3H-Furo[3,4-c]isochromene-1,5-dione

The title compound, C₁₁H₆O₄, is a synthetic isocoumarin and is essentially planar.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.034
• wR factor = 0.096
• Data-to-parameter ratio = 10.2

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT031_ALERT_4_B Refined Extinction Parameter within Range ......       2.00 Sigma
PLAT230_ALERT_2_B Hirshfeld Test Diff for    O3     -   C10     ..       7.21 su

Alert level C
ABSTM02_ALERT_3_C  The ratio of expected to reported Tmax/Tmin(RR') is < 0.90
            Tmin and Tmax reported:      0.850     1.000
            Tmin(prime) and Tmax expected:      0.962     0.976
            RR(prime) =      0.863
            Please check that your absorption correction is appropriate.
REFLT03_ALERT_3_C  Reflection count < 95% complete
           From the CIF: _diffrn_reflns_theta_max           24.99
           From the CIF: _diffrn_reflns_theta_full          27.99
           From the CIF: _reflns_number_total               1396
           TEST2: Reflns within _diffrn_reflns_theta_max
           Count of symmetry unique reflns         1529
           Completeness (_total/calc)             91.30%
PLAT022_ALERT_3_C Ratio Unique / Expected Reflections too Low ....       0.91
PLAT061_ALERT_3_C Tmax/Tmin Range Test RR' too Large .............       0.86
PLAT062_ALERT_4_C Rescale T(min) & T(max) by .....................       0.98

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K

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

   2 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
   2 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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Computing details

Data collection: SMART (Bruker, 1999 or 2000); cell refinement: SAINT (Bruker, 1999 or 2000); data reduction: SAINT; 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, PARST (Nardelli, 1995) and PLATON (Spek, 2003).

3H-furo[3,4-c]isochromene-1,5-dione

Crystal data

C11H6O4	Z = 2
Mr = 202.16	F(000) = 208
Triclinic, P1	Dx = 1.552 Mg m^−3
Hall symbol: -P 1	Melting point: 131 K
a = 7.9892 (13) Å	Mo Kα radiation, λ = 0.71073 Å
b = 8.0899 (13) Å	Cell parameters from 1966 reflections
c = 8.2075 (13) Å	θ = 2.7–28.0°
α = 67.089 (3)°	µ = 0.12 mm^−1
β = 83.871 (3)°	T = 293 K
γ = 62.738 (3)°	Block, pale yellow
V = 432.68 (12) Å^3	0.32 × 0.24 × 0.20 mm

Data collection

Bruker SMART CCD diffractometer	1396 independent reflections
Radiation source: fine-focus sealed tube	1105 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.015
ω and φ scans	θmax = 25.0°, θmin = 2.7°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −5→9
Tmin = 0.850, Tmax = 1.000	k = −9→9
1966 measured reflections	l = −8→9

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)] = 0.034	H-atom parameters constrained
wR(F^2) = 0.096	w = 1/[σ^2(Fo^2) + (0.0511P)^2 + 0.0519P] where P = (Fo^2 + 2Fc^2)/3
S = 1.03	(Δ/σ)max < 0.001
1396 reflections	Δρmax = 0.13 e Å^−3
137 parameters	Δρmin = −0.13 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.010 (5)

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
C1	−0.0669 (2)	0.5585 (3)	0.1830 (2)	0.0475 (4)
H1A	0.0041	0.6173	0.1091	0.057*
C2	−0.2553 (3)	0.6331 (3)	0.1358 (2)	0.0523 (4)
H2A	−0.3115	0.7425	0.0295	0.063*
C3	−0.3619 (2)	0.5468 (3)	0.2451 (2)	0.0500 (4)
H3A	−0.4893	0.5993	0.2116	0.060*
C4	−0.2822 (2)	0.3843 (3)	0.4029 (2)	0.0441 (4)
H4A	−0.3549	0.3268	0.4751	0.053*
C5	−0.0901 (2)	0.3059 (2)	0.4539 (2)	0.0381 (4)
C6	0.0168 (2)	0.3949 (2)	0.3418 (2)	0.0413 (4)
C7	0.2199 (2)	0.3161 (3)	0.3874 (2)	0.0485 (4)
C8	0.1921 (2)	0.0762 (3)	0.6536 (2)	0.0450 (4)
C9	0.0101 (2)	0.1379 (2)	0.6160 (2)	0.0410 (4)
C10	−0.0490 (3)	0.0089 (3)	0.7637 (2)	0.0474 (4)
C11	0.2657 (3)	−0.0938 (3)	0.8286 (3)	0.0565 (5)
H11A	0.3693	−0.2122	0.8168	0.068*
H11B	0.3078	−0.0576	0.9103	0.068*
O1	0.32400 (19)	0.3771 (2)	0.2990 (2)	0.0691 (4)
O2	0.30184 (15)	0.15428 (19)	0.55065 (16)	0.0529 (3)
O3	−0.20040 (18)	0.0079 (2)	0.78669 (17)	0.0627 (4)
O4	0.10321 (17)	−0.12689 (18)	0.88611 (15)	0.0589 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0603 (10)	0.0516 (10)	0.0432 (9)	−0.0369 (8)	0.0171 (7)	−0.0197 (8)
C2	0.0621 (11)	0.0491 (10)	0.0450 (9)	−0.0290 (9)	0.0041 (8)	−0.0127 (8)
C3	0.0446 (9)	0.0522 (10)	0.0522 (10)	−0.0228 (8)	0.0027 (7)	−0.0179 (8)
C4	0.0436 (9)	0.0485 (9)	0.0479 (9)	−0.0274 (7)	0.0129 (7)	−0.0201 (8)
C5	0.0451 (9)	0.0391 (8)	0.0380 (8)	−0.0232 (7)	0.0111 (6)	−0.0195 (7)
C6	0.0471 (9)	0.0482 (9)	0.0450 (9)	−0.0302 (7)	0.0158 (7)	−0.0263 (8)
C7	0.0504 (9)	0.0591 (10)	0.0531 (10)	−0.0349 (8)	0.0163 (8)	−0.0289 (9)
C8	0.0455 (9)	0.0486 (9)	0.0477 (9)	−0.0228 (7)	0.0095 (7)	−0.0248 (8)
C9	0.0452 (9)	0.0422 (9)	0.0424 (9)	−0.0235 (7)	0.0125 (7)	−0.0206 (7)
C10	0.0584 (10)	0.0404 (9)	0.0421 (9)	−0.0226 (8)	0.0123 (8)	−0.0164 (7)
C11	0.0546 (10)	0.0530 (10)	0.0537 (10)	−0.0176 (8)	−0.0004 (8)	−0.0198 (8)
O1	0.0581 (8)	0.0907 (11)	0.0776 (9)	−0.0539 (8)	0.0258 (7)	−0.0314 (8)
O2	0.0422 (6)	0.0641 (8)	0.0582 (7)	−0.0280 (6)	0.0077 (5)	−0.0253 (6)
O3	0.0628 (8)	0.0639 (8)	0.0607 (8)	−0.0396 (7)	0.0217 (6)	−0.0142 (6)
O4	0.0642 (8)	0.0511 (8)	0.0483 (7)	−0.0240 (6)	0.0077 (6)	−0.0101 (6)

Geometric parameters (Å, º)

C1—C2	1.375 (3)	C7—O1	1.196 (2)
C1—C6	1.389 (2)	C7—O2	1.405 (2)
C1—H1A	0.9300	C8—C9	1.330 (2)
C2—C3	1.382 (2)	C8—O2	1.348 (2)
C2—H2A	0.9300	C8—C11	1.484 (3)
C3—C4	1.376 (2)	C9—C10	1.458 (2)
C3—H3A	0.9300	C10—O3	1.207 (2)
C4—C5	1.404 (2)	C10—O4	1.369 (2)
C4—H4A	0.9300	C11—O4	1.438 (2)
C5—C6	1.405 (2)	C11—H11A	0.9700
C5—C9	1.443 (2)	C11—H11B	0.9700
C6—C7	1.476 (2)
C2—C1—C6	119.60 (15)	O1—C7—C6	126.40 (18)
C2—C1—H1A	120.2	O2—C7—C6	117.88 (14)
C6—C1—H1A	120.2	C9—C8—O2	126.12 (16)
C1—C2—C3	120.55 (16)	C9—C8—C11	111.79 (15)
C1—C2—H2A	119.7	O2—C8—C11	122.09 (15)
C3—C2—H2A	119.7	C8—C9—C5	120.58 (15)
C4—C3—C2	120.93 (16)	C8—C9—C10	106.99 (15)
C4—C3—H3A	119.5	C5—C9—C10	132.42 (14)
C2—C3—H3A	119.5	O3—C10—O4	121.26 (16)
C3—C4—C5	119.49 (15)	O3—C10—C9	130.45 (17)
C3—C4—H4A	120.3	O4—C10—C9	108.29 (14)
C5—C4—H4A	120.3	O4—C11—C8	102.36 (14)
C4—C5—C6	119.07 (15)	O4—C11—H11A	111.3
C4—C5—C9	125.06 (14)	C8—C11—H11A	111.3
C6—C5—C9	115.88 (14)	O4—C11—H11B	111.3
C1—C6—C5	120.36 (15)	C8—C11—H11B	111.3
C1—C6—C7	118.36 (15)	H11A—C11—H11B	109.2
C5—C6—C7	121.28 (16)	C8—O2—C7	118.22 (13)
O1—C7—O2	115.72 (15)	C10—O4—C11	110.55 (13)
C6—C1—C2—C3	0.1 (3)	C11—C8—C9—C10	−1.10 (19)
C1—C2—C3—C4	−0.3 (3)	C4—C5—C9—C8	−179.15 (15)
C2—C3—C4—C5	0.4 (2)	C6—C5—C9—C8	0.6 (2)
C3—C4—C5—C6	−0.3 (2)	C4—C5—C9—C10	0.0 (3)
C3—C4—C5—C9	179.36 (15)	C6—C5—C9—C10	179.72 (15)
C2—C1—C6—C5	−0.1 (2)	C8—C9—C10—O3	−179.29 (18)
C2—C1—C6—C7	179.00 (14)	C5—C9—C10—O3	1.5 (3)
C4—C5—C6—C1	0.2 (2)	C8—C9—C10—O4	0.20 (17)
C9—C5—C6—C1	−179.52 (14)	C5—C9—C10—O4	−179.05 (15)
C4—C5—C6—C7	−178.86 (14)	C9—C8—C11—O4	1.52 (19)
C9—C5—C6—C7	1.4 (2)	O2—C8—C11—O4	−178.89 (13)
C1—C6—C7—O1	−1.4 (3)	C9—C8—O2—C7	−0.1 (2)
C5—C6—C7—O1	177.69 (16)	C11—C8—O2—C7	−179.61 (15)
C1—C6—C7—O2	178.18 (13)	O1—C7—O2—C8	−178.34 (14)
C5—C6—C7—O2	−2.7 (2)	C6—C7—O2—C8	2.0 (2)
O2—C8—C9—C5	−1.3 (2)	O3—C10—O4—C11	−179.66 (16)
C11—C8—C9—C5	178.26 (14)	C9—C10—O4—C11	0.79 (17)
O2—C8—C9—C10	179.34 (15)	C8—C11—O4—C10	−1.35 (17)