6,7-Dihydr­oxy-4-methyl­coumarin

In the title compound, C₁₀H₈O₄, one intra­molecular O—H...O hydrogen bond defines an S(5) pattern. The mol­ecules are linked by one O—H...O and one C—H...O hydrogen bond, forming a centrosymmetric dimer with an edge-fused R₂²(8)R₂²(16)[R₂²(16)] motif; the dimers are linked by a pairs of O—H...O hydrogen bond into a [001] ribbon. Adjacent ribbons are linked by π–π stacking inter­actions with centroid–centroid distances of 3.687 (3) and 3.753 (3) Å.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.006 Å
• R factor = 0.095
• wR factor = 0.295
• Data-to-parameter ratio = 10.8

checkCIF/PLATON results

No syntax errors found



Alert level B
DIFMX01_ALERT_2_B  The maximum difference density is > 0.1*ZMAX*1.00
            _refine_diff_density_max given =      1.071
            Test value =      0.800
PLAT097_ALERT_2_B Maximum (Positive) Residual Density ............       1.07 e/A   

Alert level C
DIFMX02_ALERT_1_C  The maximum difference density is > 0.1*ZMAX*0.75
            The relevant atom site should be identified.
RFACR01_ALERT_3_C  The value of the weighted R factor is > 0.25
            Weighted R factor given   0.295
PLAT029_ALERT_3_C _diffrn_measured_fraction_theta_full Low .......       0.98
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT084_ALERT_2_C High R2 Value ..................................       0.29
PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density ....       2.19
PLAT154_ALERT_1_C The su's on the Cell Angles are Equal  (x 10000)        300 Deg.
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.18
PLAT340_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...          6

   0 ALERT level A = In general: serious problem
   2 ALERT level B = Potentially serious problem
   9 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   3 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   5 ALERT type 2 Indicator that the structure model may be wrong or deficient
   3 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

7-Hydroxycoumarin derivatives are known to have a broad range of biological activities, including inhibition of Acetylcholinesterase and Monoamine Oxidase (Rollinger et al.,2004; Brühlmann et al., 2001), antioxidants (Sharma et al., 2005). The crystal structures of some 7-hydroxycoumarin derivatives (Zhang et al., 2006; Shen et al., 2006) have been described. Here we report the molecular structure of 6,7-dihydroxy-4-methyl-2H-1-benzopyran-2-one, (I).

In the molecule of (I), one intramolecular O—H···O hydrogen bond defines an S(5) pattern (García-Báez et al., 2002) (Fig. 1, Table 1). The molecule is almost planar, the dihedral angle between the benzene and pyran rings is 3.13 (3) Å. The geometric parameters for (I) are normal (Allen et al., 1987).

The molecules of (I) are linked by one O—H···O and one C—H···O hydrogen bonds into a centrosymmetric dimer of R₂²(8)R₂²(16)[R₂²(16)] (García-Báez et al., 2002) ring centred at (1/2, 0, 1/2)(Fig. 2 and Table 1). Atoms O4 and C8 in the molecule at (x, y, z) act as a hydrogen-bond donor to atoms O2 and O1 in the molecule at (1 - x, -y,1 - z), respectively. These dimers are connected by a pair of O—H···O hydrogen bonds into a ribbon in the [0 0 1] direction (Fig. 2 and Table 1). Atoms O3 in the molecules at (x, y, z) and (1 - x, -y, 2 - z) act as a hydrogen-bond donors to atoms O2 in the molecules at (x, y, 1 + z) and (1 - x, -y,1 - z), respectively. These adjacent ribbons are linked by π···π interacions into three-dimensional structure [Cg1···Cg2ⁱ= 3.687 (3) Å, Cg1···Cg2ⁱⁱ= 3.753 (3) Å; symmetry codes: (i)-x,1 - y,1 - z; (ii)1 - x,1 - y.1 - z; where Cg1 is centroid of the ring O1/C1—C4/C9 and Cg2 is centroid of the ring C4—C9.]

Related literature

For related literature, see: Allen et al. (1987); Brühlmann et al. (2001); García-Báez et al. (2002); Rollinger et al. (2004); Sharma et al. (2005); Shen & Zeng (2006); Zhang et al. (2006).

S2. Experimental

The reaction mixture containing 2,3,4-triacetoxy benzene (2.52 g, 10 mmol), acetoacetic ester (1.3 ml, 10 mmol) and phosphoric acid (5.3 ml) was stirred at 363–373 K for 12 h, and then poured into the water. The solid obtained was filtered off, washed with water and dried at room temperature. Colourless crystals of (I) suitable for X-ray structure analysis were obtained by slow evaporation of a ethanol solution with the crude product over three days. (M·P.555–557 K).

S3. Refinement

All H atoms were positioned geometrically and refined as riding on their parent atoms, with C—H = 0.96 Å (methyl), O—H = 0.82 Å (hydroxy) and U_iso(H)= 1.5U_eq(C,O), and C—H = 0.93 Å and U_iso(H) = 1.2U_eq(C) for all other H atoms. The residual peaks (Δρ_max = 1.07 e Å^-3) and R (wR(F²) = 0.295) values are high because of poor crystal quality.

Computing details

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT (Siemens, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997a); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997a); molecular graphics: SHELXTL (Sheldrick, 1997b); software used to prepare material for publication: SHELXTL (Sheldrick, 1997b).

Figures

	Fig. 1. The molecular structure of (I), showing the atom-labelling scheme and intramolecular hydrogen-bonded S(6) ring. Displacement ellipsoids are drawn at the 30% probability level. Dashed line indicate hydrogen bonds.
	Fig. 2. Part of the crystal structure of (I), showing the formation of a [0 0 1] ribbon. For clarity, H atoms not involved in the motifs have been omitted. Dashed lines indicate hydrogen bonds.

6,7-Dihydroxy-4-methylcoumarin

Crystal data

C10H8O4	Z = 2
Mr = 192.16	F(000) = 200
Triclinic, P1	Dx = 1.576 Mg m^−3
Hall symbol: -P 1	Melting point: 555 K
a = 6.839 (2) Å	Mo Kα radiation, λ = 0.71073 Å
b = 7.143 (3) Å	Cell parameters from 520 reflections
c = 9.549 (3) Å	θ = 2.3–26.9°
α = 68.233 (3)°	µ = 0.12 mm^−1
β = 85.262 (3)°	T = 298 K
γ = 69.443 (3)°	Prism, colourless
V = 405.0 (2) Å^3	0.56 × 0.15 × 0.13 mm

Data collection

Bruker SMART CCD area-detector diffractometer	1397 independent reflections
Radiation source: fine-focus sealed tube	807 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.029
ϕ and ω scans	θmax = 25.0°, θmin = 2.3°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −7→8
Tmin = 0.934, Tmax = 0.984	k = −8→8
2098 measured reflections	l = −11→9

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)] = 0.095	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.295	H-atom parameters constrained
S = 1.04	w = 1/[σ^2(Fo^2) + (0.1927P)^2] where P = (Fo^2 + 2Fc^2)/3
1397 reflections	(Δ/σ)max < 0.001
129 parameters	Δρmax = 1.07 e Å^−3
0 restraints	Δρmin = −0.49 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
O1	0.3392 (5)	0.2706 (4)	0.3419 (3)	0.0317 (9)
O2	0.3742 (5)	0.3077 (5)	0.1047 (3)	0.0387 (10)
O3	0.2139 (6)	0.5590 (5)	0.8112 (3)	0.0457 (11)
H3	0.2451	0.4563	0.8916	0.069*
O4	0.3620 (5)	0.1277 (5)	0.8662 (3)	0.0381 (10)
H4	0.4299	0.0067	0.8680	0.057*
C1	0.3200 (7)	0.4023 (7)	0.1939 (4)	0.0293 (11)
C2	0.2386 (7)	0.6265 (7)	0.1609 (5)	0.0330 (12)
H2	0.2153	0.7185	0.0602	0.040*
C3	0.1929 (7)	0.7131 (7)	0.2691 (5)	0.0257 (11)
C4	0.2277 (6)	0.5693 (6)	0.4254 (4)	0.0238 (11)
C5	0.1990 (7)	0.6340 (6)	0.5502 (4)	0.0245 (11)
H5	0.1499	0.7798	0.5341	0.029*
C6	0.2419 (7)	0.4867 (7)	0.6950 (4)	0.0283 (11)
C7	0.3178 (7)	0.2672 (7)	0.7203 (4)	0.0261 (11)
C8	0.3444 (7)	0.1995 (7)	0.6007 (4)	0.0267 (11)
H8	0.3898	0.0538	0.6168	0.032*
C9	0.3021 (6)	0.3523 (6)	0.4558 (4)	0.0230 (11)
C10	0.1105 (8)	0.9506 (7)	0.2279 (5)	0.0376 (13)
H10A	0.1870	0.9891	0.2861	0.056*
H10B	−0.0349	0.9960	0.2486	0.056*
H10C	0.1263	1.0196	0.1223	0.056*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.048 (2)	0.0257 (16)	0.0158 (15)	−0.0051 (14)	0.0024 (13)	−0.0091 (12)
O2	0.058 (2)	0.0340 (18)	0.0220 (17)	−0.0101 (16)	0.0045 (15)	−0.0136 (14)
O3	0.075 (3)	0.0332 (19)	0.0191 (17)	−0.0023 (17)	−0.0025 (16)	−0.0135 (14)
O4	0.055 (2)	0.0313 (17)	0.0167 (16)	−0.0054 (16)	0.0010 (14)	−0.0057 (13)
C1	0.039 (3)	0.031 (2)	0.014 (2)	−0.009 (2)	0.0021 (18)	−0.0073 (18)
C2	0.039 (3)	0.031 (2)	0.021 (2)	−0.008 (2)	−0.001 (2)	−0.0036 (19)
C3	0.024 (2)	0.024 (2)	0.024 (2)	−0.0048 (18)	0.0008 (17)	−0.0061 (17)
C4	0.019 (2)	0.030 (2)	0.022 (2)	−0.0075 (18)	0.0028 (17)	−0.0098 (19)
C5	0.026 (3)	0.018 (2)	0.027 (2)	−0.0034 (17)	0.0025 (18)	−0.0096 (18)
C6	0.027 (3)	0.034 (2)	0.022 (2)	−0.005 (2)	0.0029 (18)	−0.0140 (19)
C7	0.027 (3)	0.030 (2)	0.016 (2)	−0.0054 (19)	0.0024 (17)	−0.0073 (17)
C8	0.031 (3)	0.024 (2)	0.022 (2)	−0.0058 (19)	0.0035 (18)	−0.0086 (18)
C9	0.024 (2)	0.022 (2)	0.021 (2)	−0.0031 (17)	0.0014 (17)	−0.0102 (17)
C10	0.045 (3)	0.029 (3)	0.030 (3)	−0.007 (2)	0.006 (2)	−0.007 (2)

Geometric parameters (Å, º)

O1—C1	1.363 (5)	C4—C9	1.372 (6)
O1—C9	1.382 (5)	C4—C5	1.407 (5)
O2—C1	1.233 (5)	C5—C6	1.369 (6)
O3—C6	1.362 (5)	C5—H5	0.9300
O3—H3	0.8200	C6—C7	1.398 (6)
O4—C7	1.361 (5)	C7—C8	1.373 (6)
O4—H4	0.8200	C8—C9	1.384 (6)
C1—C2	1.415 (6)	C8—H8	0.9300
C2—C3	1.354 (6)	C10—H10A	0.9600
C2—H2	0.9300	C10—H10B	0.9600
C3—C4	1.446 (6)	C10—H10C	0.9600
C3—C10	1.490 (6)
C1—O1—C9	121.1 (3)	O3—C6—C5	118.7 (4)
C6—O3—H3	109.5	O3—C6—C7	121.6 (4)
C7—O4—H4	109.5	C5—C6—C7	119.8 (4)
O2—C1—O1	114.5 (4)	O4—C7—C8	122.5 (4)
O2—C1—C2	128.1 (4)	O4—C7—C6	117.3 (4)
O1—C1—C2	117.4 (4)	C8—C7—C6	120.1 (4)
C3—C2—C1	123.0 (4)	C7—C8—C9	118.7 (4)
C3—C2—H2	118.5	C7—C8—H8	120.7
C1—C2—H2	118.5	C9—C8—H8	120.7
C2—C3—C4	118.3 (4)	C4—C9—O1	121.8 (4)
C2—C3—C10	120.8 (4)	C4—C9—C8	123.2 (4)
C4—C3—C10	120.9 (4)	O1—C9—C8	115.0 (3)
C9—C4—C5	116.8 (4)	C3—C10—H10A	109.5
C9—C4—C3	118.1 (4)	C3—C10—H10B	109.5
C5—C4—C3	125.1 (4)	H10A—C10—H10B	109.5
C6—C5—C4	121.3 (4)	C3—C10—H10C	109.5
C6—C5—H5	119.3	H10A—C10—H10C	109.5
C4—C5—H5	119.3	H10B—C10—H10C	109.5
C9—O1—C1—O2	174.3 (4)	O3—C6—C7—O4	0.3 (7)
C9—O1—C1—C2	−6.9 (6)	C5—C6—C7—O4	178.7 (4)
O2—C1—C2—C3	−176.9 (5)	O3—C6—C7—C8	−180.0 (4)
O1—C1—C2—C3	4.4 (7)	C5—C6—C7—C8	−1.6 (7)
C1—C2—C3—C4	−0.5 (7)	O4—C7—C8—C9	−177.9 (4)
C1—C2—C3—C10	179.1 (4)	C6—C7—C8—C9	2.4 (7)
C2—C3—C4—C9	−1.0 (6)	C5—C4—C9—O1	−179.0 (4)
C10—C3—C4—C9	179.4 (4)	C3—C4—C9—O1	−1.5 (6)
C2—C3—C4—C5	176.3 (4)	C5—C4—C9—C8	1.4 (6)
C10—C3—C4—C5	−3.2 (7)	C3—C4—C9—C8	179.0 (4)
C9—C4—C5—C6	−0.5 (6)	C1—O1—C9—C4	5.6 (6)
C3—C4—C5—C6	−177.9 (4)	C1—O1—C9—C8	−174.8 (4)
C4—C5—C6—O3	179.1 (4)	C7—C8—C9—C4	−2.4 (7)
C4—C5—C6—C7	0.6 (7)	C7—C8—C9—O1	178.0 (4)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3···O4	0.82	2.30	2.737 (4)	114
O3—H3···O2^i	0.82	2.02	2.770 (4)	152
O4—H4···O2^ii	0.82	2.10	2.917 (4)	173
C8—H8···O1^ii	0.93	2.32	3.160 (5)	150

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