Redetermination of 7,8-dihydr­oxy-2H-chromen-2-one hemihydrate

The skeleton of the title compound, C₉H₆O₄·0.5H₂O, with the water mol­ecule located on a twofold rotation axis, consists of a coumarin that is composed of a benzene ring and a lactone ring. The hydroxyl groups, carbonyl group and water form inter­molecular O—H...O hydrogen bonds, which link the mol­ecules and solvent water into a three-dimensional network. An error in the position of an H atom in the original report is corrected.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.043
• wR factor = 0.110
• Data-to-parameter ratio = 8.0

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings    Differ ....          ?
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT045_ALERT_1_C Calculated and Reported Z Differ by ............       0.50 Ratio

Alert level G
REFLT03_ALERT_1_G ALERT: Expected hkl max differ from CIF values
           From the CIF: _diffrn_reflns_theta_max           27.99
           From the CIF: _reflns_number_total               1066
           From the CIF: _diffrn_reflns_limit_ max hkl   30.   46.    4.
           From the CIF: _diffrn_reflns_limit_ min hkl  -30.  -46.   -4.
           TEST1: Expected hkl limits for theta max
           Calculated maximum hkl   30.   48.    4.
           Calculated minimum hkl  -30.  -48.   -4.
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           27.99
           From the CIF: _reflns_number_total               1066
           Count of symmetry unique reflns         1082
           Completeness (_total/calc)             98.52%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured         0
           Fraction of Friedel pairs measured     0.000
           Are heavy atom types Z>Si present         no

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

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

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Computing details

Data collection: DENZO (Otwinowski & Minor, 1997); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97; molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97.

7,8-dihydroxy-2H-chromen-2-one hemihydrate

Crystal data

C9H6O4·0.5H2O	F(000) = 1552
Mr = 187.15	Dx = 1.592 Mg m^−3
Orthorhombic, Fdd2	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: F 2 -2d	Cell parameters from 1066 reflections
a = 22.990 (3) Å	θ = 2.8–28.0°
b = 36.609 (5) Å	µ = 0.13 mm^−1
c = 3.711 (3) Å	T = 298 K
V = 3123 (3) Å^3	Prism, pale yellow
Z = 16	0.50 × 0.25 × 0.20 mm

Data collection

MAC DIP 2030K diffractometer	1048 reflections with I > 2σ(I)
Radiation source: rotating anode	Rint = 0.045
Graphite monochromator	θmax = 28.0°, θmin = 2.8°
Detector resolution: 0 pixels mm^-1	h = −30→30
ω scans	k = −46→46
3924 measured reflections	l = −4→4
1066 independent reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.043	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.110	w = 1/[σ^2(Fo^2) + (0.0719P)^2 + 2.386P] where P = (Fo^2 + 2Fc^2)/3
S = 1.08	(Δ/σ)max < 0.001
1066 reflections	Δρmax = 0.20 e Å^−3
133 parameters	Δρmin = −0.22 e Å^−3
1 restraint	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.049 (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
O5	0.0000	0.0000	0.7104 (8)	0.0431 (6)
H5O	−0.0212 (13)	0.0088 (9)	0.825 (13)	0.065*
O1	0.10359 (6)	0.11936 (3)	0.2266 (5)	0.0368 (4)
O2	0.10086 (7)	0.17879 (4)	0.2818 (7)	0.0549 (6)
O3	0.09718 (6)	−0.00845 (4)	0.1731 (6)	0.0442 (5)
H3O	0.1200 (13)	−0.0270 (9)	0.106 (13)	0.066*
O4	0.04674 (6)	0.05747 (4)	0.3330 (6)	0.0409 (5)
H4O	0.0388 (12)	0.0383 (9)	0.421 (12)	0.061*
C2	0.12970 (8)	0.15254 (5)	0.1830 (7)	0.0391 (5)
C3	0.18754 (9)	0.15346 (6)	0.0326 (8)	0.0451 (6)
H3	0.2057	0.1758	−0.0047	0.054*
C4	0.21558 (8)	0.12261 (6)	−0.0541 (7)	0.0418 (5)
H4	0.2530	0.1239	−0.1485	0.050*
C4A	0.18852 (8)	0.08766 (5)	−0.0031 (6)	0.0333 (5)
C5	0.21528 (8)	0.05426 (6)	−0.0825 (7)	0.0386 (5)
H5	0.2531	0.0538	−0.1718	0.046*
C6	0.18550 (8)	0.02200 (5)	−0.0279 (7)	0.0382 (5)
H6	0.2029	−0.0002	−0.0854	0.046*
C7	0.12921 (8)	0.02264 (5)	0.1135 (6)	0.0332 (5)
C8	0.10157 (8)	0.05534 (5)	0.2000 (7)	0.0322 (5)
C8A	0.13243 (8)	0.08720 (4)	0.1380 (6)	0.0315 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O5	0.0362 (10)	0.0337 (10)	0.0593 (15)	−0.0015 (7)	0.000	0.000
O1	0.0346 (6)	0.0233 (6)	0.0525 (10)	−0.0005 (4)	0.0088 (7)	−0.0031 (6)
O2	0.0510 (8)	0.0274 (7)	0.0864 (16)	−0.0045 (5)	0.0161 (10)	−0.0089 (9)
O3	0.0433 (7)	0.0249 (6)	0.0643 (12)	0.0038 (5)	0.0048 (8)	−0.0026 (7)
O4	0.0329 (7)	0.0254 (6)	0.0644 (11)	0.0003 (4)	0.0112 (8)	0.0023 (7)
C2	0.0397 (9)	0.0235 (8)	0.0540 (14)	−0.0068 (6)	0.0043 (10)	−0.0027 (9)
C3	0.0380 (9)	0.0372 (9)	0.0602 (15)	−0.0121 (7)	0.0123 (11)	0.0002 (10)
C4	0.0317 (8)	0.0457 (10)	0.0480 (13)	−0.0053 (7)	0.0062 (9)	−0.0018 (10)
C4A	0.0261 (7)	0.0390 (9)	0.0347 (11)	−0.0013 (6)	0.0024 (8)	−0.0031 (8)
C5	0.0288 (8)	0.0446 (10)	0.0423 (12)	0.0069 (7)	0.0043 (9)	−0.0020 (10)
C6	0.0332 (8)	0.0361 (9)	0.0454 (13)	0.0111 (7)	−0.0002 (9)	−0.0050 (10)
C7	0.0329 (8)	0.0273 (8)	0.0394 (11)	0.0019 (6)	−0.0009 (9)	−0.0007 (8)
C8	0.0318 (8)	0.0263 (8)	0.0385 (11)	0.0015 (6)	−0.0001 (8)	−0.0011 (8)
C8A	0.0289 (8)	0.0273 (8)	0.0382 (11)	0.0024 (6)	0.0011 (8)	−0.0040 (8)

Geometric parameters (Å, º)

O5—H5O	0.72 (4)	C4—C4A	1.435 (3)
O1—C2	1.364 (2)	C4—H4	0.9300
O1—C8A	1.3908 (19)	C4A—C8A	1.392 (3)
O2—C2	1.224 (3)	C4A—C5	1.400 (3)
O3—C7	1.373 (2)	C5—C6	1.380 (3)
O3—H3O	0.89 (3)	C5—H5	0.9300
O4—C8	1.356 (2)	C6—C7	1.397 (3)
O4—H4O	0.80 (4)	C6—H6	0.9300
C2—C3	1.443 (3)	C7—C8	1.393 (2)
C3—C4	1.340 (3)	C8—C8A	1.384 (2)
C3—H3	0.9300
C2—O1—C8A	121.06 (15)	C6—C5—C4A	119.91 (18)
C7—O3—H3O	106 (2)	C6—C5—H5	120.0
C8—O4—H4O	108 (2)	C4A—C5—H5	120.0
O2—C2—O1	115.17 (18)	C5—C6—C7	120.02 (17)
O2—C2—C3	126.65 (17)	C5—C6—H6	120.0
O1—C2—C3	118.18 (17)	C7—C6—H6	120.0
C4—C3—C2	121.11 (18)	O3—C7—C8	115.51 (16)
C4—C3—H3	119.4	O3—C7—C6	122.91 (16)
C2—C3—H3	119.4	C8—C7—C6	121.58 (17)
C3—C4—C4A	120.76 (18)	O4—C8—C8A	119.24 (15)
C3—C4—H4	119.6	O4—C8—C7	123.87 (16)
C4A—C4—H4	119.6	C8A—C8—C7	116.88 (17)
C8A—C4A—C5	118.40 (17)	C8—C8A—O1	115.45 (15)
C8A—C4A—C4	117.52 (16)	C8—C8A—C4A	123.20 (16)
C5—C4A—C4	124.08 (18)	O1—C8A—C4A	121.35 (15)
C8A—O1—C2—O2	−177.6 (2)	C6—C7—C8—O4	179.0 (2)
C8A—O1—C2—C3	1.7 (4)	O3—C7—C8—C8A	−179.1 (2)
O2—C2—C3—C4	177.6 (3)	C6—C7—C8—C8A	0.2 (3)
O1—C2—C3—C4	−1.6 (4)	O4—C8—C8A—O1	1.0 (3)
C2—C3—C4—C4A	0.6 (4)	C7—C8—C8A—O1	179.9 (2)
C3—C4—C4A—C8A	0.2 (4)	O4—C8—C8A—C4A	−179.0 (2)
C3—C4—C4A—C5	−179.1 (2)	C7—C8—C8A—C4A	−0.1 (3)
C8A—C4A—C5—C6	1.5 (3)	C2—O1—C8A—C8	179.0 (2)
C4—C4A—C5—C6	−179.3 (2)	C2—O1—C8A—C4A	−1.0 (3)
C4A—C5—C6—C7	−1.4 (4)	C5—C4A—C8A—C8	−0.7 (3)
C5—C6—C7—O3	179.8 (2)	C4—C4A—C8A—C8	180.0 (2)
C5—C6—C7—C8	0.5 (4)	C5—C4A—C8A—O1	179.3 (2)
O3—C7—C8—O4	−0.3 (4)	C4—C4A—C8A—O1	0.0 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O5—H5O···O3^i	0.72 (4)	2.17 (4)	2.835 (2)	153 (4)
O3—H3O···O2^ii	0.89 (3)	1.77 (3)	2.642 (2)	163 (3)
O4—H4O···O5	0.80 (4)	1.98 (4)	2.746 (2)	162 (3)

Symmetry codes: (i) −x, −y, z+1; (ii) −x+1/4, y−1/4, z−1/4.