A new polymorph of 2-bromo-5-hydroxy­benz­aldehyde

A new polymorph of 2-bromo-5-hydroxy­benz­aldehyde, C₇H₅BrO₂, is reported. In this new form a pair of hydrogen bonds link mol­ecules related by an inversion centre. The Br atom deviates significantly from the plane of the benzene ring and the aldehyde group is twisted by 10.0 (5)° around the Csp²-C_aryl bond.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• R factor = 0.030
• wR factor = 0.083
• Data-to-parameter ratio = 12.7

checkCIF/PLATON results

No syntax errors found



Alert level C
ABSTM02_ALERT_3_C  The ratio of expected to reported Tmax/Tmin(RR) is > 1.10
            Tmin and Tmax reported:      0.520     0.550
            Tmin and Tmax expected:      0.352     0.550
            RR =      1.475
            Please check that your absorption correction is appropriate.
PLAT029_ALERT_3_C _diffrn_measured_fraction_theta_full Low .......       0.97

Author Response: some electronic problems during data collection led to a few reflections measured with a ultra-fast scan. The measured intensities did not correspond to a reliable experimental value and were omitted from the reflection list. We believe that the number_of_reflections/parameters ratio is acceptable as it is.

PLAT060_ALERT_3_C Ratio Tmax/Tmin (Exp-to-Rep) (too) Large .......       1.47
PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density ....       2.92
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?
PLAT341_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ...          7

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   6 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
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   4 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software; data reduction: HELENA (Spek, 2003); 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.

2-bromo-5-hydroxybenzaldehyde

Crystal data

C7H5BrO2	F(000) = 392
Mr = 201.01	Dx = 1.966 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 11.235 (6) Å	Cell parameters from 25 reflections
b = 4.038 (5) Å	θ = 10.4–16.9°
c = 17.057 (8) Å	µ = 5.98 mm^−1
β = 118.66 (3)°	T = 293 K
V = 679 (1) Å^3	Piramid, pink
Z = 4	0.35 × 0.15 × 0.10 mm

Data collection

Enraf-Nonius CAD-4 diffractometer	866 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.021
Graphite monochromator	θmax = 25.1°, θmin = 2.5°
profile data from ω–2θ scans	h = −13→13
Absorption correction: ψ scan (North et al., 1968)	k = −4→0
Tmin = 0.52, Tmax = 0.55	l = −13→20
1228 measured reflections	3 standard reflections every 180 min
1172 independent reflections	intensity decay: 8%

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)] = 0.030	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.083	H-atom parameters constrained
S = 1.04	w = 1/[σ^2(Fo^2) + (0.0407P)^2 + 1.0851P] where P = (Fo^2 + 2Fc^2)/3
1172 reflections	(Δ/σ)max < 0.001
92 parameters	Δρmax = 0.87 e Å^−3
0 restraints	Δρmin = −0.30 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	0.27698 (5)	0.76907 (12)	−0.14132 (3)	0.04613 (19)
O2	0.2831 (3)	0.2794 (9)	0.19517 (19)	0.0540 (9)
H2	0.2123	0.1859	0.1847	0.081*
O1	−0.0367 (3)	0.1222 (10)	−0.1363 (2)	0.0588 (10)
C2	0.2736 (4)	0.6037 (11)	−0.0378 (3)	0.0378 (9)
C1	0.1645 (4)	0.4180 (10)	−0.0444 (3)	0.0351 (9)
C5	0.2755 (4)	0.3857 (13)	0.1168 (3)	0.0410 (10)
C7	0.0487 (5)	0.3182 (12)	−0.1303 (3)	0.0443 (11)
H7	0.0408	0.4107	−0.1825	0.053*
C3	0.3821 (5)	0.6768 (11)	0.0446 (3)	0.0439 (11)
H3	0.4543	0.8003	0.0481	0.053*
C6	0.1675 (4)	0.3124 (11)	0.0345 (3)	0.0388 (10)
H6	0.0952	0.1904	0.0314	0.047*
C4	0.3841 (5)	0.5674 (12)	0.1223 (3)	0.0457 (11)
H4	0.4578	0.6155	0.1777	0.055*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0537 (3)	0.0464 (3)	0.0460 (3)	−0.0043 (3)	0.0301 (2)	0.0001 (3)
O2	0.0552 (19)	0.069 (2)	0.0363 (16)	−0.0057 (19)	0.0212 (14)	0.0051 (18)
O1	0.0403 (17)	0.083 (2)	0.0430 (18)	−0.0203 (19)	0.0117 (15)	0.0028 (18)
C2	0.044 (2)	0.033 (2)	0.042 (2)	0.0012 (19)	0.025 (2)	−0.002 (2)
C1	0.032 (2)	0.033 (2)	0.037 (2)	0.0026 (18)	0.0135 (17)	0.0002 (19)
C5	0.044 (2)	0.041 (2)	0.036 (2)	0.002 (2)	0.017 (2)	−0.0027 (19)
C7	0.043 (2)	0.051 (3)	0.035 (2)	0.002 (2)	0.0155 (19)	0.006 (2)
C3	0.043 (2)	0.039 (3)	0.049 (2)	−0.006 (2)	0.021 (2)	−0.006 (2)
C6	0.035 (2)	0.041 (3)	0.042 (2)	−0.0019 (19)	0.0189 (18)	0.000 (2)
C4	0.046 (3)	0.045 (3)	0.038 (2)	−0.003 (2)	0.015 (2)	−0.008 (2)

Geometric parameters (Å, º)

Br1—C2	1.905 (4)	C5—C6	1.377 (6)
O2—C5	1.367 (5)	C5—C4	1.388 (7)
O2—H2	0.8200	C7—H7	0.9300
O1—C7	1.209 (6)	C3—C4	1.387 (6)
C2—C3	1.380 (6)	C3—H3	0.9300
C2—C1	1.395 (6)	C6—H6	0.9300
C1—C6	1.397 (6)	C4—H4	0.9300
C1—C7	1.474 (6)
C5—O2—H2	109.5	O1—C7—H7	118.3
C3—C2—C1	120.6 (4)	C1—C7—H7	118.3
C3—C2—Br1	118.0 (3)	C2—C3—C4	120.5 (4)
C1—C2—Br1	121.4 (3)	C2—C3—H3	119.8
C2—C1—C6	118.2 (4)	C4—C3—H3	119.8
C2—C1—C7	123.4 (4)	C5—C6—C1	121.2 (4)
C6—C1—C7	118.4 (4)	C5—C6—H6	119.4
O2—C5—C6	122.7 (4)	C1—C6—H6	119.4
O2—C5—C4	117.3 (4)	C3—C4—C5	119.5 (4)
C6—C5—C4	120.0 (4)	C3—C4—H4	120.3
O1—C7—C1	123.3 (4)	C5—C4—H4	120.3
C3—C2—C1—C6	0.8 (7)	O2—C5—C6—C1	−178.4 (4)
Br1—C2—C1—C6	−178.3 (3)	C4—C5—C6—C1	−0.1 (7)
C3—C2—C1—C7	−177.1 (4)	C2—C1—C6—C5	−0.7 (7)
Br1—C2—C1—C7	3.8 (6)	C7—C1—C6—C5	177.3 (4)
C2—C1—C7—O1	170.0 (5)	C2—C3—C4—C5	−0.6 (7)
C6—C1—C7—O1	−7.9 (7)	O2—C5—C4—C3	179.1 (4)
C1—C2—C3—C4	−0.2 (7)	C6—C5—C4—C3	0.7 (7)
Br1—C2—C3—C4	179.0 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···O1^i	0.82	2.14	2.939 (5)	167

Symmetry code: (i) −x, −y, −z.