5,8-Dibromo-15,18-dimeth­oxy-2,11-dithia­[3.3]paracyclo­phane

Jin, G.; Lu, Y.

doi:10.1107/S1600536810029053

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 66| Part 8| August 2010| Page o2144

https://doi.org/10.1107/S1600536810029053

Open

access

5,8-Dibromo-15,18-dimethoxy-2,11-dithia[3.3]paracyclophane

Guojun Jin ^a ^* and Yinghui Lu ^a

^aKey Laboratory of Pesticides and Chemical Biology of the Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, People's Republic of China
^*Correspondence e-mail: jgj6100449@163.com

(Received 1 July 2010; accepted 21 July 2010; online 31 July 2010)

In the title compound [systematic name: 1²,1⁵-dibromo-5²,5⁵-dimethoxy-2,7-dithia-1,5(1,4)-dibenzenaoctaphane], C₁₈H₁₈Br₂O₂S₂, the dihedral angle between the aromatic rings is 0.6 (2)° and their centroid separation is 3.251 (2) Å, indicating that a trans-annular π–π interaction occurs. The dimethoxy and dibromo substituents are located at crossed positions because of the electronic and the steric nature of the substituents.

Related literature

For the preparation of the title compound, see: Kay & Baek (1997 ); Xu et al. (2008 ). For paracyclophane and its derivatives, see: Clément et al. (2009 ); Wang et al. (2006 ); Yamamoto et al. (1997 ). For studies on the benzene dimer of [2.2]paracyclophane, see: Ball et al. (2004 ); Dahmen & Bräse (2002 ); Rowlands (2008 ); Valentini et al. (2008 ). For studies of [3.3]paracyclophane, see: Wang et al. (2004 ).

Experimental

Crystal data

C₁₈H₁₈Br₂O₂S₂
M_r = 490.26
Monoclinic, P 2₁ /n
a = 8.9576 (8) Å
b = 16.2291 (14) Å
c = 13.0251 (11) Å
β = 103.240 (1)°
V = 1843.2 (3) Å³
Z = 4
Mo Kα radiation
μ = 4.63 mm⁻¹
T = 298 K
0.16 × 0.12 × 0.10 mm

Data collection

Bruker SMART CCD area-detector diffractometer
12800 measured reflections
4475 independent reflections
2812 reflections with I > 2σ(I)
R_int = 0.126

Refinement

R[F² > 2σ(F²)] = 0.059
wR(F²) = 0.151
S = 0.95
4475 reflections
219 parameters
H-atom parameters constrained
Δρ_max = 1.00 e Å⁻³
Δρ_min = −1.27 e Å⁻³

Data collection: SMART (Bruker, 1997 ); cell refinement: SAINT (Bruker, 1999 ); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, New_Global_Publ_Block. DOI: https://doi.org/10.1107/S1600536810029053/si2274sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810029053/si2274Isup2.hkl

checkCIF report

Comment top

Various studies on the benzene dimer of [2.2]paracyclophane have focused on the face-to-face stacking (Rowlands, 2008),it is known to play a significant role in chiral catalysis (Dahmen & Bräse, 2002), molecular electronics (Ball et al.,2004), and organic solar cells (Valentini et al.,2008). However, the [3.3]paracyclophane have received less attention (Wang et al.2004). In our research, we have synthetized a series of novel dithia[3.3]paracyclophane. The inter plane distance of the two benzene rings of 3.251Å is less than the normal packing distance of aromatic rings in organic aromatic molecules(3.4°), thus suggesting probable transannular π-π interaction.

For the preparation of the title compound, see: Kay & Baek (1997); Xu et al. (2008); for the paracyclophanes and its derivatives, see: Clément et al. (2009); Wang et al. (2006); Yamamoto et al. (1997).

Related literature top

For the preparation of the title compound, see: Kay & Baek (1997); Xu et al. (2008). For paracyclophane and its derivatives, see: Clément et al. (2009); Wang et al. (2006); Yamamoto et al. (1997). For studies on the benzene dimer of [2.2]paracyclophane, see: Ball et al. (2004); Dahmen & Bräse (2002); Rowlands (2008); Valentini et al. (2008). For studies of [3.3]paracyclophane, see: Wang et al. (2004).

Experimental top

A solution with equimolar amounts of 2,5-dibromo-1,4-bis(mercaptomethyl)benzene (3.26 g,10 mmol) and 1,4-dibromomethyl-2,5-dimethoxybenzene(3.22 g,10 mmol) in degassed THF(500 mL) was added dropwise under N₂ over 12 h to a refluxing solution of potassium carbonate(6.9 g,50 mmol) in EtOH(1.5L). After an additional 2 h at the reflux temperature (353 K), the mixture was cooled and the solvent were removed. The resulting residue was treated with CH₂Cl₂(500 mL) and water(500 mL). The organic phase was separated, the aqueous extracted with CH₂Cl₂ three times. The combined organic layers was dried over Na₂SO₄,then the solvent was removed, and the resulting solid was chromatographed on silica gel using CH₂Cl₂/petroleum ether(1:1,v/v) as eluent. Colourless single crystals of the title compound suitable for X-ray diffraction were obtained by slow evaporation of a dichloromethane/n-hexane(1:30) solution over a period of 5 days.

Structure description top

For the preparation of the title compound, see: Kay & Baek (1997); Xu et al. (2008). For paracyclophane and its derivatives, see: Clément et al. (2009); Wang et al. (2006); Yamamoto et al. (1997). For studies on the benzene dimer of [2.2]paracyclophane, see: Ball et al. (2004); Dahmen & Bräse (2002); Rowlands (2008); Valentini et al. (2008). For studies of [3.3]paracyclophane, see: Wang et al. (2004).

Computing details top

Data collection: SMART (Bruker, 1997); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT (Bruker, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

Fig. 1. Molecular structure of the tite compound with displacement ellipsoids drawn at the 30% probability level.

1²,1⁵-dibromo-5²,5⁵-dimethoxy-2,7-dithia-1,5(1,4)-dibenzenaoctaphane top

Crystal data top

C₁₈H₁₈Br₂O₂S₂	F(000) = 976
M_r = 490.26	D_x = 1.767 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 3885 reflections
a = 8.9576 (8) Å	θ = 2.5–26.9°
b = 16.2291 (14) Å	µ = 4.63 mm⁻¹
c = 13.0251 (11) Å	T = 298 K
β = 103.240 (1)°	Block, colorless
V = 1843.2 (3) Å³	0.16 × 0.12 × 0.10 mm
Z = 4

Data collection top

Bruker SMART CCD area detector diffractometer	2812 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.126
Graphite monochromator	θ_max = 28.3°, θ_min = 2.0°
phi and ω scans	h = −11→11
12800 measured reflections	k = −19→21
4475 independent reflections	l = −15→17

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)] = 0.059	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.151	H-atom parameters constrained
S = 0.95	w = 1/[σ²(F_o²) + (0.0753P)²] where P = (F_o² + 2F_c²)/3
4475 reflections	(Δ/σ)_max = 0.001
219 parameters	Δρ_max = 1.00 e Å⁻³
0 restraints	Δρ_min = −1.27 e Å⁻³

Crystal data top

C₁₈H₁₈Br₂O₂S₂	V = 1843.2 (3) Å³
M_r = 490.26	Z = 4
Monoclinic, P2₁/n	Mo Kα radiation
a = 8.9576 (8) Å	µ = 4.63 mm⁻¹
b = 16.2291 (14) Å	T = 298 K
c = 13.0251 (11) Å	0.16 × 0.12 × 0.10 mm
β = 103.240 (1)°

Data collection top

Bruker SMART CCD area detector diffractometer	2812 reflections with I > 2σ(I)
12800 measured reflections	R_int = 0.126
4475 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.059	0 restraints
wR(F²) = 0.151	H-atom parameters constrained
S = 0.95	Δρ_max = 1.00 e Å⁻³
4475 reflections	Δρ_min = −1.27 e Å⁻³
219 parameters

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
Br1	0.56512 (6)	0.00221 (3)	0.68306 (4)	0.0672 (2)
Br2	1.04343 (6)	0.17844 (3)	0.44267 (4)	0.05796 (19)
C1	0.9651 (5)	0.0721 (2)	0.6001 (3)	0.0383 (9)
C2	0.8556 (5)	0.0352 (2)	0.6428 (3)	0.0414 (9)
H2	0.8858	−0.0067	0.6919	0.050*
C3	0.7037 (5)	0.0569 (2)	0.6166 (3)	0.0421 (9)
C4	0.6510 (5)	0.1210 (2)	0.5448 (3)	0.0426 (9)
C5	0.7568 (5)	0.1535 (2)	0.4937 (3)	0.0419 (9)
H5	0.7248	0.1924	0.4408	0.050*
C6	0.9099 (5)	0.1296 (2)	0.5193 (3)	0.0386 (9)
C7	1.1351 (5)	0.0552 (3)	0.6408 (3)	0.0478 (10)
H7A	1.1921	0.1026	0.6250	0.057*
H7B	1.1630	0.0085	0.6027	0.057*
C8	1.2053 (5)	0.1368 (3)	0.8357 (3)	0.0603 (13)
H8A	1.2330	0.1323	0.9120	0.072*
H8B	1.2865	0.1669	0.8140	0.072*
C9	1.0584 (5)	0.1853 (3)	0.8039 (3)	0.0483 (11)
C10	0.9312 (5)	0.1636 (3)	0.8413 (3)	0.0466 (10)
C11	0.7901 (5)	0.1997 (3)	0.7979 (3)	0.0461 (10)
H11	0.7041	0.1842	0.8220	0.055*
C12	0.7759 (5)	0.2590 (3)	0.7186 (3)	0.0423 (9)
C13	0.9054 (5)	0.2850 (3)	0.6891 (3)	0.0447 (10)
C14	1.0460 (5)	0.2476 (3)	0.7292 (3)	0.0480 (10)
H14	1.1321	0.2642	0.7061	0.058*
C15	0.6193 (5)	0.2917 (3)	0.6623 (4)	0.0519 (11)
H15A	0.6279	0.3141	0.5948	0.062*
H15B	0.5928	0.3368	0.7035	0.062*
C16	0.4926 (5)	0.1575 (3)	0.5276 (4)	0.0531 (11)
H16A	0.4179	0.1132	0.5143	0.064*
H16B	0.4745	0.1922	0.4654	0.064*
C17	0.8336 (7)	0.0803 (4)	0.9594 (4)	0.0767 (16)
H17A	0.7924	0.1276	0.9874	0.115*
H17B	0.8688	0.0411	1.0149	0.115*
H17C	0.7553	0.0555	0.9054	0.115*
C18	1.0126 (6)	0.3817 (3)	0.5888 (4)	0.0703 (14)
H18A	1.0703	0.4095	0.6503	0.106*
H18B	0.9807	0.4208	0.5328	0.106*
H18C	1.0756	0.3402	0.5673	0.106*
O1	0.9536 (4)	0.1039 (2)	0.9173 (2)	0.0666 (9)
O2	0.8860 (4)	0.34533 (19)	0.6119 (2)	0.0584 (8)
S1	1.19297 (14)	0.03433 (8)	0.77929 (9)	0.0601 (3)
S2	0.46307 (13)	0.21831 (8)	0.63885 (10)	0.0559 (3)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br1	0.0566 (3)	0.0782 (4)	0.0670 (4)	−0.0235 (2)	0.0142 (3)	0.0087 (2)
Br2	0.0558 (3)	0.0679 (3)	0.0542 (3)	−0.0029 (2)	0.0209 (2)	0.0073 (2)
C1	0.038 (2)	0.041 (2)	0.0332 (19)	0.0023 (16)	0.0015 (15)	−0.0064 (16)
C2	0.046 (2)	0.039 (2)	0.036 (2)	−0.0006 (18)	0.0028 (17)	0.0016 (17)
C3	0.043 (2)	0.046 (2)	0.036 (2)	−0.0103 (18)	0.0058 (17)	−0.0035 (17)
C4	0.039 (2)	0.048 (2)	0.035 (2)	−0.0046 (18)	−0.0025 (16)	−0.0061 (17)
C5	0.045 (2)	0.050 (2)	0.0287 (19)	−0.0017 (18)	0.0036 (16)	0.0002 (17)
C6	0.041 (2)	0.045 (2)	0.0292 (18)	−0.0044 (17)	0.0055 (16)	−0.0023 (16)
C7	0.043 (2)	0.059 (3)	0.040 (2)	0.005 (2)	0.0048 (18)	−0.0066 (19)
C8	0.041 (3)	0.097 (4)	0.036 (2)	0.002 (2)	−0.0063 (18)	−0.010 (2)
C9	0.036 (2)	0.072 (3)	0.032 (2)	−0.005 (2)	−0.0033 (17)	−0.018 (2)
C10	0.049 (3)	0.064 (3)	0.0253 (19)	0.000 (2)	0.0041 (17)	−0.0072 (18)
C11	0.037 (2)	0.064 (3)	0.039 (2)	−0.0033 (19)	0.0114 (17)	−0.0076 (19)
C12	0.036 (2)	0.051 (2)	0.038 (2)	−0.0044 (18)	0.0059 (16)	−0.0099 (18)
C13	0.043 (2)	0.054 (2)	0.034 (2)	−0.0112 (19)	0.0024 (17)	−0.0136 (18)
C14	0.037 (2)	0.068 (3)	0.037 (2)	−0.011 (2)	0.0034 (16)	−0.018 (2)
C15	0.040 (2)	0.059 (3)	0.056 (3)	−0.003 (2)	0.010 (2)	0.002 (2)
C16	0.032 (2)	0.072 (3)	0.050 (2)	−0.003 (2)	−0.0010 (18)	−0.001 (2)
C17	0.077 (4)	0.100 (4)	0.054 (3)	0.002 (3)	0.017 (3)	0.027 (3)
C18	0.068 (3)	0.069 (3)	0.072 (3)	−0.023 (3)	0.014 (3)	−0.004 (3)
O1	0.055 (2)	0.102 (3)	0.0419 (17)	0.0117 (19)	0.0104 (15)	0.0129 (17)
O2	0.056 (2)	0.0589 (18)	0.058 (2)	−0.0108 (16)	0.0077 (15)	0.0047 (15)
S1	0.0459 (7)	0.0797 (8)	0.0499 (7)	0.0193 (6)	0.0010 (5)	0.0161 (6)
S2	0.0312 (6)	0.0714 (8)	0.0654 (8)	−0.0008 (5)	0.0113 (5)	−0.0028 (6)

Geometric parameters (Å, º) top

Br1—C3	1.889 (4)	C10—C11	1.390 (6)
Br2—C6	1.898 (4)	C11—C12	1.397 (6)
C1—C2	1.372 (6)	C11—H11	0.9300
C1—C6	1.408 (5)	C12—C13	1.369 (6)
C1—C7	1.518 (6)	C12—C15	1.521 (6)
C2—C3	1.371 (6)	C13—O2	1.386 (5)
C2—H2	0.9300	C13—C14	1.388 (6)
C3—C4	1.407 (5)	C14—H14	0.9300
C4—C5	1.382 (6)	C15—S2	1.809 (4)
C4—C16	1.506 (6)	C15—H15A	0.9700
C5—C6	1.390 (6)	C15—H15B	0.9700
C5—H5	0.9300	C16—S2	1.822 (5)
C7—S1	1.792 (4)	C16—H16A	0.9700
C7—H7A	0.9700	C16—H16B	0.9700
C7—H7B	0.9700	C17—O1	1.369 (6)
C8—C9	1.508 (6)	C17—H17A	0.9600
C8—S1	1.812 (5)	C17—H17B	0.9600
C8—H8A	0.9700	C17—H17C	0.9600
C8—H8B	0.9700	C18—O2	1.372 (6)
C9—C10	1.384 (6)	C18—H18A	0.9600
C9—C14	1.389 (6)	C18—H18B	0.9600
C10—O1	1.368 (5)	C18—H18C	0.9600

C2—C1—C6	115.5 (4)	C12—C11—H11	119.6
C2—C1—C7	122.2 (4)	C13—C12—C11	118.7 (4)
C6—C1—C7	122.2 (4)	C13—C12—C15	120.3 (4)
C3—C2—C1	123.3 (4)	C11—C12—C15	120.9 (4)
C3—C2—H2	118.4	C12—C13—O2	116.6 (4)
C1—C2—H2	118.4	C12—C13—C14	120.9 (4)
C2—C3—C4	121.2 (4)	O2—C13—C14	122.3 (4)
C2—C3—Br1	119.0 (3)	C13—C14—C9	120.1 (4)
C4—C3—Br1	119.8 (3)	C13—C14—H14	119.9
C5—C4—C3	116.1 (4)	C9—C14—H14	119.9
C5—C4—C16	120.4 (4)	C12—C15—S2	116.4 (3)
C3—C4—C16	123.4 (4)	C12—C15—H15A	108.2
C4—C5—C6	121.7 (4)	S2—C15—H15A	108.2
C4—C5—H5	119.1	C12—C15—H15B	108.2
C6—C5—H5	119.1	S2—C15—H15B	108.2
C5—C6—C1	121.5 (4)	H15A—C15—H15B	107.3
C5—C6—Br2	117.6 (3)	C4—C16—S2	113.5 (3)
C1—C6—Br2	120.9 (3)	C4—C16—H16A	108.9
C1—C7—S1	114.9 (3)	S2—C16—H16A	108.9
C1—C7—H7A	108.5	C4—C16—H16B	108.9
S1—C7—H7A	108.5	S2—C16—H16B	108.9
C1—C7—H7B	108.5	H16A—C16—H16B	107.7
S1—C7—H7B	108.5	O1—C17—H17A	109.5
H7A—C7—H7B	107.5	O1—C17—H17B	109.5
C9—C8—S1	113.5 (3)	H17A—C17—H17B	109.5
C9—C8—H8A	108.9	O1—C17—H17C	109.5
S1—C8—H8A	108.9	H17A—C17—H17C	109.5
C9—C8—H8B	108.9	H17B—C17—H17C	109.5
S1—C8—H8B	108.9	O2—C18—H18A	109.5
H8A—C8—H8B	107.7	O2—C18—H18B	109.5
C10—C9—C14	119.4 (4)	H18A—C18—H18B	109.5
C10—C9—C8	120.5 (4)	O2—C18—H18C	109.5
C14—C9—C8	119.8 (4)	H18A—C18—H18C	109.5
O1—C10—C9	116.0 (4)	H18B—C18—H18C	109.5
O1—C10—C11	124.2 (4)	C10—O1—C17	119.3 (4)
C9—C10—C11	119.7 (4)	C18—O2—C13	119.4 (4)
C10—C11—C12	120.7 (4)	C7—S1—C8	102.2 (2)
C10—C11—H11	119.6	C15—S2—C16	104.1 (2)

C6—C1—C2—C3	−5.6 (6)	O1—C10—C11—C12	−178.4 (4)
C7—C1—C2—C3	171.5 (4)	C9—C10—C11—C12	−1.5 (6)
C1—C2—C3—C4	−1.6 (6)	C10—C11—C12—C13	−4.2 (6)
C1—C2—C3—Br1	−179.0 (3)	C10—C11—C12—C15	173.1 (4)
C2—C3—C4—C5	7.4 (6)	C11—C12—C13—O2	−178.4 (4)
Br1—C3—C4—C5	−175.2 (3)	C15—C12—C13—O2	4.2 (5)
C2—C3—C4—C16	−168.8 (4)	C11—C12—C13—C14	6.4 (6)
Br1—C3—C4—C16	8.6 (5)	C15—C12—C13—C14	−171.0 (4)
C3—C4—C5—C6	−6.0 (6)	C12—C13—C14—C9	−2.8 (6)
C16—C4—C5—C6	170.4 (4)	O2—C13—C14—C9	−177.7 (3)
C4—C5—C6—C1	−1.2 (6)	C10—C9—C14—C13	−3.0 (6)
C4—C5—C6—Br2	179.7 (3)	C8—C9—C14—C13	171.4 (4)
C2—C1—C6—C5	7.0 (5)	C13—C12—C15—S2	141.2 (3)
C7—C1—C6—C5	−170.2 (4)	C11—C12—C15—S2	−36.0 (5)
C2—C1—C6—Br2	−174.0 (3)	C5—C4—C16—S2	−105.9 (4)
C7—C1—C6—Br2	8.8 (5)	C3—C4—C16—S2	70.2 (5)
C2—C1—C7—S1	−32.5 (5)	C9—C10—O1—C17	178.9 (4)
C6—C1—C7—S1	144.4 (3)	C11—C10—O1—C17	−4.1 (7)
S1—C8—C9—C10	69.9 (5)	C12—C13—O2—C18	171.4 (4)
S1—C8—C9—C14	−104.4 (4)	C14—C13—O2—C18	−13.5 (6)
C14—C9—C10—O1	−177.8 (4)	C1—C7—S1—C8	−80.3 (4)
C8—C9—C10—O1	7.9 (6)	C9—C8—S1—C7	56.6 (4)
C14—C9—C10—C11	5.1 (6)	C12—C15—S2—C16	−76.7 (4)
C8—C9—C10—C11	−169.2 (4)	C4—C16—S2—C15	53.5 (4)

Experimental details

Crystal data
Chemical formula	C₁₈H₁₈Br₂O₂S₂
M_r	490.26
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	298
a, b, c (Å)	8.9576 (8), 16.2291 (14), 13.0251 (11)
β (°)	103.240 (1)
V (Å³)	1843.2 (3)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	4.63
Crystal size (mm)	0.16 × 0.12 × 0.10

Data collection
Diffractometer	Bruker SMART CCD area detector
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	12800, 4475, 2812
R_int	0.126
(sin θ/λ)_max (Å⁻¹)	0.666

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.059, 0.151, 0.95
No. of reflections	4475
No. of parameters	219
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	1.00, −1.27

Computer programs: SMART (Bruker, 1997), SAINT (Bruker, 1999), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Acknowledgements

The authors thank Professor Sheng-Hua Liu for technical assistance with the structure analysis and Dr Xiang-Gao Meng for the data collection.

References

Ball, P. J., Shtoyko, T. R., Bauer, J. A. K., Oldham, W. J. & Connick, W. B. (2004). Inorg. Chem. 43, 622–632. Web of Science CSD CrossRef PubMed CAS Google Scholar
Bruker (1997). SMART. Bruker AXS Inc., Madison, Wiskonsin, USA. Google Scholar
Bruker (1999). SAINT. Bruker AXS Inc., Madison, Wiskonsin, USA. Google Scholar
Clément, S., Guyard, L., Knorr, M., Däschlein, C. & Strohmann, C. (2009). Acta Cryst. E65, o528. Web of Science CSD CrossRef IUCr Journals Google Scholar
Dahmen, S. & Bräse, S. (2002). J. Am. Chem. Soc. 124, 5940–5941. Web of Science CrossRef PubMed CAS Google Scholar
Kay, K. Y. & Baek, Y. G. (1997). Chem. Ber. Rec. 130, 581–584. CrossRef CAS Web of Science Google Scholar
Rowlands, G. J. (2008). Org. Biomol. Chem. 6, 1527–1534. 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
Valentini, L., Marrocchi, A., Seri, M., Mengoni, F., Meloni, F., Taticchi, A. & Kenny, J. M. (2008). Thin Solid Films. 516, 7193–7198. Web of Science CrossRef CAS Google Scholar
Wang, W., Xu, J., Lai, Y. H. & Wang, F. (2004). Macromolecules, 37, 3546–3553. Web of Science CrossRef CAS Google Scholar
Wang, W., Xu, J., Sun, Z., Zhang, X., Lu, Y. & Lai, Y. H. (2006). Macromolecules, 39, 7277–7285. Web of Science CrossRef CAS Google Scholar
Xu, J. W., Wang, W. L., Lin, T. T., Sun, Z.& Lai, Y. H. (2008). Supramol. Chem. 20, 723–730. Web of Science CSD CrossRef CAS Google Scholar
Yamamoto, M., Wu, L. P., Kuroda-Sowa, T., Maekawa, M., Suenaga, Y. & Munakata, M. (1997). Inorg. Chim. Acta, 258, 87–91. CSD CrossRef CAS Web of Science Google Scholar