H4	0.9500
C6—C7	1.3993 (19)
C7—O2—H2	103.8 (18)	C4—C3—H3	119.8
O1—C1—C2	124.12 (14)	C2—C3—H3	119.8
O1—C1—H1	117.9	C6—C5—C4	121.02 (13)
C2—C1—H1	117.9	C6—C5—H5	119.5
C5—C6—C7	120.67 (13)	C4—C5—H5	119.5
C5—C6—Br1	119.87 (10)	C3—C2—C7	120.60 (13)
C7—C6—Br1	119.45 (10)	C3—C2—C1	119.08 (13)
O2—C7—C6	119.90 (12)	C7—C2—C1	120.32 (13)
O2—C7—C2	122.02 (12)	C3—C4—C5	119.28 (13)
C6—C7—C2	118.08 (12)	C3—C4—H4	120.4
C4—C3—C2	120.32 (13)	C5—C4—H4	120.4
C5—C6—C7—O2	−179.59 (12)	O2—C7—C2—C3	178.81 (12)
Br1—C6—C7—O2	1.18 (17)	C6—C7—C2—C3	−1.59 (19)
C5—C6—C7—C2	0.79 (19)	O2—C7—C2—C1	−1.71 (19)
Br1—C6—C7—C2	−178.43 (9)	C6—C7—C2—C1	177.89 (12)
C7—C6—C5—C4	0.6 (2)	O1—C1—C2—C3	178.64 (13)
Br1—C6—C5—C4	179.81 (11)	O1—C1—C2—C7	−0.9 (2)
C4—C3—C2—C7	1.0 (2)	C2—C3—C4—C5	0.4 (2)
C4—C3—C2—C1	−178.47 (13)	C6—C5—C4—C3	−1.2 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···O1	0.79 (2)	1.90 (2)	2.6364 (16)	154 (2)
C4—H4···Br1^i	0.95	3.05	3.798 (2)	137

Symmetry code: (i) x+1, y, z.