(2E,6E)-2,6-Bis(2,6-dichloro­benzyl­idene)­cyclo­hexa­none

Mahdavinia, G.H.; Mirzazadeh, M.; Amani, V.; Notash, B.

doi:10.1107/S1600536812006629

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 68| Part 3| March 2012| Page o778

doi:10.1107/S1600536812006629

Open

access

(2E,6E)-2,6-Bis(2,6-dichlorobenzylidene)cyclohexanone

Gholam Hossein Mahdavinia,^a ^* Maryam Mirzazadeh,^a Vahid Amani ^b and Behrouz Notash ^c

^aDepartment of Chemistry, Marvdasht Branch, Islamic Azad University, Marvdasht, Iran, ^bDepartment of Chemistry, Shahre-Rey Branch, Islamic Azad University, Tehran, Iran, and ^cDepartment of Chemistry, Shahid Beheshti University, G.C., Evin, Tehran 1983963113, Iran
^*Correspondence e-mail: hmahdavinia@gmail.com

(Received 6 February 2012; accepted 14 February 2012; online 17 February 2012)

The title compound, C₂₀H₁₄Cl₄O, was prepared by the reaction of 2,6-dichlorobenzaldehyde and cyclohexanone. In the molecule, the central cyclohexanone ring adopts an envelope conformation, while the terminal benzene rings make a dihedral angle of 57.87 (9)°.

Related literature

For background and applications of arylidene cycloalkanones, see: Deli et al. (1984 ); Nakano et al. (1987 ); Kawamata et al. (1996 ); Dimmock et al. (2003 ); Raj et al. (2003 ); Gangadhara (1995 ). For related structures, see: Yu et al. (2000 ); Zhou (2007 ).

Experimental

Crystal data

C₂₀H₁₄Cl₄O
M_r = 412.11
Orthorhombic, P n a 2₁
a = 17.917 (4) Å
b = 7.3094 (15) Å
c = 14.093 (3) Å
V = 1845.7 (7) Å³
Z = 4
Mo Kα radiation
μ = 0.65 mm⁻¹
T = 120 K
0.6 × 0.35 × 0.33 mm

Data collection

Stoe IPDS 2T diffractometer
13510 measured reflections
4946 independent reflections
4682 reflections with I > 2σ(I)
R_int = 0.043

Refinement

R[F² > 2σ(F²)] = 0.031
wR(F²) = 0.071
S = 1.04
4946 reflections
226 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.25 e Å⁻³
Δρ_min = −0.20 e Å⁻³
Absolute structure: Flack (1983 ), 2369 Friedel pairs
Flack parameter: 0.01 (4)

Data collection: X-AREA (Stoe & Cie, 2005 ); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536812006629/xu5466sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812006629/xu5466Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536812006629/xu5466Isup3.cml

checkCIF report

Comment top

Cross-aldol condensation of aromatic aldehydes with cyclic ketones is an important protocol for the synthesis of arylidene cycloalkanones, which are very important precursors to potentially bioactive pyrimidine derivates (Deli et al., 1984), intermediates for agrochemical, pharmaceuticals and perfumes (Nakano et al., 1987), new organic material for nonlinear optical applications (Kawamata et al., 1996), cytotoxic analogous (Dimmock et al., 2003), bis-spiropyrrolidines (Raj et al., 2003) and the units of liquid crystalline polymers (Gangadhara, 1995). Usually, this condensation process is catalyzed by strong acid or base.

In the molecule of the title compound, (Fig. 1), the bond lengths and angles are within normal ranges (Yu et al., 2000; Zhou, 2007). A dihedral angle of 57.87 (9) A is found between the mean planes of the two benzene rings.

Related literature top

For background and applications of arylidene cycloalkanones, see: Deli et al. (1984); Nakano et al. (1987); Kawamata et al. (1996); Dimmock et al. (2003); Raj et al. (2003); Gangadhara (1995). For related structures, see: Yu et al. (2000); Zhou (2007).

Experimental top

To a 10 ml solution of KOH (0.11 g) in ethanol at 313 K in a round bottom flask, cyclohexanone (5.0 mmol, 0.50 g) and 2,6-dichlorobenzaldehyde (10 mmol, 1.75 g) was added and the mixture was stirred for 2 min. The resulting product was then isolated by simple filtration from the reaction mixture and given washings with water to remove any trace of KOH remaining on the product. Yellow crystals, yield 97%, 1.98 g, m. p. 455–458 K.

Computing details top

Data collection: X-AREA (Stoe & Cie, 2005); cell refinement: X-AREA (Stoe & Cie, 2005); data reduction: X-RED32 (Stoe & Cie, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

Fig. 1. The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.

(2E,6E)-2,6-Bis(2,6-dichlorobenzylidene)cyclohexanone top

Crystal data top

C₂₀H₁₄Cl₄O	F(000) = 840
M_r = 412.11	D_x = 1.483 Mg m⁻³
Orthorhombic, Pna2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2c -2n	Cell parameters from 4949 reflections
a = 17.917 (4) Å	θ = 2.3–29.2°
b = 7.3094 (15) Å	µ = 0.65 mm⁻¹
c = 14.093 (3) Å	T = 120 K
V = 1845.7 (7) Å³	Needle, yellow
Z = 4	0.6 × 0.35 × 0.33 mm

Data collection top

Stoe IPDS 2T diffractometer	4682 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.043
Graphite monochromator	θ_max = 29.2°, θ_min = 2.3°
rotation method scans	h = −24→24
13510 measured reflections	k = −8→10
4946 independent reflections	l = −19→19

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.031	H-atom parameters constrained
wR(F²) = 0.071	w = 1/[σ²(F_o²) + (0.0318P)² + 0.5994P] where P = (F_o² + 2F_c²)/3
S = 1.04	(Δ/σ)_max = 0.001
4946 reflections	Δρ_max = 0.25 e Å⁻³
226 parameters	Δρ_min = −0.20 e Å⁻³
1 restraint	Absolute structure: Flack (1983), 2369 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.01 (4)

Crystal data top

C₂₀H₁₄Cl₄O	V = 1845.7 (7) Å³
M_r = 412.11	Z = 4
Orthorhombic, Pna2₁	Mo Kα radiation
a = 17.917 (4) Å	µ = 0.65 mm⁻¹
b = 7.3094 (15) Å	T = 120 K
c = 14.093 (3) Å	0.6 × 0.35 × 0.33 mm

Data collection top

Stoe IPDS 2T diffractometer	4682 reflections with I > 2σ(I)
13510 measured reflections	R_int = 0.043
4946 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.031	H-atom parameters constrained
wR(F²) = 0.071	Δρ_max = 0.25 e Å⁻³
S = 1.04	Δρ_min = −0.20 e Å⁻³
4946 reflections	Absolute structure: Flack (1983), 2369 Friedel pairs
226 parameters	Absolute structure parameter: 0.01 (4)
1 restraint

Special details top

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 (Å²) top

	x	y	z	U_iso*/U_eq
Cl1	0.23181 (3)	1.40628 (7)	0.99333 (3)	0.03179 (11)
Cl3	−0.14648 (3)	0.88978 (7)	0.82912 (3)	0.03028 (10)
Cl4	0.05216 (3)	0.35099 (7)	0.89917 (4)	0.03460 (11)
Cl2	0.30403 (3)	0.77001 (7)	1.16748 (4)	0.03902 (13)
C12	0.04419 (9)	0.8310 (2)	0.91901 (11)	0.0196 (3)
O1	0.04467 (7)	0.94480 (19)	1.07669 (9)	0.0237 (3)
C6	0.27374 (10)	1.0891 (2)	1.07795 (12)	0.0211 (3)
C13	0.07918 (9)	0.9234 (2)	1.00226 (12)	0.0185 (3)
C7	0.19499 (9)	1.0268 (2)	1.07289 (12)	0.0199 (3)
H7	0.1686	1.0178	1.1295	0.024*
C9	0.19554 (9)	0.9844 (3)	0.89597 (12)	0.0253 (3)
H9A	0.2490	0.9679	0.9032	0.030*
H9B	0.1872	1.1026	0.8666	0.030*
C15	−0.05043 (9)	0.6110 (2)	0.85940 (12)	0.0209 (3)
C5	0.32884 (10)	0.9818 (3)	1.12039 (12)	0.0252 (4)
C18	−0.11451 (11)	0.3989 (3)	0.71361 (15)	0.0317 (4)
H18	−0.1354	0.3295	0.6651	0.038*
C8	0.15938 (9)	0.9827 (2)	0.99274 (12)	0.0186 (3)
C1	0.29745 (11)	1.2584 (3)	1.04280 (12)	0.0253 (4)
C16	−0.02454 (10)	0.4355 (3)	0.83722 (14)	0.0246 (3)
C10	0.16500 (10)	0.8350 (3)	0.83127 (13)	0.0278 (4)
H10A	0.1873	0.8457	0.7688	0.033*
H10B	0.1777	0.7157	0.8568	0.033*
C19	−0.14239 (10)	0.5721 (3)	0.73292 (14)	0.0281 (4)
H19	−0.1820	0.6191	0.6979	0.034*
C11	0.08055 (10)	0.8530 (3)	0.82365 (12)	0.0260 (4)
H11A	0.0681	0.9721	0.7978	0.031*
H11B	0.0615	0.7605	0.7806	0.031*
C3	0.42366 (10)	1.2027 (3)	1.08876 (13)	0.0318 (4)
H3	0.4733	1.2393	1.0916	0.038*
C14	−0.01489 (9)	0.7245 (2)	0.93404 (12)	0.0211 (3)
H14	−0.0350	0.7210	0.9948	0.025*
C20	−0.11038 (10)	0.6741 (3)	0.80531 (12)	0.0222 (3)
C17	−0.05563 (11)	0.3289 (3)	0.76625 (15)	0.0295 (4)
H17	−0.0373	0.2122	0.7541	0.035*
C4	0.40302 (11)	1.0347 (3)	1.12538 (14)	0.0296 (4)
H4	0.4384	0.9584	1.1530	0.036*
C2	0.37123 (11)	1.3166 (3)	1.04810 (13)	0.0298 (4)
H2	0.3850	1.4306	1.0246	0.036*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cl1	0.0347 (2)	0.0280 (2)	0.0326 (2)	−0.00606 (18)	−0.00506 (19)	0.0103 (2)
Cl3	0.0346 (2)	0.0290 (2)	0.0272 (2)	0.00852 (18)	−0.00735 (18)	−0.00764 (19)
Cl4	0.0329 (2)	0.0303 (2)	0.0406 (3)	0.00904 (18)	−0.0048 (2)	−0.0030 (2)
Cl2	0.0393 (2)	0.0295 (2)	0.0483 (3)	−0.0027 (2)	−0.0170 (2)	0.0103 (2)
C12	0.0205 (7)	0.0212 (8)	0.0172 (7)	0.0006 (6)	−0.0003 (6)	−0.0023 (6)
O1	0.0229 (6)	0.0316 (7)	0.0167 (5)	−0.0022 (5)	0.0025 (4)	−0.0034 (5)
C6	0.0233 (7)	0.0252 (8)	0.0147 (6)	−0.0025 (6)	−0.0014 (6)	−0.0006 (6)
C13	0.0185 (7)	0.0214 (7)	0.0157 (7)	0.0020 (6)	0.0008 (6)	0.0017 (6)
C7	0.0214 (7)	0.0217 (7)	0.0166 (7)	−0.0015 (6)	−0.0011 (6)	0.0020 (6)
C9	0.0218 (8)	0.0344 (10)	0.0197 (7)	−0.0056 (7)	0.0038 (7)	−0.0032 (8)
C15	0.0188 (7)	0.0219 (8)	0.0219 (7)	−0.0041 (6)	0.0023 (6)	−0.0011 (6)
C5	0.0273 (9)	0.0279 (9)	0.0204 (8)	−0.0009 (7)	−0.0027 (7)	−0.0023 (7)
C18	0.0259 (9)	0.0345 (10)	0.0348 (10)	−0.0081 (8)	0.0025 (7)	−0.0151 (9)
C8	0.0196 (7)	0.0193 (7)	0.0169 (6)	−0.0001 (6)	0.0001 (6)	0.0010 (6)
C1	0.0267 (8)	0.0313 (9)	0.0179 (7)	−0.0039 (7)	−0.0008 (6)	0.0017 (7)
C16	0.0228 (7)	0.0228 (8)	0.0283 (9)	−0.0013 (6)	0.0026 (7)	−0.0026 (7)
C10	0.0276 (8)	0.0360 (10)	0.0197 (7)	−0.0038 (7)	0.0050 (7)	−0.0068 (8)
C19	0.0233 (8)	0.0340 (10)	0.0270 (9)	−0.0018 (7)	−0.0015 (7)	−0.0090 (8)
C11	0.0289 (8)	0.0331 (10)	0.0160 (7)	−0.0077 (7)	0.0011 (7)	−0.0018 (7)
C3	0.0220 (8)	0.0518 (12)	0.0216 (8)	−0.0093 (8)	0.0008 (7)	−0.0069 (8)
C14	0.0212 (7)	0.0233 (8)	0.0187 (7)	−0.0006 (7)	−0.0001 (6)	−0.0014 (6)
C20	0.0217 (8)	0.0232 (8)	0.0216 (8)	−0.0014 (7)	0.0017 (6)	−0.0040 (6)
C17	0.0281 (9)	0.0241 (9)	0.0362 (10)	−0.0048 (7)	0.0066 (8)	−0.0085 (8)
C4	0.0232 (8)	0.0412 (11)	0.0243 (8)	0.0021 (8)	−0.0063 (7)	−0.0062 (8)
C2	0.0299 (9)	0.0386 (10)	0.0210 (8)	−0.0137 (8)	0.0032 (7)	0.0017 (8)

Geometric parameters (Å, º) top

Cl1—C1	1.743 (2)	C5—C4	1.386 (3)
Cl3—C20	1.7370 (19)	C18—C17	1.388 (3)
Cl4—C16	1.7414 (19)	C18—C19	1.388 (3)
Cl2—C5	1.742 (2)	C18—H18	0.9300
C12—C14	1.331 (2)	C1—C2	1.391 (3)
C12—C13	1.492 (2)	C16—C17	1.385 (3)
C12—C11	1.502 (2)	C10—C11	1.523 (3)
O1—C13	1.228 (2)	C10—H10A	0.9700
C6—C5	1.396 (3)	C10—H10B	0.9700
C6—C1	1.399 (3)	C19—C20	1.388 (2)
C6—C7	1.484 (2)	C19—H19	0.9300
C13—C8	1.507 (2)	C11—H11A	0.9700
C7—C8	1.337 (2)	C11—H11B	0.9700
C7—H7	0.9300	C3—C2	1.380 (3)
C9—C8	1.510 (2)	C3—C4	1.382 (3)
C9—C10	1.524 (3)	C3—H3	0.9300
C9—H9A	0.9700	C14—H14	0.9300
C9—H9B	0.9700	C17—H17	0.9300
C15—C20	1.396 (2)	C4—H4	0.9300
C15—C16	1.399 (3)	C2—H2	0.9300
C15—C14	1.483 (2)

C14—C12—C13	118.29 (15)	C15—C16—Cl4	118.34 (14)
C14—C12—C11	123.35 (15)	C11—C10—C9	109.69 (15)
C13—C12—C11	118.23 (14)	C11—C10—H10A	109.7
C5—C6—C1	115.73 (17)	C9—C10—H10A	109.7
C5—C6—C7	121.37 (17)	C11—C10—H10B	109.7
C1—C6—C7	122.89 (16)	C9—C10—H10B	109.7
O1—C13—C12	121.19 (15)	H10A—C10—H10B	108.2
O1—C13—C8	121.32 (16)	C18—C19—C20	119.04 (18)
C12—C13—C8	117.45 (14)	C18—C19—H19	120.5
C8—C7—C6	124.63 (15)	C20—C19—H19	120.5
C8—C7—H7	117.7	C12—C11—C10	111.02 (15)
C6—C7—H7	117.7	C12—C11—H11A	109.4
C8—C9—C10	112.35 (15)	C10—C11—H11A	109.4
C8—C9—H9A	109.1	C12—C11—H11B	109.4
C10—C9—H9A	109.1	C10—C11—H11B	109.4
C8—C9—H9B	109.1	H11A—C11—H11B	108.0
C10—C9—H9B	109.1	C2—C3—C4	120.58 (18)
H9A—C9—H9B	107.9	C2—C3—H3	119.7
C20—C15—C16	115.85 (16)	C4—C3—H3	119.7
C20—C15—C14	122.20 (16)	C12—C14—C15	123.77 (15)
C16—C15—C14	121.93 (16)	C12—C14—H14	118.1
C4—C5—C6	122.88 (19)	C15—C14—H14	118.1
C4—C5—Cl2	118.28 (15)	C19—C20—C15	122.83 (18)
C6—C5—Cl2	118.83 (14)	C19—C20—Cl3	118.41 (14)
C17—C18—C19	120.36 (18)	C15—C20—Cl3	118.76 (13)
C17—C18—H18	119.8	C16—C17—C18	118.97 (18)
C19—C18—H18	119.8	C16—C17—H17	120.5
C7—C8—C13	116.69 (15)	C18—C17—H17	120.5
C7—C8—C9	123.82 (15)	C3—C4—C5	119.07 (19)
C13—C8—C9	119.47 (14)	C3—C4—H4	120.5
C2—C1—C6	122.69 (18)	C5—C4—H4	120.5
C2—C1—Cl1	118.25 (16)	C3—C2—C1	119.02 (19)
C6—C1—Cl1	119.03 (14)	C3—C2—H2	120.5
C17—C16—C15	122.94 (18)	C1—C2—H2	120.5
C17—C16—Cl4	118.69 (15)

C14—C12—C13—O1	−20.1 (3)	C14—C15—C16—Cl4	−0.5 (2)
C11—C12—C13—O1	163.96 (17)	C8—C9—C10—C11	55.7 (2)
C14—C12—C13—C8	157.57 (16)	C17—C18—C19—C20	0.2 (3)
C11—C12—C13—C8	−18.4 (2)	C14—C12—C11—C10	−132.96 (18)
C5—C6—C7—C8	−112.5 (2)	C13—C12—C11—C10	42.8 (2)
C1—C6—C7—C8	68.8 (3)	C9—C10—C11—C12	−61.2 (2)
C1—C6—C5—C4	−2.0 (3)	C13—C12—C14—C15	−173.89 (16)
C7—C6—C5—C4	179.24 (17)	C11—C12—C14—C15	1.8 (3)
C1—C6—C5—Cl2	179.18 (13)	C20—C15—C14—C12	−92.9 (2)
C7—C6—C5—Cl2	0.4 (2)	C16—C15—C14—C12	85.4 (2)
C6—C7—C8—C13	−179.65 (16)	C18—C19—C20—C15	0.7 (3)
C6—C7—C8—C9	2.1 (3)	C18—C19—C20—Cl3	−179.49 (15)
O1—C13—C8—C7	12.3 (2)	C16—C15—C20—C19	−0.8 (3)
C12—C13—C8—C7	−165.39 (16)	C14—C15—C20—C19	177.55 (17)
O1—C13—C8—C9	−169.41 (17)	C16—C15—C20—Cl3	179.37 (13)
C12—C13—C8—C9	12.9 (2)	C14—C15—C20—Cl3	−2.3 (2)
C10—C9—C8—C7	146.11 (18)	C15—C16—C17—C18	0.8 (3)
C10—C9—C8—C13	−32.1 (2)	Cl4—C16—C17—C18	−176.99 (15)
C5—C6—C1—C2	0.9 (3)	C19—C18—C17—C16	−0.9 (3)
C7—C6—C1—C2	179.69 (17)	C2—C3—C4—C5	0.2 (3)
C5—C6—C1—Cl1	−177.17 (13)	C6—C5—C4—C3	1.4 (3)
C7—C6—C1—Cl1	1.6 (2)	Cl2—C5—C4—C3	−179.70 (14)
C20—C15—C16—C17	0.1 (3)	C4—C3—C2—C1	−1.2 (3)
C14—C15—C16—C17	−178.32 (17)	C6—C1—C2—C3	0.6 (3)
C20—C15—C16—Cl4	177.86 (13)	Cl1—C1—C2—C3	178.73 (14)

Experimental details

Crystal data
Chemical formula	C₂₀H₁₄Cl₄O
M_r	412.11
Crystal system, space group	Orthorhombic, Pna2₁
Temperature (K)	120
a, b, c (Å)	17.917 (4), 7.3094 (15), 14.093 (3)
V (Å³)	1845.7 (7)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.65
Crystal size (mm)	0.6 × 0.35 × 0.33

Data collection
Diffractometer	Stoe IPDS 2T diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	13510, 4946, 4682
R_int	0.043
(sin θ/λ)_max (Å⁻¹)	0.685

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.031, 0.071, 1.04
No. of reflections	4946
No. of parameters	226
No. of restraints	1
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.25, −0.20
Absolute structure	Flack (1983), 2369 Friedel pairs
Absolute structure parameter	0.01 (4)

Computer programs: X-AREA (Stoe & Cie, 2005), X-RED32 (Stoe & Cie, 2005), SHELXTL (Sheldrick, 2008).

Acknowledgements

We are grateful to the Islamic Azad University, Marvdasht Branch, for financial support.

References

Deli, J., Lorand, T., Szabo, D. & Foldesi, A. (1984). Pharmazie, 39, 539–540. CAS PubMed Web of Science Google Scholar
Dimmock, J. R., Padmanilayam, M. P., Zello, G. A., Nienaber, K. H., Allen, T. M., Santos, C. L., Clercq, E. D., Balzarini, J., Manavathu, E. K. & Stables, J. P. (2003). Eur. J. Med. Chem. 38, 169–177. Web of Science CrossRef PubMed CAS Google Scholar
Flack, H. D. (1983). Acta Cryst. A39, 876–881. CrossRef CAS Web of Science IUCr Journals Google Scholar
Gangadhara, K. K. (1995). Polymer, 36, 1903–1910. CrossRef CAS Google Scholar
Kawamata, J., Inoue, K., Inabe, T., Kiguchi, M., Kato, M. & Taniguchi, Y. (1996). Chem. Phys. Lett. 249, 29–34. CrossRef CAS Web of Science Google Scholar
Nakano, T., Irifune, S. & Inada, A. (1987). J. Org. Chem. 52, 2239–2244. CrossRef CAS Web of Science Google Scholar
Raj, A. A., Raghunathan, R., Sridevi Kumari, M. R. & Raman, N. (2003). Bioorg. Med. Chem. 11, 407–419. Web of Science CrossRef PubMed CAS Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Stoe & Cie (2005). X-AREA and X-RED32. Stoe & Cie, Darmstadt, Germany Google Scholar
Yu, R. C., Yakimansky, A. V., Kothe, H., Voigt-Martin, I. G., Schollmeyer, D., Jansen, J., Zandbergen, H. & Tenkovtsev, A. V. (2000). Acta Cryst. A56, 436–450. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Zhou, L.-Y. (2007). Acta Cryst. E63, o3113. Web of Science CSD CrossRef IUCr Journals Google Scholar