A new polymorph of 9,10-di­hydro­anthracene-9,10-α,β-succinic acid anhydride

Díaz de Delgado, G.; Ramírez V, B.; Velásquez, W.; Rodríguez, P.

doi:10.1107/S1600536802005767

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A new polymorph of 9,10-dihydroanthracene-9,10-α,β-succinic acid anhydride

G. Díaz de Delgado, B. Ramírez V, W. Velásquez and P. Rodríguez

A new non-centrosymmetric monoclinic modification of 9,10-dihydroanthracene-9,10-α,β-succinic acid anhydride (systematic name: 5,6:7,8-dibenzobicyclo[2.2.2]octa-5,7-diene-2,3-dicarboxylic acid anhydride), C₁₈H₁₂O₃, was obtained by reacting maleic anhydride and anthracene in xylene, followed by recrystallization from ethyl acetate. The structure consists of chains of molecules along the c axis and is held together solely through van der Waals interactions.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536802005767/bt6131sup1.cif Contains datablocks global, I
	Structure factor file (CIF format) https://doi.org/10.1107/S1600536802005767/bt6131Isup2.hkl Contains datablock I

CCDC reference: 185775

checkCIF report

Key indicators

Single-crystal X-ray study
T = 293 K
Mean (C-C) = 0.004 Å
R factor = 0.036
wR factor = 0.084
Data-to-parameter ratio = 8.1

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



REFLT_03
         From the CIF: _diffrn_reflns_theta_max           28.31
         From the CIF: _reflns_number_total               1543
         TEST2: Reflns within _diffrn_reflns_theta_max
         Count of symmetry unique reflns         1653
         Completeness (_total/calc)             93.35%
          Alert C: < 95% complete

General Notes



REFLT_03
         From the CIF: _diffrn_reflns_theta_max           28.31
         From the CIF: _reflns_number_total               1543
         Count of symmetry unique reflns         1653
         Completeness (_total/calc)             93.35%
         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
          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.


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 1 Alert Level C = Please check

Comment top

As part of a project on Diels–Alder reactions in an undergraduate organic chemistry laboratory, 9,10-dihydroanthracene-9,10-α,β-succinic acid anhydride, (I), was synthesized. The compound had been previously prepared (Bulgarovskii et al., 1979) and the crystal data and coordinates are reported in the Cambridge Structural Database (refcode BCOCAN; Allen & Kennard, 1993). Bulgarovskii et al. used benzene as the reaction and crystallization solvent, while in the present study, xylene was used for the reaction and the material was recrystallized from ethyl acetate. The reported unit-cell parameters for BCOCAN are a = 11.229 (3), b = 12.874 (3), c = 9.468 (4) Å and γ = 103.51 (2)° (space group P2₁/b). The cell in (I) and the cell obtained by Bulgarovskii et al., (II), are related, approximately, by the transformation a_II = [001/101/010]a_I. The frames collected were re-indexed in cell (II) and attempts were made to solve the structure in this cell but without success. Therefore, it was considered appropriate to describe the material under investigation as a new polymorph.

In the structure of BCOCAN, pairs of molecules related by the 2₁ axis face each other in an antiparallel fashion and have the planes of the anhydride rings parallel to the b axis. The central O atom of these rings points approximately in the +c and -c directions.

In contrast, as shown in Fig. 2, in the Cc polymorph, the molecules pack in chains along the c axis, with the planes of the anhydride rings approximately parallel to the b axis. The central O atoms of the anhydride rings point in the [11] and [110] directions.

In both cases, van der Waals interactions are responsible of the interactions between the molecules.

Experimental top

The title compound was prepared by mixing maleic anhydride (dienophile) and anthracene (diene) in xylene in a 1:1 molar ratio. The mixture was refluxed at 403–413 K for 35 min. The resulting solution was allowed to cool to room temperature and was then placed in a water–ice bath. The yellow crystals formed were removed by filtration and washed with ethyl acetate. They were recrystallized from hot ethyl acetate, using activated charcoal to remove impurities. Colourless crystals formed upon cooling the ethyl acetate solution. The IR spectra were recorded from KBr discs, using a PE-1600 FTIR spectrometer with IRDM software. IR (cm^-1): ν(δb C—H asymmetric) 3075, ν(═C—H symmetric) 3026, ν(C—H) 2968, ν(C═O asymmetric) 1862, ν(C═O symmetric) 1782, ν(C═C) 1463, ν(C—O asymmetric) 1229, ν(C—O symmetric) 1069. The ¹H and ¹³C NMR spectra were obtained on a Bruker Advance 400 equipment. ¹H NMR (400 MHz, CDCl₃, M₄Si; δ_H, p.p.m.): 3.55 (2H, s), 4.87 (2H, s), 7.34 (4H, m), 7.41 (4H, m). ¹³C NMR: (400 MHz, CDCl₃, M₄Si, δ_H, p.p.m.): 170.42 (C1, C2), 140.62 (C7, C12), 138.09 (C13, C18), 127.75 (C8, C11), 127.14 (C9,C10), 125.20 (C14,C17), 125.20 (C15,C16), 47.98 (C3, C4), 45.41 (C5, C6).

Computing details top

Data collection: SMART (Bruker, 1997-1998); cell refinement: SAINT (Bruker, 1997-1998; data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 1998); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 1990).

Figures top

	Fig. 1. PLEASE SUPPLY CAPTION
	Fig. 2. PLEASE SUPPLY CAPTION

5,6:7,8-dibenzobicyclo[2.2.2]octa-5,7-diene-2,3-dicarboxylic acid anhydride top

Crystal data top

C₁₈H₁₂O₃	F(000) = 576
M_r = 276.28	D_x = 1.381 Mg m⁻³
Monoclinic, Cc	Melting point: 261.3(1)° K
Hall symbol: C -2yc	Mo Kα radiation, λ = 0.71073 Å
a = 15.410 (2) Å	Cell parameters from 1961 reflections
b = 9.4020 (12) Å	θ = 2.7–28.3°
c = 11.0939 (15) Å	µ = 0.09 mm⁻¹
β = 124.235 (10)°	T = 293 K
V = 1328.8 (3) Å³	Prism, colorless
Z = 4	0.6 × 0.4 × 0.32 mm

Data collection top

Bruker SMART CCD area-detector diffractometer	1289 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.035
Graphite monochromator	θ_max = 28.3°, θ_min = 2.7°
Detector resolution: 0.75 pixels mm^-1	h = −19→18
ϕ and ω scans	k = −7→12
8380 measured reflections	l = −14→14
1543 independent reflections

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)] = 0.036	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.084	H-atom parameters constrained
S = 1.03	w = 1/[σ²(F_o²) + (0.0507P)²] where P = (F_o² + 2F_c²)/3
1543 reflections	(Δ/σ)_max < 0.001
190 parameters	Δρ_max = 0.12 e Å⁻³
2 restraints	Δρ_min = −0.16 e Å⁻³

Crystal data top

C₁₈H₁₂O₃	V = 1328.8 (3) Å³
M_r = 276.28	Z = 4
Monoclinic, Cc	Mo Kα radiation
a = 15.410 (2) Å	µ = 0.09 mm⁻¹
b = 9.4020 (12) Å	T = 293 K
c = 11.0939 (15) Å	0.6 × 0.4 × 0.32 mm
β = 124.235 (10)°

Data collection top

Bruker SMART CCD area-detector diffractometer	1289 reflections with I > 2σ(I)
8380 measured reflections	R_int = 0.035
1543 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.036	2 restraints
wR(F²) = 0.084	H-atom parameters constrained
S = 1.03	Δρ_max = 0.12 e Å⁻³
1543 reflections	Δρ_min = −0.16 e Å⁻³
190 parameters

Special details top

Experimental. Siemens SMART CCD diffractometer equipped with a normal focus, 2.4 kW sealed tube X-ray source (Mo Kα radiation, λ = 0.71073 Å) operating at 40 kV and 35 mA. The data collection covered about 1.3 hemisphere of reciprocal space by a combination of three sets of exposures; each set had a different ϕ angle (0, 90, 180 °) for the crystal and each exposure of 10 s covered 0.3° in ω to give a total of 1321 frames. The crystal-to-detector distance was 5.029 cm and the detector swing angle was -30°. Coverage of the unique set was over 99% complete. Crystal decay was monitored by repeating fifty frames from the initial set at the end of the data collection. The analysis of the duplicate reflections indicated that crystal decay was negligible.

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All e.s.d.'s are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

Refinement. Refinement on F² for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The observed criterion of F² > σ(F²) is used only for calculating -R-factor-obs 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
O1	0.39685 (17)	0.8228 (2)	0.6917 (2)	0.0847 (7)
O2	0.27881 (16)	0.66074 (19)	0.5445 (2)	0.0694 (7)
O3	0.1388 (2)	0.5462 (2)	0.3630 (3)	0.0962 (9)
C1	0.3132 (2)	0.7995 (3)	0.5837 (3)	0.0573 (9)
C2	0.1805 (2)	0.6570 (3)	0.4147 (3)	0.0623 (10)
C3	0.23194 (17)	0.9012 (2)	0.4725 (2)	0.0436 (6)
C4	0.14307 (17)	0.8055 (2)	0.3580 (2)	0.0459 (7)
C5	0.27666 (15)	0.9919 (2)	0.4012 (2)	0.0401 (6)
C6	0.12639 (15)	0.8282 (2)	0.2075 (2)	0.0431 (6)
C7	0.31173 (15)	0.8876 (2)	0.33241 (19)	0.0392 (6)
C8	0.41146 (17)	0.8754 (3)	0.3617 (2)	0.0501 (7)
C9	0.43059 (19)	0.7741 (3)	0.2895 (3)	0.0590 (8)
C10	0.3514 (2)	0.6849 (3)	0.1888 (3)	0.0593 (9)
C11	0.25095 (19)	0.6967 (3)	0.1576 (2)	0.0522 (8)
C12	0.23125 (15)	0.7989 (2)	0.2291 (2)	0.0402 (6)
C13	0.10372 (15)	0.9854 (2)	0.1736 (2)	0.0435 (6)
C14	0.01505 (17)	1.0439 (3)	0.0520 (2)	0.0557 (8)
C15	0.0080 (2)	1.1911 (3)	0.0349 (3)	0.0650 (9)
C16	0.0876 (2)	1.2770 (3)	0.1383 (3)	0.0626 (9)
C17	0.1758 (2)	1.2195 (2)	0.2607 (3)	0.0524 (8)
C18	0.18434 (15)	1.0732 (2)	0.2781 (2)	0.0417 (6)
H3	0.20670	0.96340	0.51750	0.0520*
H4	0.07810	0.82590	0.35130	0.0550*
H5	0.33360	1.05500	0.47160	0.0480*
H6	0.07010	0.76820	0.13130	0.0520*
H8	0.46510	0.93500	0.42960	0.0600*
H9	0.49740	0.76580	0.30870	0.0710*
H10	0.36540	0.61650	0.14140	0.0710*
H11	0.19760	0.63670	0.08970	0.0630*
H14	−0.03910	0.98570	−0.01730	0.0670*
H15	−0.05090	1.23150	−0.04700	0.0780*
H16	0.08190	1.37520	0.12570	0.0750*
H17	0.22890	1.27850	0.33080	0.0630*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0800 (13)	0.0934 (15)	0.0498 (10)	0.0190 (11)	0.0177 (10)	0.0147 (10)
O2	0.0925 (14)	0.0524 (11)	0.0678 (11)	0.0178 (9)	0.0479 (11)	0.0179 (8)
O3	0.130 (2)	0.0477 (11)	0.1142 (17)	−0.0140 (11)	0.0707 (16)	−0.0004 (11)
C1	0.0703 (16)	0.0626 (16)	0.0434 (12)	0.0130 (12)	0.0347 (13)	0.0105 (10)
C2	0.0875 (19)	0.0466 (14)	0.0715 (17)	−0.0001 (13)	0.0560 (16)	0.0044 (12)
C3	0.0536 (11)	0.0447 (11)	0.0366 (9)	0.0073 (10)	0.0279 (9)	0.0003 (9)
C4	0.0526 (12)	0.0453 (11)	0.0497 (12)	−0.0003 (9)	0.0347 (10)	0.0010 (9)
C5	0.0443 (10)	0.0359 (10)	0.0355 (9)	−0.0015 (8)	0.0196 (8)	−0.0023 (8)
C6	0.0427 (10)	0.0460 (12)	0.0397 (10)	−0.0072 (8)	0.0226 (9)	−0.0069 (8)
C7	0.0445 (10)	0.0384 (10)	0.0375 (10)	0.0033 (8)	0.0248 (9)	0.0046 (8)
C8	0.0459 (12)	0.0535 (13)	0.0504 (12)	0.0005 (9)	0.0268 (10)	0.0038 (10)
C9	0.0562 (13)	0.0707 (16)	0.0650 (14)	0.0140 (12)	0.0432 (12)	0.0104 (13)
C10	0.0754 (17)	0.0605 (15)	0.0610 (15)	0.0125 (12)	0.0500 (14)	−0.0015 (11)
C11	0.0677 (15)	0.0497 (13)	0.0472 (12)	−0.0026 (10)	0.0372 (12)	−0.0065 (10)
C12	0.0455 (11)	0.0428 (10)	0.0371 (10)	−0.0003 (8)	0.0261 (9)	−0.0004 (8)
C13	0.0442 (10)	0.0536 (12)	0.0383 (9)	0.0042 (9)	0.0266 (9)	0.0024 (9)
C14	0.0444 (12)	0.0843 (18)	0.0382 (11)	0.0133 (11)	0.0231 (10)	0.0045 (11)
C15	0.0684 (16)	0.0870 (19)	0.0488 (13)	0.0391 (14)	0.0386 (13)	0.0258 (13)
C16	0.0810 (18)	0.0569 (15)	0.0664 (15)	0.0268 (13)	0.0515 (15)	0.0199 (13)
C17	0.0674 (14)	0.0434 (12)	0.0584 (13)	0.0092 (11)	0.0427 (12)	0.0053 (11)
C18	0.0479 (11)	0.0445 (11)	0.0405 (10)	0.0057 (9)	0.0296 (9)	0.0036 (9)

Geometric parameters (Å, º) top

O1—C1	1.186 (4)	C13—C14	1.384 (3)
O2—C1	1.383 (3)	C13—C18	1.396 (3)
O2—C2	1.384 (4)	C14—C15	1.393 (4)
O3—C2	1.188 (4)	C15—C16	1.375 (4)
C1—C3	1.505 (4)	C16—C17	1.381 (4)
C2—C4	1.506 (3)	C17—C18	1.385 (3)
C3—C4	1.530 (3)	C3—H3	0.9803
C3—C5	1.562 (3)	C4—H4	0.9803
C4—C6	1.554 (3)	C5—H5	0.9802
C5—C7	1.517 (3)	C6—H6	0.9799
C5—C18	1.512 (3)	C8—H8	0.9296
C6—C12	1.519 (4)	C9—H9	0.9299
C6—C13	1.517 (3)	C10—H10	0.9297
C7—C8	1.385 (4)	C11—H11	0.9299
C7—C12	1.396 (3)	C14—H14	0.9300
C8—C9	1.379 (4)	C15—H15	0.9304
C9—C10	1.381 (4)	C16—H16	0.9305
C10—C11	1.388 (5)	C17—H17	0.9306
C11—C12	1.384 (3)

O1···C8ⁱ	3.344 (3)	C16···O3^ix	3.321 (4)
O1···C15ⁱⁱ	3.410 (3)	C8···H6ⁱⁱⁱ	2.9185
O1···C4ⁱⁱⁱ	3.373 (4)	C13···H3^vii	2.9734
O2···C7	3.418 (3)	C14···H10^x	3.0563
O2···C12	3.403 (3)	C15···H4^vii	2.7959
O3···C16^iv	3.321 (4)	C16···H9^x	2.9109
O1···H4ⁱⁱⁱ	2.7067	H3···C13ⁱ	2.9734
O1···H15ⁱⁱ	2.6762	H4···C15ⁱ	2.7959
O2···H10^v	2.8490	H4···O1^vi	2.7067
O3···H16^iv	2.7725	H5···H8	2.5805
O3···H11^v	2.7458	H5···H17	2.5735
C1···C12	3.388 (3)	H6···H11	2.5734
C2···C7	3.421 (4)	H6···H14	2.5710
C2···C11	3.597 (4)	H6···C8^vi	2.9185
C2···C16ⁱ	3.547 (5)	H8···H5	2.5805
C4···C15ⁱ	3.575 (4)	H8···H16^xi	2.5983
C4···O1^vi	3.373 (4)	H9···C16^xii	2.9109
C7···O2	3.418 (3)	H10···O2^xiii	2.8490
C7···C2	3.421 (4)	H10···C14^xii	3.0563
C8···O1^vii	3.344 (3)	H11···H6	2.5734
C11···C2	3.597 (4)	H11···O3^xiii	2.7458
C12···C1	3.388 (3)	H14···H6	2.5710
C12···O2	3.403 (3)	H15···O1^viii	2.6762
C15···C4^vii	3.575 (4)	H16···O3^ix	2.7725
C15···O1^viii	3.410 (3)	H16···H8^xiv	2.5983
C16···C2^vii	3.547 (5)	H17···H5	2.5735

C1—O2—C2	110.6 (2)	C15—C16—C17	120.9 (3)
O1—C1—O2	119.9 (3)	C16—C17—C18	119.3 (2)
O1—C1—C3	129.8 (3)	C5—C18—C13	113.37 (16)
O2—C1—C3	110.3 (2)	C5—C18—C17	126.5 (2)
O2—C2—O3	120.2 (3)	C13—C18—C17	120.1 (2)
O2—C2—C4	110.4 (2)	C1—C3—H3	110.31
O3—C2—C4	129.4 (3)	C4—C3—H3	110.32
C1—C3—C4	104.49 (17)	C5—C3—H3	110.28
C1—C3—C5	111.2 (2)	C2—C4—H4	110.35
C4—C3—C5	110.14 (16)	C3—C4—H4	110.29
C2—C4—C3	104.17 (18)	C6—C4—H4	110.31
C2—C4—C6	111.64 (19)	C3—C5—H5	112.27
C3—C4—C6	109.93 (19)	C7—C5—H5	112.31
C3—C5—C7	106.58 (16)	C18—C5—H5	112.29
C3—C5—C18	105.9 (2)	C4—C6—H6	112.26
C7—C5—C18	107.03 (15)	C12—C6—H6	112.23
C4—C6—C12	106.69 (17)	C13—C6—H6	112.24
C4—C6—C13	106.02 (16)	C7—C8—H8	120.24
C12—C6—C13	106.98 (19)	C9—C8—H8	120.26
C5—C7—C8	126.72 (19)	C8—C9—H9	119.73
C5—C7—C12	113.3 (2)	C10—C9—H9	119.67
C8—C7—C12	119.9 (2)	C9—C10—H10	119.81
C7—C8—C9	119.5 (2)	C11—C10—H10	119.70
C8—C9—C10	120.6 (3)	C10—C11—H11	120.49
C9—C10—C11	120.5 (3)	C12—C11—H11	120.42
C10—C11—C12	119.1 (2)	C13—C14—H14	120.44
C6—C12—C7	113.33 (18)	C15—C14—H14	120.47
C6—C12—C11	126.3 (2)	C14—C15—H15	119.81
C7—C12—C11	120.4 (2)	C16—C15—H15	119.82
C6—C13—C14	126.3 (2)	C15—C16—H16	119.54
C6—C13—C18	113.40 (17)	C17—C16—H16	119.58
C14—C13—C18	120.26 (19)	C16—C17—H17	120.31
C13—C14—C15	119.1 (2)	C18—C17—H17	120.37
C14—C15—C16	120.4 (3)

C2—O2—C1—O1	−179.1 (3)	C7—C5—C18—C17	−124.1 (3)
C2—O2—C1—C3	0.3 (4)	C4—C6—C12—C7	−59.4 (2)
C1—O2—C2—O3	179.1 (3)	C4—C6—C12—C11	120.6 (2)
C1—O2—C2—C4	0.2 (4)	C13—C6—C12—C7	53.7 (2)
O1—C1—C3—C4	178.7 (4)	C13—C6—C12—C11	−126.3 (2)
O1—C1—C3—C5	59.9 (4)	C4—C6—C13—C14	−122.3 (3)
O2—C1—C3—C4	−0.7 (3)	C4—C6—C13—C18	59.1 (3)
O2—C1—C3—C5	−119.5 (2)	C12—C6—C13—C14	124.1 (3)
O2—C2—C4—C3	−0.6 (3)	C12—C6—C13—C18	−54.4 (2)
O2—C2—C4—C6	117.9 (3)	C5—C7—C8—C9	179.8 (2)
O3—C2—C4—C3	−179.4 (4)	C12—C7—C8—C9	−0.8 (3)
O3—C2—C4—C6	−60.8 (5)	C5—C7—C12—C6	0.8 (2)
C1—C3—C4—C2	0.8 (3)	C5—C7—C12—C11	−179.30 (18)
C1—C3—C4—C6	−119.0 (2)	C8—C7—C12—C6	−178.68 (18)
C5—C3—C4—C2	120.3 (2)	C8—C7—C12—C11	1.3 (3)
C5—C3—C4—C6	0.5 (3)	C7—C8—C9—C10	−0.1 (4)
C1—C3—C5—C7	58.3 (2)	C8—C9—C10—C11	0.6 (4)
C1—C3—C5—C18	172.10 (17)	C9—C10—C11—C12	−0.2 (4)
C4—C3—C5—C7	−57.0 (2)	C10—C11—C12—C6	179.2 (2)
C4—C3—C5—C18	56.8 (2)	C10—C11—C12—C7	−0.8 (3)
C2—C4—C6—C12	−58.7 (3)	C6—C13—C14—C15	−177.8 (3)
C2—C4—C6—C13	−172.4 (2)	C18—C13—C14—C15	0.6 (4)
C3—C4—C6—C12	56.4 (2)	C6—C13—C18—C5	0.4 (3)
C3—C4—C6—C13	−57.3 (2)	C6—C13—C18—C17	178.8 (2)
C3—C5—C7—C8	−122.5 (2)	C14—C13—C18—C5	−178.2 (2)
C3—C5—C7—C12	58.1 (2)	C14—C13—C18—C17	0.2 (4)
C18—C5—C7—C8	124.5 (2)	C13—C14—C15—C16	−0.7 (5)
C18—C5—C7—C12	−54.9 (2)	C14—C15—C16—C17	0.0 (5)
C3—C5—C18—C13	−59.3 (2)	C15—C16—C17—C18	0.8 (5)
C3—C5—C18—C17	122.5 (3)	C16—C17—C18—C5	177.3 (3)
C7—C5—C18—C13	54.2 (3)	C16—C17—C18—C13	−0.9 (4)

Symmetry codes: (i) x, −y+2, z+1/2; (ii) x+1/2, y−1/2, z+1; (iii) x+1/2, −y+3/2, z+1/2; (iv) x, y−1, z; (v) x, −y+1, z+1/2; (vi) x−1/2, −y+3/2, z−1/2; (vii) x, −y+2, z−1/2; (viii) x−1/2, y+1/2, z−1; (ix) x, y+1, z; (x) x−1/2, y+1/2, z; (xi) x+1/2, −y+5/2, z+1/2; (xii) x+1/2, y−1/2, z; (xiii) x, −y+1, z−1/2; (xiv) x−1/2, −y+5/2, z−1/2.

Experimental details

Crystal data
Chemical formula	C₁₈H₁₂O₃
M_r	276.28
Crystal system, space group	Monoclinic, Cc
Temperature (K)	293
a, b, c (Å)	15.410 (2), 9.4020 (12), 11.0939 (15)
β (°)	124.235 (10)
V (Å³)	1328.8 (3)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.09
Crystal size (mm)	0.6 × 0.4 × 0.32

Data collection
Diffractometer	Bruker SMART CCD area-detector diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	8380, 1543, 1289
R_int	0.035
(sin θ/λ)_max (Å⁻¹)	0.667

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.036, 0.084, 1.03
No. of reflections	1543
No. of parameters	190
No. of restraints	2
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.12, −0.16

Computer programs: SMART (Bruker, 1997-1998), SAINT (Bruker, 1997-1998, SAINT, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), DIAMOND (Brandenburg, 1998), SHELXL97 and PLATON (Spek, 1990).

Selected geometric parameters (Å, º) top

O1—C1	1.186 (4)	C7—C8	1.385 (4)
O2—C1	1.383 (3)	C7—C12	1.396 (3)
O2—C2	1.384 (4)	C8—C9	1.379 (4)
O3—C2	1.188 (4)	C9—C10	1.381 (4)
C1—C3	1.505 (4)	C10—C11	1.388 (5)
C2—C4	1.506 (3)	C11—C12	1.384 (3)
C3—C4	1.530 (3)	C13—C14	1.384 (3)
C3—C5	1.562 (3)	C13—C18	1.396 (3)
C4—C6	1.554 (3)	C14—C15	1.393 (4)
C5—C7	1.517 (3)	C15—C16	1.375 (4)
C5—C18	1.512 (3)	C16—C17	1.381 (4)
C6—C12	1.519 (4)	C17—C18	1.385 (3)
C6—C13	1.517 (3)

C1—O2—C2	110.6 (2)	C5—C7—C12	113.3 (2)
O1—C1—O2	119.9 (3)	C8—C7—C12	119.9 (2)
O1—C1—C3	129.8 (3)	C7—C8—C9	119.5 (2)
O2—C1—C3	110.3 (2)	C8—C9—C10	120.6 (3)
O2—C2—O3	120.2 (3)	C9—C10—C11	120.5 (3)
O2—C2—C4	110.4 (2)	C10—C11—C12	119.1 (2)
O3—C2—C4	129.4 (3)	C6—C12—C7	113.33 (18)
C1—C3—C4	104.49 (17)	C6—C12—C11	126.3 (2)
C1—C3—C5	111.2 (2)	C7—C12—C11	120.4 (2)
C4—C3—C5	110.14 (16)	C6—C13—C14	126.3 (2)
C2—C4—C3	104.17 (18)	C6—C13—C18	113.40 (17)
C2—C4—C6	111.64 (19)	C14—C13—C18	120.26 (19)
C3—C4—C6	109.93 (19)	C13—C14—C15	119.1 (2)
C3—C5—C7	106.58 (16)	C14—C15—C16	120.4 (3)
C3—C5—C18	105.9 (2)	C15—C16—C17	120.9 (3)
C7—C5—C18	107.03 (15)	C16—C17—C18	119.3 (2)
C4—C6—C12	106.69 (17)	C5—C18—C13	113.37 (16)
C4—C6—C13	106.02 (16)	C5—C18—C17	126.5 (2)
C12—C6—C13	106.98 (19)	C13—C18—C17	120.1 (2)
C5—C7—C8	126.72 (19)

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