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

In a new coumarin derivative obtained from the reaction of 3-acetyl-4-hy­droxy-2H-chromen-2-one with bromine in acetic acid, the hy­droxy group in involved in an intra­molecular O—H...O hydrogen bond. In the crystal, π–π inter­actions between the rings of the bicycle pack mol­ecules into stacks along the b axis.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.009 Å
• R factor = 0.057
• wR factor = 0.133
• Data-to-parameter ratio = 20.5

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT026_ALERT_3_B Ratio Observed / Unique Reflections too Low ....         34 %

Alert level C
PLAT029_ALERT_3_C _diffrn_measured_fraction_theta_full Low .......      0.968 Note
PLAT242_ALERT_2_C Low       Ueq as Compared to Neighbors for .....        C11 Check
PLAT341_ALERT_3_C Low Bond Precision on  C-C Bonds ...............     0.0086 Ang.
PLAT480_ALERT_4_C Long H...A H-Bond Reported H2     ..  O2      ..       2.62 Ang.
PLAT906_ALERT_3_C Large K value in the Analysis of Variance ......     21.386 Check
PLAT906_ALERT_3_C Large K value in the Analysis of Variance ......      7.210 Check
PLAT906_ALERT_3_C Large K value in the Analysis of Variance ......      2.082 Check
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600         70 Report

Alert level G
PLAT005_ALERT_5_G No _iucr_refine_instructions_details  in the CIF     Please Do !
PLAT899_ALERT_4_G SHELXL97   is Deprecated and Succeeded by SHELXL       2014 Note
PLAT912_ALERT_4_G Missing # of FCF Reflections Above STh/L=  0.600        118 Note

   0 ALERT level A = Most likely a serious problem - resolve or explain
   1 ALERT level B = A potentially serious problem, consider carefully
   8 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   3 ALERT level G = General information/check it is not something unexpected

   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
   7 ALERT type 3 Indicator that the structure quality may be low
   3 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. 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 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.

S2. 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.

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].

S3. 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).

S4. 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 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.

S5. Refinement

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

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

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

	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

Crystal data

C11H6Br2O4	Z = 4
Mr = 361.98	F(000) = 696
Monoclinic, P21/n	Dx = 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) Å^3	0.15 × 0.12 × 0.10 mm

Data collection

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

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)] = 0.057	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.133	H atoms treated by a mixture of independent and constrained refinement
S = 0.96	w = 1/[σ^2(Fo^2) + (0.0409P)^2 + 0.259P] where P = (Fo^2 + 2Fc^2)/3
3234 reflections	(Δ/σ)max < 0.001
158 parameters	Δρmax = 0.43 e Å^−3
0 restraints	Δρmin = −0.48 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	0.56249 (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 (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
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)

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)

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···O2^i	0.98	2.51	3.362 (8)	146
C2—H2···O2^ii	0.93	2.62	3.458 (8)	151

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