Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270199015267/sk1352sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270199015267/sk1352Isup2.hkl |
CCDC reference: 143256
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,C═O), 1595, 1480 (s, C═C 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%.
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.
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.
C7H5BrO2 | Dx = 1.912 Mg m−3 |
Mr = 201.01 | Melting point: 405(1) K |
Orthorhombic, P212121 | Mo Kα radiation, λ = 0.71073 Å |
a = 3.974 (3) Å | Cell parameters from 25 reflections |
b = 9.164 (8) Å | θ = 8.5–17.1° |
c = 19.172 (6) Å | µ = 5.81 mm−1 |
V = 698.2 (8) Å3 | T = 293 K |
Z = 4 | Block, light yellow |
F(000) = 392 | 0.38 × 0.32 × 0.32 mm |
Enraf-Nonius CAD-4 diffractometer | 925 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.035 |
Graphite monochromator | θmax = 25.0°, θmin = 3.1° |
profile data from ω–2θ scans | h = 0→4 |
Absorption correction: ψ scan (North et al., 1968) | k = −10→10 |
Tmin = 0.126, Tmax = 0.156 | l = −22→22 |
2879 measured reflections | 3 standard reflections every 180 min |
1225 independent reflections | intensity decay: 8.5% |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.023 | H 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 reflections | Δρmax = 0.38 e Å−3 |
92 parameters | Δρmin = −0.27 e Å−3 |
0 restraints | Absolute structure: Flack (1983) |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: −0.014 (17) |
C7H5BrO2 | V = 698.2 (8) Å3 |
Mr = 201.01 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 3.974 (3) Å | µ = 5.81 mm−1 |
b = 9.164 (8) Å | T = 293 K |
c = 19.172 (6) Å | 0.38 × 0.32 × 0.32 mm |
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 = 0.156 | 3 standard reflections every 180 min |
2879 measured reflections | intensity decay: 8.5% |
1225 independent reflections |
R[F2 > 2σ(F2)] = 0.023 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.051 | Δρmax = 0.38 e Å−3 |
S = 1.05 | Δρmin = −0.27 e Å−3 |
1225 reflections | Absolute structure: Flack (1983) |
92 parameters | Absolute structure parameter: −0.014 (17) |
0 restraints |
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. |
x | y | z | Uiso*/Ueq | ||
Br | 0.13537 (10) | 0.63600 (4) | 0.11874 (2) | 0.05706 (14) | |
O1 | −0.4577 (7) | 0.8721 (3) | 0.27615 (12) | 0.0566 (7) | |
O2 | −0.2227 (9) | 1.2735 (2) | 0.10229 (12) | 0.0585 (8) | |
H2 | −0.3036 | 1.3032 | 0.1390 | 0.088* | |
C1 | −0.1626 (9) | 0.8998 (3) | 0.17039 (15) | 0.0340 (7) | |
C2 | 0.0121 (8) | 0.8364 (3) | 0.1155 (2) | 0.0399 (8) | |
C3 | 0.1044 (10) | 0.9167 (4) | 0.05813 (17) | 0.0445 (8) | |
H3 | 0.2211 | 0.8724 | 0.0218 | 0.053* | |
C4 | 0.0246 (10) | 1.0624 (4) | 0.0543 (2) | 0.0472 (10) | |
H4 | 0.0874 | 1.1166 | 0.0154 | 0.057* | |
C5 | −0.1494 (9) | 1.1287 (3) | 0.10838 (15) | 0.0413 (7) | |
C6 | −0.2411 (9) | 1.0487 (3) | 0.16615 (18) | 0.0392 (9) | |
H6 | −0.3558 | 1.0937 | 0.2026 | 0.047* | |
C7 | −0.2779 (9) | 0.8206 (3) | 0.23225 (19) | 0.0435 (9) | |
H7 | −0.2076 | 0.7245 | 0.2379 | 0.052* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Br | 0.0556 (2) | 0.04707 (19) | 0.0685 (2) | 0.0137 (2) | 0.0018 (3) | −0.0053 (2) |
O1 | 0.0767 (18) | 0.0522 (14) | 0.0408 (13) | −0.0061 (16) | 0.0174 (14) | −0.0004 (14) |
O2 | 0.090 (2) | 0.0397 (13) | 0.0453 (15) | 0.0027 (13) | 0.0082 (15) | 0.0079 (11) |
C1 | 0.0307 (18) | 0.0394 (16) | 0.0318 (17) | −0.0009 (18) | −0.0052 (18) | −0.0010 (13) |
C2 | 0.0336 (15) | 0.0414 (17) | 0.045 (2) | 0.0019 (13) | −0.0074 (18) | −0.0009 (19) |
C3 | 0.043 (2) | 0.0556 (18) | 0.0345 (19) | 0.005 (2) | 0.001 (2) | −0.0081 (16) |
C4 | 0.050 (2) | 0.057 (2) | 0.035 (2) | −0.0068 (18) | 0.0030 (18) | 0.0024 (17) |
C5 | 0.0470 (18) | 0.0420 (15) | 0.0350 (18) | 0.003 (2) | −0.004 (2) | 0.0053 (18) |
C6 | 0.044 (2) | 0.0408 (18) | 0.033 (2) | 0.0007 (15) | 0.0007 (16) | 0.0003 (15) |
C7 | 0.049 (2) | 0.0407 (18) | 0.041 (2) | −0.0030 (16) | 0.0000 (18) | 0.0030 (15) |
Br—C2 | 1.902 (3) | C3—C4 | 1.374 (5) |
O1—C7 | 1.201 (4) | C3—H3 | 0.9300 |
O2—C5 | 1.364 (4) | C4—C5 | 1.386 (5) |
O2—H2 | 0.8200 | C4—H4 | 0.9300 |
C1—C2 | 1.388 (5) | C5—C6 | 1.377 (4) |
C1—C6 | 1.402 (4) | C6—H6 | 0.9300 |
C1—C7 | 1.464 (5) | C7—H7 | 0.9300 |
C2—C3 | 1.374 (5) | ||
C5—O2—H2 | 109.5 | C3—C4—H4 | 120.0 |
C2—C1—C6 | 118.3 (3) | C5—C4—H4 | 120.0 |
C2—C1—C7 | 124.3 (3) | O2—C5—C6 | 122.0 (3) |
C6—C1—C7 | 117.4 (3) | O2—C5—C4 | 118.0 (3) |
C3—C2—C1 | 121.1 (3) | C6—C5—C4 | 120.0 (3) |
C3—C2—Br | 118.3 (3) | C5—C6—C1 | 120.4 (3) |
C1—C2—Br | 120.6 (3) | C5—C6—H6 | 119.8 |
C2—C3—C4 | 120.1 (3) | C1—C6—H6 | 119.8 |
C2—C3—H3 | 120.0 | O1—C7—C1 | 124.0 (3) |
C4—C3—H3 | 120.0 | O1—C7—H7 | 118.0 |
C3—C4—C5 | 120.1 (3) | C1—C7—H7 | 118.0 |
C6—C1—C2—C3 | −0.5 (5) | C3—C4—C5—C6 | 0.3 (6) |
C7—C1—C2—C3 | 178.2 (3) | O2—C5—C6—C1 | 179.7 (4) |
C6—C1—C2—Br | 178.6 (2) | C4—C5—C6—C1 | −0.7 (5) |
C7—C1—C2—Br | −2.7 (5) | C2—C1—C6—C5 | 0.7 (5) |
C1—C2—C3—C4 | 0.1 (5) | C7—C1—C6—C5 | −178.0 (3) |
Br—C2—C3—C4 | −179.0 (3) | C2—C1—C7—O1 | −172.2 (4) |
C2—C3—C4—C5 | 0.0 (6) | C6—C1—C7—O1 | 6.5 (5) |
C3—C4—C5—O2 | 179.9 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H2···O1i | 0.82 | 1.99 | 2.804 (4) | 175 |
Symmetry code: (i) −x−1, y+1/2, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | C7H5BrO2 |
Mr | 201.01 |
Crystal system, space group | Orthorhombic, P212121 |
Temperature (K) | 293 |
a, b, c (Å) | 3.974 (3), 9.164 (8), 19.172 (6) |
V (Å3) | 698.2 (8) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 5.81 |
Crystal size (mm) | 0.38 × 0.32 × 0.32 |
Data collection | |
Diffractometer | Enraf-Nonius CAD-4 diffractometer |
Absorption correction | ψ scan (North et al., 1968) |
Tmin, Tmax | 0.126, 0.156 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 2879, 1225, 925 |
Rint | 0.035 |
(sin θ/λ)max (Å−1) | 0.594 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.023, 0.051, 1.05 |
No. of reflections | 1225 |
No. of parameters | 92 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.38, −0.27 |
Absolute structure | Flack (1983) |
Absolute structure parameter | −0.014 (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.
C2—C1—C6 | 118.3 (3) | C3—C4—C5 | 120.1 (3) |
C3—C2—C1 | 121.1 (3) | C6—C5—C4 | 120.0 (3) |
C2—C3—C4 | 120.1 (3) | C5—C6—C1 | 120.4 (3) |
C2—C1—C7—O1 | −172.2 (4) | C6—C1—C7—O1 | 6.5 (5) |
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H2···O1i | 0.82 | 1.99 | 2.804 (4) | 174.6 |
Symmetry code: (i) −x−1, y+1/2, −z+1/2. |
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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.