Crystal structure of 3-(2,2-di­bromo­acet­yl)-4-hy­droxy-2H-chromen-2-one

Brahmia, A.; Ghouili, A.; Ben Hassen, R.

doi:10.1107/S2056989014027947

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Volume 71| Part 2| February 2015| Pages 121-123

doi:10.1107/S2056989014027947

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Crystal structure of 3-(2,2-dibromoacetyl)-4-hydroxy-2H-chromen-2-one

Ameni Brahmia,^a Afef Ghouili ^a and Rached Ben Hassen ^a ^*

^aUnité de Chimie des Matériaux et de l'Environnement UR11ES25, ISSBAT, Université de Tunis-El Manar, 9, Avenue Dr. Zoheir SAFI, 1006 Tunis, Tunisia
^*Correspondence e-mail: rached.benhassen@fss.rnu.tn

Edited by V. V. Chernyshev, Moscow State University, Russia (Received 27 November 2014; accepted 22 December 2014; online 3 January 2015)

The title compound, C₁₁H₆Br₂O₄, is a new coumarin derivative obtained from the reaction of 3-acetyl-4-hydroxy-2H-chromen-2-one with bromine in acetic acid. The hydroxyl group in involved in an intramolecular O—H⋯O hydrogen bond. In the crystal, π–π interactions between the rings of the bicycle [intercentroid distances = 3.498 (2) and 3.539 (2) Å] pack molecules into stacks along the b axis, and weak intermolecular C—H⋯O hydrogen bonds further link these stacks into layers parallel to the ab plane.

Keywords: crystal structure; coumarin derivatives; dibromation; hydrogen bonding; π–π interactions.

CCDC reference: 1040655

1. Chemical context

3-Acetyl-4-hydroxy-2H-chromen-2-one is one of the well-known 3-substituted-4-hydroxycoumarins, which form a class of fused-ring heterocycles and occur widely among natural products. Several natural products with the coumarinic moiety exhibit interesting biological properties such as anti-oxidant and antibacterial (Kayser & Kolodziej, 1997 ). They also possess pharmacological activities including anti-inflammatory (Mahidol et al., 2004 ), anticancer (Wang et al., 2002 ) and inhibition of platelet aggregation (Cravotto et al., 2001 ). These derivatives are very susceptible to electrophilic substitutions (Dou et al., 1969 ); their reaction with bromine can give rise to several compounds used as intermediate products which are susceptible to interesting substitutions (Takase et al., 1971 ) in a wide range of organic syntheses. The bromination of these compounds increases their anticonvulsant activity (Dimmock et al., 2000 ), which gives them pharmacological importance. Thus, as part of a study of the effects of substituents on the crystal structures of 3-acetyl-4-hydroxycoumarins (Traven et al., 2000 ), the structure of 3-(2,2-dibromoacetyl)-4-hydroxy-2H-chromen-2-one, (I), has been determined.

2. Structural commentary

In the title compound (Fig. 1), the hydroxy group is involved in formation of an intramolecular O—H⋯O hydrogen bond (Table 1). In fact, the O3—H5 distance of 0.94 (7) Å has decreased from 1.02 (3) Å, observed in the starting reagent 3-acetyl-4-hydroxy-2H-chromen-2-one (Lyssenko & Antipin, 2001 ). The H5⋯O4 distance of 1.65 (7) Å is elongated compared with its value in the parent compound [1.45 (3) Å], and the O3—H5⋯O4 angle of 147 (6)° is significantly smaller than that found for the starting reagent [161 (2)°]. This trend has already been observed in the fluorinated compound 2-difluoroacetyl-1,3-cyclohexadione (Grieco et al., 2011 ), in which the O3—H5 and H5⋯O4 distances are even more affected (0.908 and 1.658 Å respectively). These observations can be easily understood from the point of view of the strong attractive effect of the halogen atoms due to their high electronegativities. All these geometrical parameters are in good agreement with the significant attractor effect of the halogen atoms, which affects the lone pairs of the oxygen atom O4, leading to a decrease of the attractor effect of O4 in the H5⋯O4 hydrogen bond and, consequently, an increase in the H5⋯O4 distance.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H5⋯O4	0.94 (7)	1.65 (7)	2.489 (6)	147 (6)
C11—H11⋯O2	0.98	2.12	2.793 (7)	125
C11—H11⋯O2ⁱ	0.98	2.51	3.362 (8)	146
C2—H2⋯O2ⁱⁱ	0.93	2.62	3.458 (8)	151
Symmetry codes: (i) -x+1, -y+1, -z; (ii) x-1, y, z.

Figure 1
The molecular structure of (I)

, showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. Intramolecular hydrogen bonds are shown as dashed lines.

The C—C and C—O bond lengths in (I) correspond well to those observed in the parent compound, so they are not affected by the α-ketodibromation except for C10—C11 [1.523 (9) Å] which is elongated compared to the distance in the starting reagent [1.485 (2) Å; Lyssenko & Antipin, 2001). This trend had previously been observed in the similar structure of 2-difluoroacetyl-1,3-cyclohexadione (Grieco et al., 2011), in which the difluoration reaction affects the C10—C11 distance [1.529 (2) Å].

3. Supramolecular features

In the crystal structure of (I), the molecules are assembled in a head-to-tail overlapping manner as a result of the π–π interactions between the benzene and lactone rings of neighbouring molecules (Table 2) into stacks along the b-axis direction (Fig. 2). The observed stacking arrangement can be considered as a balance between van der Waals dispersion and repulsion interactions, and electrostatic interactions between two rings of opposed polarity – the benzene ring (high electron density) and the lactone ring (low electron density) (Hunter & Sanders, 1990 ). Weak intermolecular C—H⋯O hydrogen bonds (Table 2) further link these stacks into layers parallel to the ab plane (Fig. 3).

Table 2
Details of π–π interactions: intercentroid distances (Å)

Cg1 and Cg2 are centroids of the C1–C6 and O1/C5–C9 rings, respectively.

Cg1⋯Cg2ⁱ	3.498 (7)
Cg1⋯Cg2ⁱⁱ	3.539 (7)
Symmetry codes: (i) −x, −y + 2, −z; (ii) −x, −y + 1, −z.

Figure 2
A portion of the crystal packing showing one stack of molecules parallel to the b axis.

Figure 3
The crystal packing, viewed down the b axis, showing the intermolecular C—H⋯O hydrogen bonds as thin blue lines.

4. Synthesis and crystallization

An excess amount of bromine dissolved in acetic acid was added dropwise to a solution of 3-acetyl-4-hydroxy-2H-chromen-2-one in acetic acid (Fig. 4). During the reaction, the dropwise addition was made after every disappearance of the brown colour of the bromine. The reaction mixture was maintained under stirring at 373 K until the bromine colour persisted. The resulting solution was left to crystallize at room temperature to obtain transparent crystals of a light-yellow colour. Yield: 70%; m.p. = 375 K.

Figure 4
The synthetic route for (I)

5. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3. The hydroxy atom H5 was located from an electron density difference map and freely refined. C-bound H atoms were fixed geometrically (C—H = 0.93 or 0.98 Å) and refined as riding, with U_iso(H) set to 1.2U_eq of the parent atom.

Table 3
Experimental details

Crystal data
Chemical formula	C₁₁H₆Br₂O₄
M_r	361.98
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	296
a, b, c (Å)	9.399 (4), 6.916 (3), 17.967 (7)
β (°)	97.37 (3)
V (Å³)	1158.4 (8)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	7.00
Crystal size (mm)	0.15 × 0.12 × 0.10

Data collection
Diffractometer	Bruker SMART CCD area detector
Absorption correction	For a sphere (WinGX; Farrugia, 2012 )
T_min, T_max	0.58, 0.75
No. of measured, independent and observed [I > 2σ(I)] reflections	11685, 3234, 1094
R_int	0.089
(sin θ/λ)_max (Å⁻¹)	0.712

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.057, 0.133, 0.96
No. of reflections	3234
No. of parameters	158
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.43, −0.48
Computer programs: SMART and SAINT (Bruker, 2001 ), SHELXS97 and SHELXL97 (Sheldrick, 2008 ), ORTEP-3 for Windows and WinGX (Farrugia, 2012).

Supporting information

CCDC reference: 1040655

Crystal structure: contains datablock I. DOI: 10.1107/S2056989014027947/cv5480sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S2056989014027947/cv5480Isup2.hkl

Supporting information file. DOI: 10.1107/S2056989014027947/cv5480Isup3.cml

checkCIF report

Chemical context top

3-Acetyl-4-hydroxy-2H-chromen-2-one is one of the well-known 3-substituted-4-hydroxycoumarins, which form a class of fused-ring heterocycles and occur widely among natural products. Several natural products with the coumarinic moiety exhibit interesting biological properties such as anti-oxidant and antibacterial (Kayser & Kolodziej, 1997). They possess also pharmacological activities: anti-inflammatory (Mahidol et al., 2004), anticancer (Wang et al., 2002) and inhibition of platelet aggregation (Cravotto et al., 2001). These derivatives are very susceptible to electrophilic substitutions (Dou et al., 1969); their reaction with bromine can give rise to several compounds used as intermediate products susceptible to interesting substitutions (Takase et al., 1971) in a wide range of organic syntheses. The bromination of these compounds increases their anticonvulsant activity (Dimmock et al., 2000), which gives them pharmacological importance. Thus, as part of a study of the effects of substituents on the crystal structures of 3-acetyl-4-hydroxycoumarins (Traven et al., 2000), the structure of 3-(2,2-dibromoacetyl)-4-hydroxy-2H-chromen-2-one, (I), has been determined.

Structural commentary top

In the title compound (Fig. 1), the hydroxy group is involved in formation of an intramolecular O—H···O hydrogen bond (Table 1). In fact, the O3—H5 distance of 0.94 (7) Å has decreased from 1.02 (3) Å, observed in the starting reagent 3-acetyl-4-hydroxy-2H-chromen-2-one (Lyssenko & Antipin, 2001). The H5···O4 distance of 1.65 (7) Å is elongated compared with its value in the parent compound [1.45 (3) Å], and the O3—H5···O4 angle of 147 (6)° is significantly smaller than that found for the starting reagent [161 (2)°]. This trend has already been observed in the fluorinated compound 2-difluoroacetyl-1,3-cyclohexadione (Grieco et al., 2011), in which the O3—H5 and H5···O4 distances are even more affected (0.908 and 1.658 Å respectively). These observations can be easily understood from the point of view of the strong attractive effect of the halogen atoms due to their high electronegativities. All these geometrical parameters are in good agreement with the significant attractor effect of the halogen atoms, which affects the lone pairs of the oxygen atom O4, leading to a decrease of the attractor effect of O4 in the H5···O4 hydrogen bond and, consequently, an increase in the H5···O4 distance.

The C—C and C—O bond lengths in (I) correspond well to those observed in the parent compound, so they are not affected by the α-ketodibromation except for C10—C11 [1.523 (9) Å] which is elongated as compared to that in the starting reagent [1.485 (2) Å; Lyssenko & Antipin, 2001). This trend had previously been observed in the similar structure of 2-difluoroacetyl-1,3-cyclohexadione (Grieco et al., 2011), in which the difluoration reaction affects the C10—C11 distance [1.529 (2) Å].

Supramolecular features top

In the crystal structure of (I), the molecules are assembled in a head-to-tail overlapping manner as a result of the π–π interactions between the benzene and lactone rings of neighbouring molecules (Table 2) into stacks along the b-axis direction (Fig. 2). The observed stacking arrangement can be considered as a balance between van der Waals dispersion and repulsion interactions, and electrostatic interactions between two rings of opposed polarity – the benzene ring (high electron density) and the lactone ring (low electron density) (Hunter & Sanders, 1990). Weak intermolecular C—H···O hydrogen bonds (Table 2) further link these stacks into layers parallel to the ab plane (Fig. 3).

Synthesis and crystallization top

An excess amount of bromine dissolved in acetic acid was added dropwise to a solution of 3-acetyl-4-hydroxy-2H-chromen-2-one in acetic acid (Fig. 4). During the reaction, the drop addition was made after every disappearance of the brown colour of the bromine. The reaction mixture was maintained under stirring at 373 K until the bromine colour persisted. The resulting solution was left to crystallize at room temperature to obtain transparent crystals of a light-yellow colour. Yield: 70%; m.p. = 375 K.

Refinement top

The hydroxy atom H5 was located from an electron density difference map and freely refined. C-bound H atoms were fixed geometrically (C—H = 0.93 or 0.98 Å) and refined as riding, with U_iso(H) set to 1.2U_eq of the parent atom.

Related literature top

For related literature, see: Cravotto et al. (2001); Dimmock et al. (2000); Dou et al. (1969); Grieco et al. (2011); Hunter & Sanders (1990); Kayser & Kolodziej (1997); Lyssenko & Antipin (2001); Mahidol et al. (2004); Takase et al. (1971); Traven et al. (2000); Wang et al. (2002).

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SMART (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: WinGX (Farrugia, 2012).

Figures top

	Fig. 1. The molecular structure of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. Intramolecular hydrogen bonds are shown as dashed lines.
	Fig. 2. A portion of the crystal packing showing one stack of molecules parallel to the b axis.
	Fig. 3. The crystal packing, viewed down the b axis, showing the intermolecular C—H···O hydrogen bonds as thin blue lines.
	Fig. 4. The synthetic route for (I).

3-(2,2-Dibromoacetyl)-4-hydroxy-2H-chromen-2-one top

Crystal data top

C₁₁H₆Br₂O₄	Z = 4
M_r = 361.98	F(000) = 696
Monoclinic, P2₁/n	D_x = 2.076 Mg m⁻³
Hall symbol: -P 2yn	Melting point: 375 K
a = 9.399 (4) Å	Mo Kα radiation, λ = 0.71073 Å
b = 6.916 (3) Å	µ = 7.00 mm⁻¹
c = 17.967 (7) Å	T = 296 K
β = 97.37 (3)°	Needle, yellow
V = 1158.4 (8) Å³	0.15 × 0.12 × 0.10 mm

Data collection top

Bruker SMART CCD area-detector diffractometer	3234 independent reflections
Radiation source: fine-focus sealed tube	1094 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.089
ϕ and ω scans	θ_max = 30.4°, θ_min = 2.3°
Absorption correction: for a sphere (WinGX; Farrugia, 2012)	h = −10→13
T_min = 0.58, T_max = 0.75	k = −6→8
11685 measured reflections	l = −25→25

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.057	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.133	H atoms treated by a mixture of independent and constrained refinement
S = 0.96	w = 1/[σ²(F_o²) + (0.0409P)² + 0.259P] where P = (F_o² + 2F_c²)/3
3234 reflections	(Δ/σ)_max < 0.001
158 parameters	Δρ_max = 0.43 e Å⁻³
0 restraints	Δρ_min = −0.48 e Å⁻³

Crystal data top

C₁₁H₆Br₂O₄	V = 1158.4 (8) Å³
M_r = 361.98	Z = 4
Monoclinic, P2₁/n	Mo Kα radiation
a = 9.399 (4) Å	µ = 7.00 mm⁻¹
b = 6.916 (3) Å	T = 296 K
c = 17.967 (7) Å	0.15 × 0.12 × 0.10 mm
β = 97.37 (3)°

Data collection top

Bruker SMART CCD area-detector diffractometer	3234 independent reflections
Absorption correction: for a sphere (WinGX; Farrugia, 2012)	1094 reflections with I > 2σ(I)
T_min = 0.58, T_max = 0.75	R_int = 0.089
11685 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.057	0 restraints
wR(F²) = 0.133	H atoms treated by a mixture of independent and constrained refinement
S = 0.96	Δρ_max = 0.43 e Å⁻³
3234 reflections	Δρ_min = −0.48 e Å⁻³
158 parameters

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Br1	0.56249 (8)	0.89000 (12)	0.15244 (5)	0.0906 (3)
Br2	0.58984 (10)	0.45607 (13)	0.21230 (4)	0.1029 (4)
O1	0.1772 (4)	0.7341 (5)	−0.05777 (19)	0.0525 (10)
O2	0.4010 (5)	0.6891 (6)	−0.0136 (2)	0.0637 (12)
O3	0.0411 (5)	0.6852 (6)	0.1484 (2)	0.0639 (12)
O4	0.2923 (5)	0.6171 (7)	0.2042 (2)	0.0782 (14)
C1	−0.1597 (7)	0.7718 (8)	0.0249 (3)	0.0552 (16)
H1	−0.1941	0.7656	0.0711	0.066*
C2	−0.2515 (7)	0.8099 (8)	−0.0390 (4)	0.0609 (17)
H2	−0.3490	0.8267	−0.0365	0.073*
C3	−0.1981 (8)	0.8233 (8)	−0.1075 (3)	0.0590 (17)
H3	−0.2612	0.8507	−0.1504	0.071*
C4	−0.0559 (7)	0.7973 (8)	−0.1138 (3)	0.0533 (16)
H4	−0.0219	0.8061	−0.1601	0.064*
C5	0.0358 (7)	0.7576 (7)	−0.0489 (3)	0.0453 (15)
C6	−0.0123 (6)	0.7421 (7)	0.0202 (3)	0.0426 (14)
C7	0.0922 (7)	0.7009 (8)	0.0839 (3)	0.0476 (15)
C8	0.2351 (7)	0.6807 (8)	0.0762 (3)	0.0448 (14)
C9	0.2804 (8)	0.7008 (8)	0.0022 (3)	0.0489 (15)
C10	0.3352 (7)	0.6382 (8)	0.1427 (3)	0.0576 (17)
C11	0.4958 (7)	0.6271 (9)	0.1383 (3)	0.0637 (18)
H11	0.5117	0.5825	0.0883	0.076*
H5	0.117 (8)	0.628 (9)	0.180 (3)	0.08 (2)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br1	0.0551 (5)	0.1001 (6)	0.1139 (7)	−0.0050 (4)	0.0000 (4)	−0.0223 (5)
Br2	0.1112 (8)	0.1317 (8)	0.0614 (5)	0.0584 (6)	−0.0057 (4)	0.0091 (4)
O1	0.044 (3)	0.071 (3)	0.042 (2)	0.005 (2)	0.004 (2)	0.0054 (18)
O2	0.044 (3)	0.093 (3)	0.055 (3)	0.010 (2)	0.008 (2)	0.006 (2)
O3	0.061 (3)	0.088 (3)	0.044 (3)	0.006 (3)	0.012 (2)	−0.003 (2)
O4	0.066 (3)	0.130 (4)	0.037 (2)	0.005 (3)	0.003 (2)	0.001 (2)
C1	0.052 (5)	0.054 (4)	0.062 (4)	−0.001 (3)	0.017 (4)	−0.007 (3)
C2	0.048 (4)	0.054 (4)	0.078 (5)	0.003 (3)	−0.005 (4)	−0.002 (3)
C3	0.062 (5)	0.053 (4)	0.058 (4)	0.002 (3)	−0.006 (4)	0.006 (3)
C4	0.046 (5)	0.054 (4)	0.058 (4)	0.000 (3)	0.001 (3)	0.004 (3)
C5	0.045 (4)	0.035 (4)	0.055 (4)	0.001 (3)	0.003 (3)	0.004 (3)
C6	0.048 (4)	0.036 (4)	0.043 (4)	−0.003 (3)	0.006 (3)	−0.003 (2)
C7	0.059 (5)	0.046 (4)	0.040 (4)	−0.008 (3)	0.016 (3)	−0.004 (3)
C8	0.050 (4)	0.054 (4)	0.031 (3)	0.001 (3)	0.007 (3)	0.000 (3)
C9	0.054 (5)	0.045 (4)	0.048 (4)	0.005 (3)	0.007 (4)	0.000 (3)
C10	0.062 (5)	0.064 (4)	0.045 (4)	0.005 (3)	0.002 (4)	−0.001 (3)
C11	0.058 (5)	0.086 (5)	0.044 (4)	0.011 (4)	−0.006 (3)	−0.004 (3)

Geometric parameters (Å, º) top

Br1—C11	1.930 (6)	C2—H2	0.9300
Br2—C11	1.910 (6)	C3—C4	1.368 (8)
O1—C5	1.368 (6)	C3—H3	0.9300
O1—C9	1.374 (6)	C4—C5	1.386 (7)
O2—C9	1.206 (7)	C4—H4	0.9300
O3—C7	1.315 (6)	C5—C6	1.379 (7)
O3—H5	0.94 (7)	C6—C7	1.438 (7)
O4—C10	1.233 (7)	C7—C8	1.375 (8)
C1—C2	1.370 (7)	C8—C10	1.453 (7)
C1—C6	1.413 (8)	C8—C9	1.454 (8)
C1—H1	0.9300	C10—C11	1.523 (9)
C2—C3	1.391 (8)	C11—H11	0.9800

C5—O1—C9	121.8 (5)	C1—C6—C7	123.8 (5)
C7—O3—H5	103 (4)	O3—C7—C8	123.5 (5)
C2—C1—C6	119.7 (6)	O3—C7—C6	115.4 (6)
C2—C1—H1	120.2	C8—C7—C6	121.1 (5)
C6—C1—H1	120.2	C7—C8—C10	118.4 (5)
C1—C2—C3	119.6 (6)	C7—C8—C9	119.1 (5)
C1—C2—H2	120.2	C10—C8—C9	122.5 (6)
C3—C2—H2	120.2	O2—C9—O1	114.7 (5)
C4—C3—C2	122.2 (6)	O2—C9—C8	127.1 (6)
C4—C3—H3	118.9	O1—C9—C8	118.2 (6)
C2—C3—H3	118.9	O4—C10—C8	120.7 (6)
C3—C4—C5	117.7 (6)	O4—C10—C11	118.7 (5)
C3—C4—H4	121.1	C8—C10—C11	120.6 (6)
C5—C4—H4	121.1	C10—C11—Br2	111.6 (4)
O1—C5—C6	122.1 (5)	C10—C11—Br1	104.7 (4)
O1—C5—C4	115.7 (5)	Br2—C11—Br1	112.2 (3)
C6—C5—C4	122.2 (6)	C10—C11—H11	109.4
C5—C6—C1	118.7 (5)	Br2—C11—H11	109.4
C5—C6—C7	117.5 (6)	Br1—C11—H11	109.4

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H5···O4	0.94 (7)	1.65 (7)	2.489 (6)	147 (6)
C11—H11···O2	0.98	2.12	2.793 (7)	125
C11—H11···O2ⁱ	0.98	2.51	3.362 (8)	146
C2—H2···O2ⁱⁱ	0.93	2.62	3.458 (8)	151

Symmetry codes: (i) −x+1, −y+1, −z; (ii) x−1, y, z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H5···O4	0.94 (7)	1.65 (7)	2.489 (6)	147 (6)
C11—H11···O2	0.98	2.12	2.793 (7)	125
C11—H11···O2ⁱ	0.98	2.51	3.362 (8)	146
C2—H2···O2ⁱⁱ	0.93	2.62	3.458 (8)	151

Symmetry codes: (i) −x+1, −y+1, −z; (ii) x−1, y, z.

Details of π–π interactions: intercentroid distances (Å) top

Cg1 and Cg2 are centroids of the C1–C6 and O1/C5–C9 rings, respectively.

Cg1···Cg2ⁱ	3.498 (7)
Cg1···Cg2ⁱⁱ	3.539 (7)

Symmetry codes: (i) -x, -y + 2, -z; (ii) -x, -y + 1, -z.

Experimental details

Crystal data
Chemical formula	C₁₁H₆Br₂O₄
M_r	361.98
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	296
a, b, c (Å)	9.399 (4), 6.916 (3), 17.967 (7)
β (°)	97.37 (3)
V (Å³)	1158.4 (8)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	7.00
Crystal size (mm)	0.15 × 0.12 × 0.10

Data collection
Diffractometer	Bruker SMART CCD area-detector diffractometer
Absorption correction	For a sphere (WinGX; Farrugia, 2012)
T_min, T_max	0.58, 0.75
No. of measured, independent and observed [I > 2σ(I)] reflections	11685, 3234, 1094
R_int	0.089
(sin θ/λ)_max (Å⁻¹)	0.712

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.057, 0.133, 0.96
No. of reflections	3234
No. of parameters	158
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.43, −0.48

Computer programs: SMART (Bruker, 2001), SAINT (Bruker, 2001), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 2012), WinGX (Farrugia, 2012).

Acknowledgements

Professor A. Ben Salah is acknowledged for his contribution to the X-ray diffraction data collection at the Laboratory of Materials Science and the Environment, University of Sfax, Tunisia.

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Volume 71| Part 2| February 2015| Pages 121-123

doi:10.1107/S2056989014027947

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