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Acta Crystallogr Sect E Struct Rep Online. 2009 January 1; 65(Pt 1): o191.
Published online 2008 December 20. doi:  10.1107/S1600536808043055
PMCID: PMC2968099

Ethyl 6-r-(2-chlorophenyl)-2-oxo-4-phenyl­cyclohex-3-ene-1-t-carboxylate

Abstract

In the title mol­ecule, C21H19ClO3, the cyclo­hexene ring adopts an envelope conformation, with all substituents equatorial. The plane through its five coplanar atoms makes dihedral angles of 12.75 (14) and 74.16 (8)° with the phenyl and benzene rings, respectively. The dihedral angle between the latter two rings is 81.73 (12)°. Inter­molecular C—H(...)O hydrogen bonds and intra­molecular C—H(...)Cl contacts are found in the crystal structure; a weak C—H(...)π inter­action is also present.

Related literature

For synthetic applications and biological activities, see: Cokcer et al. (1995 [triangle]); Friedrich et al. (2006 [triangle]); Pandey et al.(2004 [triangle]); Rebacz et al. (2007 [triangle]). For related crystal structures, see: Guzei (2004 [triangle]); Shishkina et al. (2002 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-65-0o191-scheme1.jpg

Experimental

Crystal data

  • C21H19ClO3
  • M r = 354.81
  • Triclinic, An external file that holds a picture, illustration, etc.
Object name is e-65-0o191-efi1.jpg
  • a = 8.0115 (3) Å
  • b = 11.3525 (4) Å
  • c = 11.6386 (4) Å
  • α = 62.261 (2)°
  • β = 77.975 (2)°
  • γ = 75.297 (2)°
  • V = 901.16 (6) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 0.23 mm−1
  • T = 293 (2) K
  • 0.25 × 0.20 × 0.20 mm

Data collection

  • Bruker Kappa APEXII CCD diffractometer
  • Absorption correction: multi-scan (SADABS; Bruker, 2004 [triangle]) T min = 0.945, T max = 0.956
  • 17066 measured reflections
  • 3885 independent reflections
  • 2825 reflections with I > 2σ(I)
  • R int = 0.028

Refinement

  • R[F 2 > 2σ(F 2)] = 0.045
  • wR(F 2) = 0.137
  • S = 1.05
  • 3885 reflections
  • 227 parameters
  • H-atom parameters constrained
  • Δρmax = 0.53 e Å−3
  • Δρmin = −0.39 e Å−3

Data collection: APEX2 (Bruker, 2004 [triangle]); cell refinement: SAINT-NT (Bruker, 2004 [triangle]); data reduction: SAINT-NT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: ORTEP-3 (Farrugia, 1997 [triangle]); software used to prepare material for publication: PLATON (Spek, 2003 [triangle]).

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808043055/wn2298sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808043055/wn2298Isup2.hkl

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

Acknowledgments

AT thanks the UGC, India, for the award of a Minor Research Project [File No. MRP-2355/06(UGC-SERO), Link No. 2355, 10/01/2007].

supplementary crystallographic information

Comment

Cyclohex-2-enone derivatives exhibit antifungal (Friedrich et al., 2006) and anticancer (Rebacz et al., 2007) activities. Cyclohex-2-enones have also been used in organic synthesis (Cokcer et al., 1995; Pandey et al., 2004).

Guzei (2004) has reported a crystal structure determination of 4,4,6,6-tetraphenylcyclohex-2-en-1-one, wherein the cyclohexenone ring is in a half-chair conformation. Shishkina et al. (2002) have reported the molecular structures of chloro-, methoxy- and methoxyphenyl-substituted (1R)-arylidene-p-(4-menthen)-3-ones. The cyclohexenone ring in these compounds has a sofa conformation.

The present X-ray diffraction study was undertaken to determine how the conformation of the system is affected by the substitution of a phenyl group at position 4, chlorophenyl group at position 6 and ethoxycarbonyl group at position 1 of the cyclohexenone ring.

In the title molecule, C21H19ClO3, (Fig. 1), the cyclohexene ring adopts an envelope conformation, with all substituents equatorial. The plane through the five coplanar atoms C1/C2/C3/C4/C6 makes dihedral angles of 12.75 (14)° and 74.16 (8)° with the phenyl and benzene rings, respectively. The dihedral angle between the phenyl and benzene rings is 81.73 (12)°. C33—H33···O16(1 + x, -1 + y, z) and C56—H56···O16(-x, 1 - y, -z) intermolecular hydrogen bonds and a C5—H5···Cl2 intramolecular contact are found in the crystal structure. Furthermore, a C17—H17A···π(-1 + x, y, z) interaction involving the benzene (C51—C56) ring is also found (Fig. 2, Table 1).

Experimental

A mixture of o-chlorobenzylideneacetophenone (3.65 g, 0.015 mol), ethyl acetoacetate (2 ml, 0.015 mol) and sodium ethoxide (1 g, 0.015 mol) in absolute alcohol (50 ml) was refluxed for 14 h. After cooling, the reaction mixture was neutralized with 0.1 N HCl. It was than extracted with diethyl ether (3x20 ml). The organic layer was dried over anhydrous sodium sulfate, filtered and the solvents removed by rotary vacuum evaporation. A solid mass was obtained which was recrystallized from ethanol. Yield 2.22 g (61%).

Refinement

H atoms were positioned geometrically and allowed to ride on their parent atoms, with Csp2—H = 0.93, C(methyl)—H = 0.96, C(methylene)—H = 0.97 and C(methine)—H = 0.98 Å; Uiso(H) = kUeq(C), where k = 1.5 for methyl and 1.2 for all other H atoms.

Figures

Fig. 1.
The molecular structure of the title compound, showing the atom-numbering scheme and displacement ellipsoids drawn at the 30% probability level. H atoms have been omitted for clarity.
Fig. 2.
The packing of the title compound, viewed down the a axis. Dashed lines indicate hydrogen bonds. H atoms not involved in hydrogen bonding have been omitted.

Crystal data

C21H19ClO3Z = 2
Mr = 354.81F(000) = 372
Triclinic, P1Dx = 1.308 Mg m3
Hall symbol: -P 1Melting point: 389 K
a = 8.0115 (3) ÅMo Kα radiation, λ = 0.71073 Å
b = 11.3525 (4) ÅCell parameters from 6137 reflections
c = 11.6386 (4) Åθ = 2.2–26.9°
α = 62.261 (2)°µ = 0.23 mm1
β = 77.975 (2)°T = 293 K
γ = 75.297 (2)°Prism, yellow
V = 901.16 (6) Å30.25 × 0.20 × 0.20 mm

Data collection

Bruker Kappa APEXII CCD diffractometer3885 independent reflections
Radiation source: fine-focus sealed tube2825 reflections with I > 2σ(I)
graphiteRint = 0.028
ω and [var phi] scanθmax = 27.0°, θmin = 2.2°
Absorption correction: multi-scan (SADABS; Bruker, 2004)h = −9→10
Tmin = 0.945, Tmax = 0.956k = −14→14
17066 measured reflectionsl = −14→14

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)] = 0.045Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.137H-atom parameters constrained
S = 1.05w = 1/[σ2(Fo2) + (0.0591P)2 + 0.4414P] where P = (Fo2 + 2Fc2)/3
3885 reflections(Δ/σ)max = 0.001
227 parametersΔρmax = 0.53 e Å3
0 restraintsΔρmin = −0.39 e Å3

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su'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 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 > 2σ(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 (Å2)

xyzUiso*/Ueq
Cl20.13654 (11)0.11707 (7)0.54241 (6)0.0761 (3)
O1−0.1208 (2)0.14508 (16)0.06258 (18)0.0571 (6)
O16−0.2286 (2)0.41679 (16)0.13239 (17)0.0681 (6)
O17−0.2157 (2)0.21683 (16)0.30479 (16)0.0604 (5)
C10.0078 (3)0.13601 (19)0.10828 (19)0.0377 (6)
C20.1564 (3)0.02735 (19)0.12187 (19)0.0384 (6)
C30.3039 (2)0.01717 (17)0.16536 (17)0.0335 (5)
C40.3214 (2)0.11953 (19)0.20808 (19)0.0371 (6)
C50.1463 (2)0.18685 (17)0.25162 (17)0.0323 (5)
C60.0221 (2)0.24349 (17)0.14675 (18)0.0342 (5)
C16−0.1553 (3)0.30400 (19)0.1907 (2)0.0410 (6)
C17−0.3782 (3)0.2616 (3)0.3678 (3)0.0766 (10)
C18−0.3479 (5)0.3014 (5)0.4614 (4)0.127 (2)
C310.4544 (2)−0.09227 (18)0.17178 (18)0.0349 (5)
C320.4368 (3)−0.2036 (2)0.1583 (3)0.0515 (8)
C330.5756 (3)−0.3071 (2)0.1670 (3)0.0587 (8)
C340.7342 (3)−0.3016 (2)0.1883 (2)0.0517 (7)
C350.7554 (3)−0.1921 (2)0.1997 (2)0.0491 (7)
C360.6165 (3)−0.0874 (2)0.1915 (2)0.0439 (7)
C510.1649 (2)0.29528 (18)0.28709 (18)0.0341 (5)
C520.1578 (3)0.2746 (2)0.4147 (2)0.0420 (6)
C530.1702 (3)0.3765 (3)0.4449 (2)0.0546 (8)
C540.1925 (3)0.5008 (2)0.3465 (3)0.0570 (9)
C550.2043 (3)0.5233 (2)0.2197 (3)0.0527 (8)
C560.1904 (3)0.42222 (19)0.1901 (2)0.0435 (6)
H20.14847−0.039160.098930.0461*
H4A0.379370.188520.136320.0445*
H4B0.393180.075100.279670.0445*
H50.096110.116930.330160.0388*
H60.069630.315860.069160.0410*
H17A−0.445930.337520.302410.0921*
H17B−0.444410.188810.411650.0921*
H18A−0.277890.227130.524620.1908*
H18B−0.456890.326570.504650.1908*
H18C−0.288700.377100.417230.1908*
H320.32983−0.208370.143060.0618*
H330.56122−0.381220.158320.0704*
H340.82717−0.372050.195040.0620*
H350.86358−0.187570.213140.0589*
H360.63254−0.013260.199240.0527*
H530.163260.360440.531530.0656*
H540.199700.569730.366230.0684*
H550.221780.607250.152880.0632*
H560.198360.439320.103000.0523*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Cl20.1257 (7)0.0703 (4)0.0378 (3)−0.0459 (4)−0.0124 (3)−0.0126 (3)
O10.0451 (9)0.0615 (10)0.0857 (12)0.0041 (7)−0.0264 (8)−0.0483 (9)
O160.0714 (12)0.0474 (9)0.0641 (11)0.0224 (8)−0.0139 (9)−0.0204 (8)
O170.0408 (9)0.0560 (9)0.0612 (10)0.0038 (7)0.0040 (7)−0.0166 (8)
C10.0378 (10)0.0388 (10)0.0428 (10)−0.0026 (8)−0.0093 (8)−0.0231 (8)
C20.0408 (11)0.0365 (9)0.0479 (11)−0.0026 (8)−0.0088 (8)−0.0271 (8)
C30.0362 (10)0.0312 (8)0.0358 (9)−0.0033 (7)−0.0041 (7)−0.0180 (7)
C40.0353 (10)0.0368 (9)0.0462 (10)−0.0036 (8)−0.0086 (8)−0.0237 (8)
C50.0359 (9)0.0286 (8)0.0349 (9)−0.0042 (7)−0.0051 (7)−0.0162 (7)
C60.0368 (10)0.0312 (8)0.0367 (9)−0.0030 (7)−0.0073 (7)−0.0168 (7)
C160.0422 (11)0.0374 (10)0.0465 (11)0.0027 (8)−0.0119 (9)−0.0229 (9)
C170.0411 (14)0.097 (2)0.0765 (19)0.0071 (13)0.0046 (12)−0.0396 (17)
C180.080 (2)0.208 (5)0.092 (3)0.017 (3)−0.005 (2)−0.088 (3)
C310.0368 (10)0.0316 (9)0.0360 (9)−0.0018 (7)−0.0048 (7)−0.0163 (7)
C320.0427 (12)0.0403 (11)0.0781 (16)−0.0003 (9)−0.0125 (10)−0.0323 (11)
C330.0542 (14)0.0395 (11)0.0866 (18)0.0027 (10)−0.0109 (12)−0.0352 (12)
C340.0449 (12)0.0451 (11)0.0546 (13)0.0100 (9)−0.0069 (10)−0.0215 (10)
C350.0363 (11)0.0574 (13)0.0534 (12)0.0014 (9)−0.0091 (9)−0.0272 (10)
C360.0409 (11)0.0464 (11)0.0502 (12)−0.0031 (9)−0.0081 (9)−0.0270 (10)
C510.0318 (9)0.0336 (9)0.0412 (10)−0.0022 (7)−0.0060 (7)−0.0209 (8)
C520.0449 (11)0.0455 (11)0.0420 (10)−0.0098 (9)−0.0032 (8)−0.0240 (9)
C530.0567 (14)0.0699 (15)0.0593 (14)−0.0141 (11)−0.0016 (11)−0.0468 (13)
C540.0540 (14)0.0514 (13)0.0883 (18)−0.0058 (10)−0.0114 (12)−0.0494 (13)
C550.0541 (13)0.0330 (10)0.0732 (16)−0.0078 (9)−0.0194 (11)−0.0200 (10)
C560.0511 (12)0.0365 (10)0.0449 (11)−0.0096 (9)−0.0104 (9)−0.0163 (9)

Geometric parameters (Å, °)

Cl2—C521.735 (2)C52—C531.387 (4)
O1—C11.216 (3)C53—C541.369 (4)
O16—C161.192 (3)C54—C551.362 (4)
O17—C161.315 (3)C55—C561.377 (4)
O17—C171.451 (4)C2—H20.9300
C1—C21.454 (3)C4—H4A0.9700
C1—C61.518 (3)C4—H4B0.9700
C2—C31.338 (3)C5—H50.9800
C3—C41.506 (3)C6—H60.9800
C3—C311.481 (3)C17—H17A0.9700
C4—C51.526 (3)C17—H17B0.9700
C5—C61.531 (2)C18—H18A0.9600
C5—C511.517 (3)C18—H18B0.9600
C6—C161.511 (3)C18—H18C0.9600
C17—C181.440 (6)C32—H320.9300
C31—C321.388 (3)C33—H330.9300
C31—C361.384 (3)C34—H340.9300
C32—C331.379 (4)C35—H350.9300
C33—C341.366 (4)C36—H360.9300
C34—C351.365 (3)C53—H530.9300
C35—C361.388 (3)C54—H540.9300
C51—C521.383 (3)C55—H550.9300
C51—C561.390 (3)C56—H560.9300
Cl2···O17i3.303 (2)C36···H4A3.0700
Cl2···H52.5600C52···H17Bviii3.0800
O1···O173.181 (3)C53···H18Bviii3.0600
O1···C36ii3.386 (3)C55···H17Aviii3.0800
O16···C56iii3.308 (3)C55···H34iv2.9700
O16···C33iv3.296 (3)C56···H4A2.9700
O17···O13.181 (3)C56···H62.6700
O17···C513.329 (2)H2···C322.5600
O17···Cl2i3.303 (2)H2···H322.0100
O1···H2v2.7300H2···O1v2.7300
O1···H32v2.9200H4A···C363.0700
O1···H36ii2.7400H4A···C562.9700
O1···H55iii2.8200H4A···H362.5700
O16···H56iii2.4500H4B···C362.6400
O16···H33iv2.5800H4B···H362.1700
O16···H17A2.3400H5···Cl22.5600
O17···H52.4800H5···O172.4800
C1···C34vi3.561 (3)H5···C22.9500
C1···C35vi3.537 (3)H6···C562.6700
C2···C36vi3.554 (3)H6···H562.1400
C2···C35vi3.325 (3)H17A···O162.3400
C16···C563.368 (4)H17A···C55ii3.0800
C17···C53ii3.597 (4)H17B···C52ii3.0800
C31···C31vi3.560 (3)H18B···C53ii3.0600
C33···O16vii3.296 (3)H18C···C163.0300
C34···C1vi3.561 (3)H32···C22.6100
C35···C1vi3.537 (3)H32···H22.0100
C35···C2vi3.325 (3)H32···H55x2.4100
C36···O1viii3.386 (3)H32···O1v2.9200
C36···C2vi3.554 (3)H33···O16vii2.5800
C51···O173.329 (2)H34···C55vii2.9700
C53···C17viii3.597 (4)H36···O1viii2.7400
C56···C163.368 (4)H36···C42.5700
C56···O16iii3.308 (3)H36···H4A2.5700
C2···H52.9500H36···H4B2.1700
C2···H322.6100H53···C35ix2.9200
C4···H362.5700H55···H32xi2.4100
C6···H562.7300H55···O1iii2.8200
C16···H18C3.0300H56···C62.7300
C32···H22.5600H56···H62.1400
C35···H53ix2.9200H56···O16iii2.4500
C36···H4B2.6400
C16—O17—C17118.4 (2)C3—C4—H4B109.00
O1—C1—C2122.0 (2)C5—C4—H4A109.00
O1—C1—C6120.5 (2)C5—C4—H4B109.00
C2—C1—C6117.5 (2)H4A—C4—H4B108.00
C1—C2—C3124.1 (2)C4—C5—H5108.00
C2—C3—C4120.14 (18)C6—C5—H5108.00
C2—C3—C31121.88 (19)C51—C5—H5108.00
C4—C3—C31117.98 (15)C1—C6—H6108.00
C3—C4—C5112.45 (15)C5—C6—H6108.00
C4—C5—C6110.44 (15)C16—C6—H6108.00
C4—C5—C51111.92 (15)O17—C17—H17A109.00
C6—C5—C51111.38 (16)O17—C17—H17B109.00
C1—C6—C5111.37 (17)C18—C17—H17A109.00
C1—C6—C16110.36 (17)C18—C17—H17B109.00
C5—C6—C16111.41 (16)H17A—C17—H17B108.00
O16—C16—O17124.3 (2)C17—C18—H18A109.00
O16—C16—C6124.9 (2)C17—C18—H18B109.00
O17—C16—C6110.76 (19)C17—C18—H18C109.00
O17—C17—C18111.0 (3)H18A—C18—H18B109.00
C3—C31—C32120.76 (18)H18A—C18—H18C109.00
C3—C31—C36121.43 (19)H18B—C18—H18C109.00
C32—C31—C36117.8 (2)C31—C32—H32119.00
C31—C32—C33121.0 (2)C33—C32—H32120.00
C32—C33—C34120.5 (2)C32—C33—H33120.00
C33—C34—C35119.6 (2)C34—C33—H33120.00
C34—C35—C36120.5 (2)C33—C34—H34120.00
C31—C36—C35120.7 (2)C35—C34—H34120.00
C5—C51—C52122.81 (18)C34—C35—H35120.00
C5—C51—C56120.49 (17)C36—C35—H35120.00
C52—C51—C56116.7 (2)C31—C36—H36120.00
Cl2—C52—C51120.13 (18)C35—C36—H36120.00
Cl2—C52—C53118.07 (16)C52—C53—H53120.00
C51—C52—C53121.8 (2)C54—C53—H53120.00
C52—C53—C54119.7 (2)C53—C54—H54120.00
C53—C54—C55119.9 (3)C55—C54—H54120.00
C54—C55—C56120.2 (3)C54—C55—H55120.00
C51—C56—C55121.7 (2)C56—C55—H55120.00
C1—C2—H2118.00C51—C56—H56119.00
C3—C2—H2118.00C55—C56—H56119.00
C3—C4—H4A109.00
C17—O17—C16—O16−3.1 (4)C6—C5—C51—C52134.2 (2)
C17—O17—C16—C6174.6 (2)C6—C5—C51—C56−45.8 (2)
C16—O17—C17—C18−96.6 (3)C1—C6—C16—O16−111.0 (3)
O1—C1—C2—C3176.5 (2)C1—C6—C16—O1771.4 (2)
C6—C1—C2—C3−0.3 (3)C5—C6—C16—O16124.8 (2)
O1—C1—C6—C5155.26 (19)C5—C6—C16—O17−52.9 (2)
O1—C1—C6—C1631.0 (3)C3—C31—C32—C33−178.6 (2)
C2—C1—C6—C5−27.9 (2)C36—C31—C32—C331.3 (4)
C2—C1—C6—C16−152.18 (18)C3—C31—C36—C35178.79 (18)
C1—C2—C3—C42.1 (3)C32—C31—C36—C35−1.1 (3)
C1—C2—C3—C31−177.22 (18)C31—C32—C33—C34−0.4 (4)
C2—C3—C4—C524.9 (2)C32—C33—C34—C35−0.7 (4)
C31—C3—C4—C5−155.82 (16)C33—C34—C35—C360.9 (3)
C2—C3—C31—C32−13.2 (3)C34—C35—C36—C310.1 (3)
C2—C3—C31—C36166.89 (19)C5—C51—C52—Cl23.0 (3)
C4—C3—C31—C32167.5 (2)C5—C51—C52—C53−178.1 (2)
C4—C3—C31—C36−12.4 (3)C56—C51—C52—Cl2−176.99 (18)
C3—C4—C5—C6−52.1 (2)C56—C51—C52—C531.9 (3)
C3—C4—C5—C51−176.77 (15)C5—C51—C56—C55178.7 (2)
C4—C5—C6—C153.2 (2)C52—C51—C56—C55−1.3 (3)
C4—C5—C6—C16176.93 (17)Cl2—C52—C53—C54178.0 (2)
C51—C5—C6—C1178.25 (15)C51—C52—C53—C54−0.9 (4)
C51—C5—C6—C16−58.1 (2)C52—C53—C54—C55−0.7 (4)
C4—C5—C51—C52−101.6 (2)C53—C54—C55—C561.3 (4)
C4—C5—C51—C5678.3 (2)C54—C55—C56—C51−0.3 (4)

Symmetry codes: (i) −x, −y, −z+1; (ii) x−1, y, z; (iii) −x, −y+1, −z; (iv) x−1, y+1, z; (v) −x, −y, −z; (vi) −x+1, −y, −z; (vii) x+1, y−1, z; (viii) x+1, y, z; (ix) −x+1, −y, −z+1; (x) x, y−1, z; (xi) x, y+1, z.

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
C17—H17A···Cg1ii0.972.893.538 (3)125
C5—H5···Cl20.982.563.0843 (19)114
C33—H33···O16vii0.932.583.296 (3)134
C56—H56···O16iii0.932.453.308 (3)154

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

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: WN2298).

References

  • Bruker (2004). APEX2, SAINT-NT and SADABS Bruker AXS Inc., Madison, Wisconsin, USA.
  • Cokcer, W., Grayson, D. H. & Shannon, P. V. R. (1995). J. Chem. Soc. Perkin Trans. 1, pp. 1153–1162.
  • Farrugia, L. J. (1997). J. Appl. Cryst.30, 565.
  • Friedrich, M., Meichle, W., Bernhard, H., Rihs, G. & Otto, H.-H. (2006). Archiv Pharm (Weinheim, Ger.), 329, 361–370. [PubMed]
  • Guzei, I. A. (2004). J. Chem. Crystallogr.34, 181–184.
  • Pandey, S. C., Singh, S. S., Patro, B. & Ghosh, A. C. (2004). Indian J. Chem. Sect. B, 43, 2705–2707.
  • Rebacz, B., Larsen, T. O., Clausen, M. H., Ronnest, M. H., Löffler, H., Ho, A. D. & Krämer, A. (2007). Cancer Res 67, 6342–6350. [PubMed]
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Shishkina, S. V., Solomovich, E. V., Shishkin, O. V., Kutulya, L. A. & Vashchenko, V. V. (2002). J. Struct. Chem.43, 330–337.
  • Spek, A. L. (2003). J. Appl. Cryst.36, 7–13.

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