2-Bromo-5-hydroxybenzaldehyde

Article abstract of DOI:10.1107/S0108270199015267

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) A. The Br atom deviates significantly from the plane of the ring and the aldehyde group is twisted by 7.1 (5)° around the Csp²-C_arylbond. 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.

Full text of DOI:10.1107/S0108270199015267

organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
ISSN 0108-2701
2-Bromo-5-hydroxybenzaldehyde
A. Matos Beja,a J. A. PaixÄao,a* M. Ramos Silva,a L. Alte da
Veiga,a A. M. d'A. Rocha Gonsalvesb and A. C. Serrac
a
Ã
Â
Departamento de Fõsica, Faculdade de Ciencias e Tecnologia, Universidade de
b
Â
Coimbra, P-3000 Coimbra, Portugal, Departamento de Quõmica, Faculdade de
Figure 1
ORTEPII (Johnson, 1976) plot of the title compound. Displacement
ellipsoids are drawn at the 50% probability level.
Ã
Ciencias e Tecnologia, Universidade de Coimbra, P-3000 Coimbra, Portugal, and
c
Â
Â
Universidade Catolica Portuguesa, Polo da Figueira da Foz, P-3080 Figueira da Foz,
Portugal
identi®ed by X-ray diffraction as the title compound, the 2-
bromo-5-hydroxybenzaldehyde isomer, (I) (Fig. 1).
Correspondence e-mail: jap@pollux.fis.uc.pt
The internal bond angles of the ring at C1 [118.3 (3)ꢁ] and
C2 [121.1 (3)ꢁ] deviate signi®cantly from the ideal value of
120ꢁ. While the hydroxyl-O2 atom is coplanar with the
benzene ring within experimental uncertainty, both the alde-
hyde group and the Br atom are tilted out from this plane. The
deviations from the least-squares benzene ring plane are Br
Received 16 November 1999
Accepted 24 November 1999
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
Ê
0.032 (5), C7 0.042 (5) and O1 0.181 (6) A. The C7ÐC1
Ê
groups, with an OÁ Á ÁO distance of 2.804 (4) A. The Br atom
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 the C6ÐC1ÐC7 [117.4 (3)ꢁ] and C2ÐC1ÐC7
[124.3 (3)ꢁ] bond angles. In addition, the aldehyde group is
rotated by 7.1 (5)ꢁ around the C1ÐC7 bond. These effects
may be due to a steric interaction between the formyl-H atom
and the bulky Br atom, but may also re¯ect 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) calcu-
lations using the computer code GAMESS (Schmidt et al.,
1993). The atomic wave-functions of the light atoms were
expanded on a standard 6-31G(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 ®eld calcula-
deviates signi®cantly from the plane of the ring and the
aldehyde group is twisted by 7.1 (5)ꢁ around the Csp2ÐCaryl
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.
Comment
We have recently reported the structures of 2,4-dibromo and
2,4,6-tribromo derivatives of m-hydroxybenzaldehyde (Matos
Beja, PaixaÄo, Ramos Silva, Alte da Veiga et al., 1997; Matos
Beja, PaixaÄo, Ramos Silva, 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 monobromo
derivative 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)
5
3
tion was iterated until a Áꢀ of less than 10 bohr was
achieved. The ®nal equilibrium geometry at the minimum
energy had a maximum gradient in internal coordinates of
carried out the bromination in acetic acid and isolated a
product with a very similar melting point to that obtained by
Hodgson & Beard and identi®ed it as the 4-bromoderivative.
In order to clarify which isomer is obtained by mono-
bromination of m-hydroxybenzaldehyde we followed
Pandya's conditions as well as Hodgson & Beard's and have
isolated the same compound in both conditions. This was
Figure 2
Projection of the crystal structure on the bc plane showing the hydrogen-
bonding chains running along the b axis.
ꢀ
354 # 2000 International Union of Crystallography
Printed in Great Britain ± all rights reserved
Acta Cryst. (2000). C56, 354±355

organic compounds
5
1
5
10
Hartree bohr
or 10
Hartree rad 1. A similar
Table 2
Hydrogen-bonding geometry (A, ).
ꢁ
Ê
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 C1ÐC7 bond [calculated values: C2ÐC1ÐC7
DFT 123.53ꢁ; MO±HF 123.55ꢁ, C6ÐC1ÐC7 DFT MO±HF
117.38ꢁ]. 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 C1ÐC7 bond is due to the intermolecular interaction
between the aldehyde and hydroxyl groups.
DÐHÁ Á ÁA
O2ÐH2Á Á ÁO1i
Symmetry code: (i)
DÐH
HÁ Á ÁA
DÁ Á ÁA
DÐHÁ Á ÁA
0.82
x; 12 ‡ y; 12 z.
1.99
2.804 (4)
175
1
Data collection
Enraf±Nonius CAD-4 diffract-
ometer
Pro®le data from !±2ꢄ scans
Absorption correction: scan
(North et al., 1968)
Tmin = 0.126, Tmax = 0.156
2879 measured re¯ections
762 independent re¯ections (plus
463 Friedel-related re¯ections)
925 re¯ections with I > 2ꢆ(I)
Rint = 0.035
ꢄmax = 24.97ꢁ
h = 0 ! 4
k = 10 ! 10
l = 22 ! 22
3 standard re¯ections
frequency: 180 min
intensity decay: 8.5%
Re®nement
The molecules are stacked in layers perpendicular to the
short a axis. The hydroxyl and carbonyl group interact via a
Re®nement on F2
R[F2 > 2ꢆ(F2)] = 0.023
wR(F2) = 0.051
S = 1.048
1225 re¯ections
92 parameters
H atoms constrained
w = 1/[ꢆ2(Fo2) + (0.023P)2 + 0.103P]
where P = (Fo2 + 2Fc2)/3
(Á/ꢆ)max = 0.001
Ê
hydrogen bond [O2Á Á ÁO1 2.804 (4) A] forming zigzag chains
3
Ê
Áꢀmax = 0.38 e A
running along the b axis (Fig. 2). Similar chains were found in
the crystal structure of 2,4,6-tribromo derivative 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 OÐHÁ Á ÁO bond distances
and angles, it appears that the strongest hydrogen bonds occur
in the monobromo derivative.
3
Ê
0.27 e A
Áꢀmin
=
Absolute structure: Flack (1983)
Flack parameter = 0.014 (17)
Data collection: CAD-4 Software (Enraf±Nonius, 1989); cell
re®nement: CAD-4 Software; data reduction: HELENA (Spek, 1997);
program(s) used to solve structure: SHELXS97 (Sheldrick, 1990);
program(s) used to re®ne structure: SHELXL97 (Sheldrick, 1997);
molecular graphics: ORTEPII (Johnson, 1976); software used to
prepare material for publication: SHELXL97.
Experimental
The title compound was prepared by slowly adding bromine (0.87 ml)
to a solution of 3-hydroxybenzaldehyde (2.0 g) in glacial acetic acid
(10 ml). After 3 h, water was added to precipitate a solid and the
mixture was left overnight in the refrigerator. The solid was ®ltered
and recrystallized in water to give 2.25 g of the title compound [ꢁ =
68%; m.p. 405±406 K, literature 406 K (Pandya et al., 1952)]. MS (EI)
The authors are indebted to Dr J. C. Prata Pina for his
invaluable assistance in the maintenance of the CAD-4
diffractometer. This work was supported by FundacËaÄo para a
Ã
Ciencia e Tecnologia (FCT) and Chymiotechnon.
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: SK1352). Services for accessing these data are
described at the back of the journal.
1
201 (M+). H NMR (300 MHz, CDCl3/DMSO-d6, p.p.m.): ꢂ 10.1 (s,
1H, CHO), 9.7 (s, 1H, OH), 7.4 (d, 1H, J = 8.7 Hz, CH-aryl), 7.2 (d,
C
1H, J = 3.0 Hz, CH-aryl), 6.9 (dd, 1H, J = 8.7 and 3.0 Hz, CH-aryl); 13
NMR (75.5 MHz, CDCl3/DMSO-d6, p.p.m.): 191.4, 157.1, 134.0, 133.3,
References
1
123.1, 115.3, 114.9; IR (KBr) cm 3331 (m) (OH), 1684 (s, C O),
Binning, R. C. Jr & Curtiss, L. A. (1990). J. Comput. Chem. 11, 1206±1216.
Enraf±Nonius (1989). CAD-4 Software. Version 5.0. Enraf±Nonius, Delft, The
Netherlands.
1595, 1480 (s, C C aromatic), 1305 (s), 1236 (s), 1170 (m, CÐO), 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%.
Flack, H. D. (1983). Acta Cryst. A39, 876±881.
Hodgson, H. H. & Beard, H. G. (1925). J. Chem. Soc. 127, 875±881.
Johnson, C. K. (1976). ORTEPII. Report ORNL-5138. Oak Ridge National
Laboratory, Tennessee, USA.
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Gonsalves, A. M. d'A., Pereira, M. M. & Serra, A. C. (1997). Acta Cryst.
C53, 494±496.
Matos Beja, A., PaixaÄo, J. A., Ramos Silva, M., Rocha Gonsalves, A. M. d'A.,
Pereira, M. M. & Serra, A. C. (1997). Z. Kristallogr. New Cryst. Struct. 213,
139±140.
North, A. C. T., Phillips, D. C. & Mathews, F. S. (1968). Acta Cryst. A24, 351±
359.
Crystal data
C7H5BrO2
Mr = 201.01
Orthorhombic, P212121
Ê
a = 3.974 (3) A
Ê
b = 9.164 (8) A
c = 19.172 (6) A
Ê
V = 698.2 (8) A
Z = 4
Dx = 1.912 Mg m
Mo Kꢃ radiation
Cell parameters from 25
re¯ections
ꢄ = 8.51±17.13ꢁ
1
ꢅ = 5.814 mm
T = 293 (2) K
Ê
3
Block, light yellow
0.38 Â 0.32 Â 0.32 mm
3
Pandya, K. C., Pandya, R. B. K. & Singh, R. N. (1952). J. Indian Chem. Soc. 29,
363±367.
Schmidt, M. W., Baldridge, K. K., Boatz, J. A., Elbert, S. T., Gordon, M. S.,
Jensen, J. J., Koseki, S., Matsunaga, N., Nguyen, K. A., Su, S., Windus, T. L.,
Dupuis, M. & Montgomery, J. A. (1993). J. Comput. Chem. 14, 1347±1363.
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Table 1
Selected geometric parameters (ꢁ).
C2ÐC1ÐC6
C3ÐC2ÐC1
C2ÐC3ÐC4
118.3 (3)
121.1 (3)
120.1 (3)
C3ÐC4ÐC5
C6ÐC5ÐC4
C5ÐC6ÐC1
120.1 (3)
120.0 (3)
120.4 (3)
È
Sheldrick, G. M. (1997). SHELXL97. University of Gottingen, Germany.
Spek, A. L. (1997). HELENA. University of Utrecht, The Netherlands.
St-Amant, A., Goh, S. K. & Gallant, R. T. (1998). DeFT2.2 Software Package.
University of Ottawa, Ontario, Canada.
C2ÐC1ÐC7ÐO1
172.2 (4)
C6ÐC1ÐC7ÐO1
6.5 (5)
Vosko, H., Wilk, L. & Nusair, M. (1980). Can. J. Phys. 58, 1200±1211.
ꢀ
Acta Cryst. (2000). C56, 354±355
A. Matos Beja et al. C7H5BrO2 355