Buy article online - an online subscription or single-article purchase is required to access this article.
Download citation
Download citation
link to html
The mol­ecules of the title compound, C7H5BrO2, form zigzag chains running along the b axis and are stacked in layers perpendicular to the a axis. Intermolecular bonding occurs through hydrogen bonds linking the hydroxyl and carbonyl groups, with an O...O distance of 2.804 (4) Å. The Br atom deviates significantly from the plane of the ring and the aldehyde group is twisted by 7.1 (5)° around the Csp2-Caryl bond. The geometry of the mol­ecule in the crystal is compared to that given by ab initio quantum mechanical calculations for the isolated mol­ecule, using a molecular orbital Hartree-Fock method and density functional theory.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270199015267/sk1352sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270199015267/sk1352Isup2.hkl
Contains datablock I

CCDC reference: 143256

Comment top

We have recently reported the structures of 2,4-dibromo and 2,4,6-tribromo derivatives of m-hydroxybenzaldehyde (Matos Beja, Paixão, Ramos Silva, Alte da Veiga et al., 1997; Matos Beja, Paixão, Ramos Silva, d'A. Rocha Gonsalves et al., 1997), compounds which we came across as precursors for the synthesis of meso-tetraaryl-substituted porphyrins. We report here the synthesis and the crystal structure of the monobromoderivative of m-hydroxybenzaldehyde.

Hodgson & Beard (1925) mention that monobromination of m-hydroxybenzaldehyde in chloroform occurs at positions 2 and 4 and isolated the 2-bromoderivative. Pandya et al. (1952) carried out the bromination in acetic acid and isolated a product with a very similar melting point to that obtained by Hodgson & Beard and identified it as the 4-bromoderivative. In order to clarify which isomer is obtained by monobromination of m-hydroxybenzaldehyde we followed Pandya's conditions and Hodgson & Beard's and have isolated the same compound in both conditions. This was identified by X-ray diffraction as the title compound, the 2-bromo-5-hydroxybenzaldehyde isomer, (I). \sch

The internal bond angles of the ring at C1 [118.3 (3)°] and C2 [121.1 (3)°] deviate significantly from the ideal value of 120°. While the hydroxyl O2 atom is coplanar with the benzene ring within experimental uncertainty both the aldehyde group and the Br atom are tilted out from this plane. The deviations from the least-squares benzene ring plane are Br 0.032 (5), C7 - 0.042 (5), O1 - 0.181 (6) Å. The C7—C1 bond is slightly tilted out of the ring plane and there is also a pronounced in-plane twist as shown by the large asymmetry between C6—C1—C7 [117.4 (3)°] and C2—C1—C7 [124.3 (3)°] bond angles. In addition, the aldehyde group is rotated by 7.1 (5)° around the C1—C7 bond. These effects may be due to a steric interaction between the formyl-H atom and the bulky Br atom but may also reflect to some extent the involvement of the aldehyde group in intermolecular hydrogen-bond interactions. In order to distinguish between these two effects, we have performed an optimization of the geometry of the isolated molecule by ab initio quantum mechanical Molecular Orbital Hartree-Fock (MO—HF) calculations using the computer code GAMESS (Schmidt et al., 1993). The atomic wavefunctions of the light atoms were expanded on a standard 6–31 G(d,p) basis set and for the Br atom the 'double zeta' basis set of Binning & Curtiss (1990) was used. The optimization was conducted starting from the experimental X-ray geometry without imposing any symmetry constraint on the molecule. Each self-consistent field calculation was iterated until a Δρ of less than 10-5 bohr-3 was achieved. The final equilibrium geometry at the minimum energy had a maximum gradient in internal coordinates of 10-5 hartree bohr-1 or 10-5 hartree rad-1. A similar geometry optimization was also performed using a density functional theory (DFT) hamiltonian, with similar results to the Hartree-Fock calculation. The DFT calculations were performed with the computer code DeFT2.2 (St-Amant et al., 1998) employing a VWC exchange-correlation potential (Vosko et al., 1980). Both methods reproduce well the in-plane twist of the C1–C7 bond [calculated values: C2–C1–C7 DFT 123.53°; MO—HF 123.55°, C6–C1–C7 DFT \& MO—HF 117.38°]. However, the minimum energy of the molecule occurs for a geometry close to Cs symmetry where all the substituent atoms are practically within the ring plane. We conclude that the observed twist of the aldehyde group around the C1–C7 bond is due to the intermolecular interaction between the aldehyde and hydroxyl groups.

The molecules are stacked in layers perpendicular to the short a axis. The hydroxyl and carbonyl group interact via a hydrogen bond [O2···O1 2.804 (4) Å] forming zigzag chains running along the b axis. Similar chains were found in the crystal structure of 2,4,6-tribromoderivative in contrast with the situation found in the 2,4-dibromo derivative where the hydrogen bonds join pairs of molecules in dimers across a centre of symmetry. Judging by the O—H···O bond distances and angles, it appears that the strongest hydrogen bonds occur in the monobromoderivative.

Experimental top

The title compound was prepared by slowly adding bromine (0.87 cm3) to a solution of 3-hydroxybenzaldehyde (2.0 g) in glacial acetic acid (10 cm3). After 3 h, water was added to precipitate a solid and the mixture was left overnight in the refrigerator. The solid was filtered and recrystallized in water to give 2.25 g of the title compound [η = 68%; m.p. 405–406 K, literature 406 K (Pandya et al., 1952)]. MS (EI) 201 (M+). 1H NMR (300 MHz, CDCl3/DMSO-d6, p.p.m.): δ 10.1 (s, 1H, CHO), 9.7 (s, 1H, OH), 7.4 (d, 1H, J = 8.7 Hz, CH-aryl), 7.2 (d, 1H, J = 3.0 Hz, CH-aryl), 6.9 (dd, 1H, J = 8.7 and 3.0 Hz, CH-aryl); 13C NMR (75.5 MHz, CDCl3/DMSO-d6, p.p.m.): 191.4, 157.1, 134.0, 133.3, 123.1, 115.3, 114.9; IR (KBr) cm-1 3331(m) (OH), 1684 (s,CO), 1595, 1480 (s, CC aromatic), 1305(s), 1236(s), 1170 (m, C–O), 866 (m), 831(m), 763(m), 586(m) elemental analysis calculated for C7H5O2Br: C 41.8, H 2.5%; found C 41.6, H 2.4%.

Refinement top

The H atoms of the organic moiety were placed at calculated positions and refined as riding using the SHELXL97 defaults: O–H = 0.82 Å, C—H = 0.93 Å and U(H) = 1.2Ueq(C parent atom), U(H) = 1.5Ueq(O parent atom). Examination of the crystal structure with PLATON (Spek, 1995) showed that there are no solvent-accessible voids in the crystal lattice. All calculations were performed on a PentiumII 330 MHz PC running LINUX.

Computing details top

Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software; data reduction: HELENA (Spek, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. ORTEPII (Johnson, 1976) plot of the title compound. Displacement ellipsoids are drawn at the 50% level.
[Figure 2] Fig. 2. Projection of the crystal structure on the bc plane showing the hydrogen-bonding chains running along the b axis.
2-bromo-5-hydroxybenzaldehyde top
Crystal data top
C7H5BrO2Dx = 1.912 Mg m3
Mr = 201.01Melting point: 405(1) K
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
a = 3.974 (3) ÅCell parameters from 25 reflections
b = 9.164 (8) Åθ = 8.5–17.1°
c = 19.172 (6) ŵ = 5.81 mm1
V = 698.2 (8) Å3T = 293 K
Z = 4Block, light yellow
F(000) = 3920.38 × 0.32 × 0.32 mm
Data collection top
Enraf-Nonius CAD-4
diffractometer
925 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.035
Graphite monochromatorθmax = 25.0°, θmin = 3.1°
profile data from ω–2θ scansh = 04
Absorption correction: ψ scan
(North et al., 1968)
k = 1010
Tmin = 0.126, Tmax = 0.156l = 2222
2879 measured reflections3 standard reflections every 180 min
1225 independent reflections intensity decay: 8.5%
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)] = 0.023H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.051 w = 1/[σ2(Fo2) + (0.023P)2 + 0.1029P]
where P = (Fo2 + 2Fc2)/3
S = 1.05(Δ/σ)max = 0.001
1225 reflectionsΔρmax = 0.38 e Å3
92 parametersΔρmin = 0.27 e Å3
0 restraintsAbsolute structure: Flack (1983)
Primary atom site location: structure-invariant direct methodsAbsolute structure parameter: 0.014 (17)
Crystal data top
C7H5BrO2V = 698.2 (8) Å3
Mr = 201.01Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 3.974 (3) ŵ = 5.81 mm1
b = 9.164 (8) ÅT = 293 K
c = 19.172 (6) Å0.38 × 0.32 × 0.32 mm
Data collection top
Enraf-Nonius CAD-4
diffractometer
925 reflections with I > 2σ(I)
Absorption correction: ψ scan
(North et al., 1968)
Rint = 0.035
Tmin = 0.126, Tmax = 0.1563 standard reflections every 180 min
2879 measured reflections intensity decay: 8.5%
1225 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.023H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.051Δρmax = 0.38 e Å3
S = 1.05Δρmin = 0.27 e Å3
1225 reflectionsAbsolute structure: Flack (1983)
92 parametersAbsolute structure parameter: 0.014 (17)
0 restraints
Special details top

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. The structure was solved by direct methods using SHELXS97.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Br0.13537 (10)0.63600 (4)0.11874 (2)0.05706 (14)
O10.4577 (7)0.8721 (3)0.27615 (12)0.0566 (7)
O20.2227 (9)1.2735 (2)0.10229 (12)0.0585 (8)
H20.30361.30320.13900.088*
C10.1626 (9)0.8998 (3)0.17039 (15)0.0340 (7)
C20.0121 (8)0.8364 (3)0.1155 (2)0.0399 (8)
C30.1044 (10)0.9167 (4)0.05813 (17)0.0445 (8)
H30.22110.87240.02180.053*
C40.0246 (10)1.0624 (4)0.0543 (2)0.0472 (10)
H40.08741.11660.01540.057*
C50.1494 (9)1.1287 (3)0.10838 (15)0.0413 (7)
C60.2411 (9)1.0487 (3)0.16615 (18)0.0392 (9)
H60.35581.09370.20260.047*
C70.2779 (9)0.8206 (3)0.23225 (19)0.0435 (9)
H70.20760.72450.23790.052*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Br0.0556 (2)0.04707 (19)0.0685 (2)0.0137 (2)0.0018 (3)0.0053 (2)
O10.0767 (18)0.0522 (14)0.0408 (13)0.0061 (16)0.0174 (14)0.0004 (14)
O20.090 (2)0.0397 (13)0.0453 (15)0.0027 (13)0.0082 (15)0.0079 (11)
C10.0307 (18)0.0394 (16)0.0318 (17)0.0009 (18)0.0052 (18)0.0010 (13)
C20.0336 (15)0.0414 (17)0.045 (2)0.0019 (13)0.0074 (18)0.0009 (19)
C30.043 (2)0.0556 (18)0.0345 (19)0.005 (2)0.001 (2)0.0081 (16)
C40.050 (2)0.057 (2)0.035 (2)0.0068 (18)0.0030 (18)0.0024 (17)
C50.0470 (18)0.0420 (15)0.0350 (18)0.003 (2)0.004 (2)0.0053 (18)
C60.044 (2)0.0408 (18)0.033 (2)0.0007 (15)0.0007 (16)0.0003 (15)
C70.049 (2)0.0407 (18)0.041 (2)0.0030 (16)0.0000 (18)0.0030 (15)
Geometric parameters (Å, º) top
Br—C21.902 (3)C3—C41.374 (5)
O1—C71.201 (4)C3—H30.9300
O2—C51.364 (4)C4—C51.386 (5)
O2—H20.8200C4—H40.9300
C1—C21.388 (5)C5—C61.377 (4)
C1—C61.402 (4)C6—H60.9300
C1—C71.464 (5)C7—H70.9300
C2—C31.374 (5)
C5—O2—H2109.5C3—C4—H4120.0
C2—C1—C6118.3 (3)C5—C4—H4120.0
C2—C1—C7124.3 (3)O2—C5—C6122.0 (3)
C6—C1—C7117.4 (3)O2—C5—C4118.0 (3)
C3—C2—C1121.1 (3)C6—C5—C4120.0 (3)
C3—C2—Br118.3 (3)C5—C6—C1120.4 (3)
C1—C2—Br120.6 (3)C5—C6—H6119.8
C2—C3—C4120.1 (3)C1—C6—H6119.8
C2—C3—H3120.0O1—C7—C1124.0 (3)
C4—C3—H3120.0O1—C7—H7118.0
C3—C4—C5120.1 (3)C1—C7—H7118.0
C6—C1—C2—C30.5 (5)C3—C4—C5—C60.3 (6)
C7—C1—C2—C3178.2 (3)O2—C5—C6—C1179.7 (4)
C6—C1—C2—Br178.6 (2)C4—C5—C6—C10.7 (5)
C7—C1—C2—Br2.7 (5)C2—C1—C6—C50.7 (5)
C1—C2—C3—C40.1 (5)C7—C1—C6—C5178.0 (3)
Br—C2—C3—C4179.0 (3)C2—C1—C7—O1172.2 (4)
C2—C3—C4—C50.0 (6)C6—C1—C7—O16.5 (5)
C3—C4—C5—O2179.9 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H2···O1i0.821.992.804 (4)175
Symmetry code: (i) x1, y+1/2, z+1/2.

Experimental details

Crystal data
Chemical formulaC7H5BrO2
Mr201.01
Crystal system, space groupOrthorhombic, P212121
Temperature (K)293
a, b, c (Å)3.974 (3), 9.164 (8), 19.172 (6)
V3)698.2 (8)
Z4
Radiation typeMo Kα
µ (mm1)5.81
Crystal size (mm)0.38 × 0.32 × 0.32
Data collection
DiffractometerEnraf-Nonius CAD-4
diffractometer
Absorption correctionψ scan
(North et al., 1968)
Tmin, Tmax0.126, 0.156
No. of measured, independent and
observed [I > 2σ(I)] reflections
2879, 1225, 925
Rint0.035
(sin θ/λ)max1)0.594
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.023, 0.051, 1.05
No. of reflections1225
No. of parameters92
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.38, 0.27
Absolute structureFlack (1983)
Absolute structure parameter0.014 (17)

Computer programs: CAD-4 Software (Enraf-Nonius, 1989), CAD-4 Software, HELENA (Spek, 1997), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), ORTEPII (Johnson, 1976), SHELXL97.

Selected bond and torsion angles (º) top
C2—C1—C6118.3 (3)C3—C4—C5120.1 (3)
C3—C2—C1121.1 (3)C6—C5—C4120.0 (3)
C2—C3—C4120.1 (3)C5—C6—C1120.4 (3)
C2—C1—C7—O1172.2 (4)C6—C1—C7—O16.5 (5)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H2···O1i0.821.992.804 (4)174.6
Symmetry code: (i) x1, y+1/2, z+1/2.
 

Subscribe to Acta Crystallographica Section C: Structural Chemistry

The full text of this article is available to subscribers to the journal.

If you have already registered and are using a computer listed in your registration details, please email support@iucr.org for assistance.

Buy online

You may purchase this article in PDF and/or HTML formats. For purchasers in the European Community who do not have a VAT number, VAT will be added at the local rate. Payments to the IUCr are handled by WorldPay, who will accept payment by credit card in several currencies. To purchase the article, please complete the form below (fields marked * are required), and then click on `Continue'.
E-mail address* 
Repeat e-mail address* 
(for error checking) 

Format*   PDF (US $40)
   HTML (US $40)
   PDF+HTML (US $50)
In order for VAT to be shown for your country javascript needs to be enabled.

VAT number 
(non-UK EC countries only) 
Country* 
 

Terms and conditions of use
Contact us

Follow Acta Cryst. C
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds