PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of actaeInternational Union of Crystallographysearchopen accessarticle submissionjournal home pagethis article
 
Acta Crystallogr Sect E Struct Rep Online. 2009 February 1; 65(Pt 2): o312–o313.
Published online 2009 January 14. doi:  10.1107/S1600536809001020
PMCID: PMC2968396

Dimethyl 2,2′-[(4-oxo-2-phenyl-4H-chromene-5,7-diyl)dioxy]diacetate: a more densely packed polymorph

Abstract

The title mol­ecule, C21H18O8, crystallizes in two crystal polymorphs, see also Nallasivam, Nethaji, Vembu & Jaswant [Acta Cryst. (2009), E65, o314–o315]. The mol­ecules of both polymorphs differ by the conformation of the oxomethyl­acetate groups. The title mol­ecules are rather planar compared to the mol­ecules of the other polymorph. In the title mol­ecule, one of the oxomethyl­acetate groups is disordered (occupancies of 0.6058/0.3942). The structures of both polymorphs are stabilized by C—H(...)O and C—H(...)π inter­actions. Due to the planarity of the title mol­ecules and similar inter­molecular inter­actions, the title mol­ecules are more densely packed than those of the other polymorph.

Related literature

For a more detailed description of the two polymorphs, see: Nallasivam et al. (2009 [triangle]). For related structures, see: Wang, Fang et al. (2003 [triangle]); Wang, Zheng et al. (2003 [triangle]). For hydrogen bonding, see: Desiraju & Steiner (1999 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-65-0o312-scheme1.jpg

Experimental

Crystal data

  • C21H18O8
  • M r = 398.35
  • Triclinic, An external file that holds a picture, illustration, etc.
Object name is e-65-0o312-efi1.jpg
  • a = 7.4290 (15) Å
  • b = 9.2582 (19) Å
  • c = 13.480 (3) Å
  • α = 84.232 (3)°
  • β = 88.775 (4)°
  • γ = 82.982 (3)°
  • V = 915.5 (3) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 0.11 mm−1
  • T = 293 (2) K
  • 0.34 × 0.28 × 0.22 mm

Data collection

  • Bruker SMART APEX CCD diffractometer
  • Absorption correction: multi-scan (SADABS; Sheldrick, 1998 [triangle]) T min = 0.963, T max = 0.975
  • 9755 measured reflections
  • 3781 independent reflections
  • 2887 reflections with I > 3σ(I)
  • R int = 0.016

Refinement

  • R[F 2 > 2σ(F 2)] = 0.059
  • wR(F 2) = 0.118
  • S = 2.47
  • 3781 reflections
  • 268 parameters
  • H-atom parameters constrained
  • Δρmax = 0.40 e Å−3
  • Δρmin = −0.26 e Å−3

Data collection: SMART (Bruker, 1999 [triangle]); cell refinement: SAINT (Bruker, 1999 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: JANA2000 (Petříček et al., 2000 [triangle]); molecular graphics: PLATON (Spek, 2003 [triangle]); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008 [triangle]) and JANA2000.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809001020/fb2129sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809001020/fb2129Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

AN thanks Dr Naresh Kumar and Dr G. Vengatachalam, School of Chemistry, Bharathidasan University, Tiruchirappalli, and Organica Aromatics Pvt Ltd, Bangalore, India, for providing laboratory facilities.

supplementary crystallographic information

Comment

The importance of the benzopyrans and their derivatives is described in Nallasivam et al. (2009).

The chromene ring is almost planar and similar to that found in the related chromene derivatives (Wang, Zheng et al., 2003; Wang, Fang et al., 2003). The total puckering amplitude of the chromene ring is 0.040 (2)Å. The interplanar angle between the chromene ring and the 2-phenyl ring is 2.90 (6)° thereby indicating the almost coplanar arrangement (Fig. 1). The oxomethylacetate substituent at C7 is slightly distorted from coplanarity as discerned from the interplanar angle of 12.7 (1)°. Such a calculation for the oxomethylacetate group at C5 is not done due to disorder.

The crystal structure is stabilized by the interplay of C–H···O, C–H···π interactions (Tab. 1) as well as π···π-electron interactions. The H-bond distances agree with those reported in literature (Desiraju & Steiner, 1999). There is a π···π-electron interaction between the rings C5\C6···\C10 Cg2 and C11\C12···\C16 [1-x, 2-y, 2-z] whose centroids are at the distance 3.714 (1) Å.

Experimental

Into the round bottom flask a suspension of chrysin (3.93 mmol, 1 g) and potassium carbonate (11.81 mmol, 1.64 g) were deposited and to this mixture dimethylformamide (10 ml) was added. The reaction mixture was heated to 383 K and maintained at this temperature for 2–3 hrs. The reaction mixture was cooled to 353 K. Methyl chloroacetate (15.74 mmol, 1.70 g) was slowly added to the reaction mixture with the help of a dropping funnel. The reaction mixture was kept for 8–9 hrs at 353 K while the reaction was monitored by high pressure liquid chromatography. Once the reaction was completed, the reaction mixture was quenched with water and stirred for 30–45 min at 303 K. The obtained solid was filtered and washed with plenty of water followed by methanol. The wet cake was dried under vacuum at 343 K. The crude product of the title compound, i. e. the more densely packed polymorph, was dissolved in dichloromethane (10 ml) and mixed with equal amount of n-hexane. The clear solution was kept aside for a week without stirring. Diffraction quality prism shaped crystals with average size about 0.30 mm along the longest edge were obtained. The crystals were filtered and washed with n-hexane and dried under vacuum at 70°C. Yield: 85%

Refinement

Though the hydrogen atoms were observable in the difference electron density maps they were situated into the idealized positions and refined in the riding mode approximation. The following constraints have been applied: C–H = 0.93, 0.97 and 0.96Å for aryl, methylene and methyl H, respectively. Uiso(H)=1.2Ueq(C) for the aryl and methylene H and Uiso(H)=1.5Ueq(C) for the methyl H. A considerably elongated displacement parameter of the atom O21 and electron density maxima in the vicinity of the disordered chain atoms indicated disorder. This disorder has been modelled by two fragments whose geometry was assumed to be equal with relatively same displacement parameters that differed only by their orientation that was refined. At the beginning, the atoms of the disordered fragment were refined isotropically while their occupational parameters were refined. The occupational parameters converged to the values 0.394 (4) and 0.606 (4), respectively. In the next stage, the occupational parameters were fixed while the non-hydrogen atoms of the disordered atoms were refined anisotropically. The plausibility of the result follows from the planarity of the disordered fragments C19A\C20A\O21A\O22A and C19B\C20B\O21B\O22B with maximal deviations from planarity that equal to 0.006 (7) Å for C20A and 0.007 (65)Å for C20B.

Figures

Fig. 1.
The asymmetric unit of the title compound with the atoms labelled and displacement ellipsoids depicted at the 50% probability level for all non-H atoms. H-atoms are drawn as spheres of arbitrary radius.

Crystal data

C21H18O8Z = 2
Mr = 398.35F(000) = 416
Triclinic, P1Dx = 1.445 Mg m3
Hall symbol: -P 1Melting point = 411–414 K
a = 7.4290 (15) ÅMo Kα radiation, λ = 0.71073 Å
b = 9.2582 (19) ÅCell parameters from 574 reflections
c = 13.480 (3) Åθ = 1.5–26.5°
α = 84.232 (3)°µ = 0.11 mm1
β = 88.775 (4)°T = 293 K
γ = 82.982 (3)°Rectangular, colourless
V = 915.5 (3) Å30.34 × 0.28 × 0.22 mm

Data collection

Bruker SMART APEX CCD diffractometer3781 independent reflections
Radiation source: fine-focus sealed tube2887 reflections with I > 3σ(I)
graphiteRint = 0.016
Detector resolution: 0.3 pixels mm-1θmax = 27.4°, θmin = 1.5°
ω scansh = −9→9
Absorption correction: multi-scan (SADABS; Sheldrick, 1998)k = −11→11
Tmin = 0.963, Tmax = 0.975l = −17→17
9755 measured reflections

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.059Hydrogen site location: difference Fourier map
wR(F2) = 0.118H-atom parameters constrained
S = 2.47Weighting scheme based on measured s.u.'s w = 1/[σ2(I) + 0.0004I2]
3781 reflections(Δ/σ)max = 0.018
268 parametersΔρmax = 0.40 e Å3
0 restraintsΔρmin = −0.26 e Å3
73 constraints

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

xyzUiso*/UeqOcc. (<1)
O10.30663 (16)0.96130 (13)1.06056 (8)0.0466 (4)
C20.3857 (2)0.82585 (19)1.09503 (13)0.0431 (6)
C30.4037 (2)0.7161 (2)1.03579 (13)0.0481 (7)
H30.4623820.6280891.0649550.0577*
C40.3379 (2)0.73194 (19)0.93493 (13)0.0447 (6)
C50.1751 (2)0.92338 (19)0.80498 (13)0.0440 (6)
C60.0924 (2)1.06310 (19)0.78160 (13)0.0485 (7)
H60.0402961.0875980.719110.0582*
C70.0866 (2)1.16664 (19)0.85047 (13)0.0431 (6)
C80.1604 (2)1.13114 (18)0.94310 (12)0.0425 (6)
H80.1569761.2005970.9885990.051*
C90.2523 (2)0.87883 (19)0.90045 (12)0.0412 (6)
C100.2396 (2)0.98822 (19)0.96535 (12)0.0404 (6)
C110.4412 (2)0.82212 (19)1.19964 (13)0.0442 (6)
C120.4040 (3)0.9455 (2)1.25078 (13)0.0566 (7)
H120.3437111.0310751.21910.0679*
C130.4559 (3)0.9425 (2)1.34867 (14)0.0662 (9)
H130.4304551.0250511.3828860.0795*
C140.5450 (3)0.8187 (2)1.39655 (15)0.0682 (9)
H140.5797560.8188941.4623940.0818*
C150.5827 (3)0.6948 (2)1.34736 (14)0.0639 (8)
H150.642950.6100211.3802210.0767*
C160.5311 (3)0.6965 (2)1.24944 (14)0.0540 (7)
H160.5571340.6123941.2168130.0648*
O170.3521 (2)0.62674 (13)0.88447 (9)0.0631 (5)
O240.00341 (17)1.30050 (13)0.81551 (9)0.0543 (5)
C250.0005 (3)1.41742 (19)0.87637 (13)0.0510 (7)
H25a−0.0426761.3867770.9426670.0612*
H25b0.1224181.442960.8818420.0612*
C26−0.1214 (3)1.5488 (2)0.83259 (14)0.0515 (7)
O27−0.1465 (2)1.65854 (16)0.87223 (11)0.0857 (7)
O28−0.19680 (19)1.52877 (14)0.74809 (10)0.0629 (5)
C29−0.3222 (3)1.6483 (2)0.70402 (17)0.0749 (9)
H29a−0.2585651.7311940.6851060.1124*
H29b−0.4157531.6739720.7515520.1124*
H29c−0.3755751.6191650.6460840.1124*
O18a0.1645 (15)0.8187 (11)0.7443 (6)0.0454 (13)0.3942
C19a0.1208 (13)0.8711 (7)0.6431 (7)0.0539 (9)0.3942
H19aa0.2081070.935250.6167620.0647*0.3942
H19ba−0.0023030.9201370.6401240.0647*0.3942
C20a0.1342 (9)0.7395 (6)0.5854 (5)0.0499 (10)0.3942
O21a0.2023 (7)0.6206 (5)0.6126 (4)0.0810 (12)0.3942
O22a0.0619 (16)0.7758 (10)0.4972 (6)0.0728 (8)0.3942
C23a0.0795 (19)0.6627 (13)0.4291 (6)0.0683 (15)0.3942
H23aa−0.0191730.6801750.382960.1025*0.3942
H23ba0.1923140.6642250.3931530.1025*0.3942
H23ca0.0771360.5688380.4662910.1025*0.3942
O18b0.209 (9)0.823 (7)0.734 (4)0.0454 (12)0.6058
C19b0.108 (9)0.860 (7)0.643 (4)0.0539 (9)0.6058
H19ab0.1360.9550.6130.0647*0.6058
H19bb−0.0200.8610.6580.0647*0.6058
C20b0.169 (9)0.745 (7)0.575 (4)0.0499 (10)0.6058
O21b0.298 (9)0.657 (7)0.585 (4)0.0810 (13)0.6058
O22b0.058 (9)0.756 (7)0.500 (4)0.0728 (9)0.6058
C23b0.109 (9)0.660 (7)0.422 (4)0.0683 (14)0.6058
H23ab0.0020.6410.3900.1025*0.6058
H23bb0.1880.7050.3750.1025*0.6058
H23cb0.1710.5690.4520.1025*0.6058

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O10.0634 (8)0.0405 (7)0.0362 (7)−0.0007 (6)−0.0085 (6)−0.0092 (5)
C20.0488 (11)0.0395 (10)0.0406 (10)−0.0030 (8)−0.0026 (8)−0.0041 (8)
C30.0613 (12)0.0393 (11)0.0422 (11)0.0007 (9)−0.0052 (9)−0.0034 (9)
C40.0550 (12)0.0397 (10)0.0407 (10)−0.0067 (9)−0.0008 (9)−0.0092 (8)
C50.0542 (11)0.0415 (11)0.0382 (10)−0.0048 (9)−0.0028 (9)−0.0141 (8)
C60.0610 (12)0.0460 (11)0.0389 (10)0.0007 (9)−0.0115 (9)−0.0126 (9)
C70.0493 (11)0.0387 (10)0.0415 (11)0.0004 (8)−0.0071 (8)−0.0101 (8)
C80.0508 (11)0.0382 (10)0.0405 (10)−0.0035 (8)−0.0024 (9)−0.0150 (8)
C90.0488 (11)0.0389 (10)0.0369 (10)−0.0053 (8)−0.0006 (8)−0.0084 (8)
C100.0463 (11)0.0428 (10)0.0330 (10)−0.0058 (8)−0.0043 (8)−0.0070 (8)
C110.0501 (11)0.0446 (11)0.0387 (10)−0.0061 (9)−0.0041 (8)−0.0063 (8)
C120.0733 (14)0.0501 (12)0.0450 (12)0.0026 (10)−0.0118 (10)−0.0074 (9)
C130.0943 (17)0.0586 (14)0.0456 (12)0.0007 (12)−0.0151 (12)−0.0133 (10)
C140.0906 (16)0.0720 (15)0.0415 (12)−0.0047 (13)−0.0191 (11)−0.0061 (11)
C150.0808 (15)0.0557 (13)0.0513 (13)0.0012 (11)−0.0194 (11)0.0061 (11)
C160.0660 (13)0.0469 (12)0.0483 (12)−0.0028 (10)−0.0051 (10)−0.0050 (9)
O170.0964 (11)0.0410 (8)0.0521 (8)0.0037 (7)−0.0148 (8)−0.0163 (7)
O240.0758 (9)0.0410 (7)0.0454 (8)0.0097 (7)−0.0183 (7)−0.0176 (6)
C250.0640 (13)0.0451 (11)0.0462 (11)−0.0016 (9)−0.0113 (9)−0.0188 (9)
C260.0646 (13)0.0428 (11)0.0482 (11)−0.0004 (9)−0.0069 (10)−0.0169 (9)
O270.1173 (13)0.0557 (9)0.0844 (11)0.0210 (9)−0.0296 (10)−0.0403 (9)
O280.0860 (10)0.0460 (8)0.0543 (8)0.0130 (7)−0.0227 (7)−0.0150 (7)
C290.0941 (18)0.0538 (13)0.0706 (15)0.0179 (12)−0.0208 (13)−0.0041 (11)
O18a0.064 (4)0.0384 (9)0.0340 (10)−0.0010 (16)−0.0036 (17)−0.0123 (6)
C19a0.0779 (19)0.0424 (12)0.0428 (11)−0.0047 (12)−0.0164 (12)−0.0109 (10)
C20a0.067 (2)0.0432 (13)0.0399 (13)−0.0034 (13)−0.0088 (14)−0.0072 (10)
O21a0.126 (3)0.0534 (12)0.0584 (17)0.025 (2)−0.026 (2)−0.0159 (11)
O22a0.1281 (17)0.0475 (14)0.0427 (8)0.0023 (14)−0.0274 (10)−0.0139 (8)
C23a0.104 (4)0.0602 (17)0.0447 (13)−0.0086 (18)−0.0085 (16)−0.0243 (12)
O18b0.054 (3)0.0478 (18)0.0344 (12)0.0054 (17)−0.0039 (15)−0.0159 (11)
C19b0.0620 (16)0.0513 (16)0.0491 (12)0.0063 (11)−0.0157 (11)−0.0211 (11)
C20b0.0555 (19)0.0502 (17)0.0436 (14)0.0037 (13)−0.0099 (13)−0.0131 (12)
O21b0.074 (3)0.097 (2)0.0673 (19)0.0350 (17)−0.0209 (19)−0.0378 (15)
O22b0.0888 (16)0.0733 (18)0.0544 (9)0.0260 (12)−0.0302 (9)−0.0340 (9)
C23b0.091 (3)0.070 (2)0.0462 (15)0.0046 (19)−0.0098 (15)−0.0298 (14)

Geometric parameters (Å, °)

O1—C21.359 (2)C25—H25a0.9700
O1—C101.375 (2)C25—H25b0.970
C2—C31.347 (3)C25—C261.502 (2)
C2—C111.474 (2)C26—O271.188 (3)
C3—H30.9300C26—O281.319 (2)
C3—C41.442 (2)O28—C291.444 (2)
C4—C91.464 (2)C29—H29a0.960
C4—O171.236 (2)C29—H29b0.960
C5—C61.372 (2)C29—H29c0.960
C5—C91.422 (2)O18a—C19a1.431 (13)
C5—O18a1.340 (10)C19a—H19aa0.970
C5—O18b1.40 (6)C19a—H19ba0.970
C6—H60.9300C19a—C20a1.503 (10)
C6—C71.396 (3)C19a—H19ab0.86
C7—C81.368 (2)H19ba—C19b0.93
C7—O241.3593 (19)C20a—O21a1.181 (7)
C8—H80.9300C20a—O22a1.310 (11)
C8—C101.387 (2)O22a—C23a1.453 (15)
C9—C101.397 (3)C23a—H23aa0.960
C11—C121.389 (3)C23a—H23ba0.960
C11—C161.387 (2)C23a—H23ca0.960
C12—H120.9300O18b—C19b1.43 (8)
C12—C131.379 (3)C19b—H19ab0.97
C13—H130.930C19b—H19bb0.97
C13—C141.360 (3)C19b—C20b1.50 (9)
C14—H140.930C20b—O21b1.18 (9)
C14—C151.379 (3)C20b—O22b1.31 (8)
C15—H150.930O22b—C23b1.45 (9)
C15—C161.380 (3)C23b—H23ab0.96
C16—H160.930C23b—H23bb0.96
O24—C251.420 (2)C23b—H23cb0.96
C2—O1—C10120.73 (14)H25a—C25—H25b108.35
O1—C2—C3120.63 (15)H25a—C25—C26109.47
O1—C2—C11110.99 (15)H25b—C25—C26109.47
C3—C2—C11128.38 (15)C25—C26—O27122.01 (18)
C2—C3—H3114.72C25—C26—O28113.56 (16)
C2—C3—C4123.30 (15)O27—C26—O28124.42 (17)
H3—C3—C4121.98C26—O28—C29116.61 (15)
C3—C4—C9114.63 (16)O28—C29—H29a109.5
C3—C4—O17120.99 (15)O28—C29—H29b109.47
C9—C4—O17124.36 (16)O28—C29—H29c109.47
C6—C5—C9121.19 (17)H29a—C29—H29b109.5
C6—C5—O18a121.2 (4)H29a—C29—H29c109.5
C6—C5—O18b122 (2)H29b—C29—H29c109.5
C9—C5—O18a117.0 (4)C5—O18a—C19a114.8 (7)
C9—C5—O18b116 (2)C5—O18a—C19b119 (3)
C5—C6—H6118.85O18a—C19a—H19aa109.5
C5—C6—C7120.54 (16)O18a—C19a—H19ba109.5
H6—C6—C7120.61O18a—C19a—C20a106.9 (6)
C6—C7—C8121.07 (15)O18a—C19a—C20b109 (2)
C6—C7—O24113.49 (14)H19aa—C19a—H19ba112.0 (6)
C8—C7—O24125.43 (16)H19aa—C19a—C20a109.5 (8)
C7—C8—H8120.81H19ba—C19a—C20a109.5 (8)
C7—C8—C10117.06 (16)C19a—C20a—O21a126.3 (7)
H8—C8—C10122.13C19a—C20a—O22a110.0 (6)
C4—C9—C5126.02 (16)O21a—C20a—O22a123.7 (7)
C4—C9—C10119.19 (15)C20a—O22a—C23a116.3 (8)
C5—C9—C10114.79 (15)O22a—C23a—H23aa109.5
O1—C10—C8113.17 (15)O22a—C23a—H23ba109.5
O1—C10—C9121.50 (14)O22a—C23a—H23ca109.5
C8—C10—C9125.33 (15)H23aa—C23a—H23ba109.5
C2—C11—C12120.37 (15)H23aa—C23a—H23ca109.5
C2—C11—C16121.24 (16)H23ba—C23a—H23ca109.5
C12—C11—C16118.39 (16)C5—O18b—C19a113 (4)
C11—C12—H12120.07C5—O18b—C19b115 (5)
C11—C12—C13120.55 (17)C5—O18b—C19b115 (5)
H12—C12—C13119.4O18b—C19b—H19ab109
C12—C13—H13120.44O18b—C19b—H19bb109
C12—C13—C14120.5 (2)O18b—C19b—C20b107
H13—C13—C14119.07H19ab—C19b—H19bb112
C13—C14—H14119.3H19ab—C19b—C20b109
C13—C14—C15119.95 (19)H19bb—C19b—C20b109
H14—C14—C15120.7C19b—C20b—O21b126 (6)
C14—C15—H15119.9C19b—C20b—O22b110 (6)
C14—C15—C16120.03 (18)O21b—C20b—O22b124 (6)
H15—C15—C16120.0C20b—O22b—C23b116 (6)
C11—C16—C15120.57 (18)O22b—C23b—H23ab109
C11—C16—H16119.94O22b—C23b—H23bb109
C15—C16—H16119.49O22b—C23b—H23cb109
C7—O24—C25118.58 (13)H23ab—C23b—H23bb109
O24—C25—H25a109.47H23ab—C23b—H23cb109
O24—C25—H25b109.47H23bb—C23b—H23cb109
O24—C25—C26110.57 (15)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
C8—H8···O27i0.932.383.304 (2)169
C12—H12···O10.932.332.664 (2)101
C15—H15···O21Bii0.932.463.31 (6)153
C25—H25B···O17iii0.972.563.447 (3)153
C29—H29B···O17iv0.962.503.403 (3)156
C29—H29C···O21Biv0.962.553.26 (6)131
C23B—H23BB···Cg1v0.962.763.67 (6)159 (6)

Symmetry codes: (i) −x, −y+3, −z+2; (ii) −x+1, −y+1, −z+2; (iii) x, y+1, z; (iv) x−1, y+1, z; (v) x, y, z−1.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: FB2129).

References

  • Bruker (1999). SMART and SAINT Bruker AXS Inc, Madison, Wisconsin, USA.
  • Desiraju, G. R. & Steiner, T. (1999). The Weak Hydrogen Bond in Structural Chemistry and Biology. New York: Oxford University Press.
  • Nallasivam, A., Nethaji, M., Vembu, N., Jaswant, B. & Sulochana, N. (2009). Acta Cryst. E65, o314–o315. [PMC free article] [PubMed]
  • Petříček, V., Dušek, M. & Palatinus, L. (2000). JANA2000 Institute of Physics, Czech Academy of Science, Czech Republic.
  • Sheldrick, G. M. (1998). SADABS University of Göttingen, Germany.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Spek, A. L. (2003). J. Appl. Cryst.36, 7–13.
  • Wang, J.-F., Fang, M.-J., Huang, H.-Q., Li, G.-L., Su, W.-J. & Zhao, Y.-F. (2003). Acta Cryst. E59, o1517–o1518.
  • Wang, J.-F., Zhang, Y.-J., Fang, M.-J., Huang, Y.-J., Wei, Z.-B., Zheng, Z.-H., Su, W.-J. & Zhao, Y.-F. (2003). Acta Cryst. E59, o1244–o1245.

Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of International Union of Crystallography