1,4a,7-Trimethyl-7-vinyl-1,2,3,4,4a,4b,5,6,7,9,10,10a-dodeca­hydro­phenanthrene-1-carboxylic acid

Chen, Y.; Zhao, Z.; Gu, Y.; Wang, Y.

doi:10.1107/S1600536809013233

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 65| Part 5| May 2009| Page o1117

doi:10.1107/S1600536809013233

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1,4a,7-Trimethyl-7-vinyl-1,2,3,4,4a,4b,5,6,7,9,10,10a-dodecahydrophenanthrene-1-carboxylic acid

Yu-xiang Chen,^a Zhen-dong Zhao,^a ^* Yan Gu ^a and Yu-min Wang ^a

^aInstitute of Chemical Industry of Forest Products, Chinese Academy of Forestry, Nanjing, 210042, People's Republic of China
^*Correspondence e-mail: sbkf@tom.com

(Received 8 February 2007; accepted 15 February 2007; online 25 April 2009)

The title compound, pimaric acid, C₂₀H₃₀O₂, was isolated from a mixture of resin acids. There are three rings in the structure. The two cyclohexane rings have classical chair conformations with trans-fused ring junctions. The cyclohexene ring appears as a semi-chair.

Related literature

For physical and spectral data relating to pimaric acid, see: Green et al. (1958 ); Harris & Sanderson (1948 ). For the biological activity of pimaric acid, see: Imaizumi et al. (2002 ); Rubio et al. (2005 ).

Experimental

Crystal data

C₂₀H₃₀O₂
M_r = 302.44
Orthorhombic, P 2₁ 2₁ 2
a = 20.818 (4) Å
b = 10.990 (2) Å
c = 7.7650 (16) Å
V = 1776.6 (6) Å³
Z = 4
Mo Kα radiation
μ = 0.07 mm⁻¹
T = 293 K
0.30 × 0.20 × 0.10 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
Absorption correction: ψ scan (North et al., 1968 ) T_min = 0.979, T_max = 0.993
1862 measured reflections
1862 independent reflections
1231 reflections with I > 2σ(I)
3 standard reflections every 200 reflections intensity decay: 1%

Refinement

R[F² > 2σ(F²)] = 0.065
wR(F²) = 0.188
S = 1.00
1862 reflections
193 parameters
H-atom parameters constrained
Δρ_max = 0.16 e Å⁻³
Δρ_min = −0.17 e Å⁻³

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994 ); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo,1995 ); 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, global. DOI: 10.1107/S1600536809013233/at2757sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809013233/at2757Isup2.hkl

checkCIF report

Comment top

The title compound has been isolated from a mixture of resin acids. It was identified as pimaric acid on the basis of the comparison of its physical and spectral data with literature values (Green et al., 1958; Harris et al., 1948). Pimaric acid exhibits a wide range of biological activities such as trypanocidal activity(Rubio et al., 2005), potent BK channel activity (Imaizumi et al., 2002). Although much attention has been paid to the bioactivities of pimaric acid, the crystal structure of the title compound has not yet been reported.

In this work, we describe the crystal structure of the title compound.

The molecular structure is shown in Fig. 1 and the crystal packing in Fig.2.

The atoms of C5, C6, C7, C8 in the cyclohexene ring and the atom C10 in the conjoint cyclohexane ring are in the same plane. The two methyl groups attached to the cyclohexane rings are in axial positions and in the same direction. The crystal structure is stabilized by O2—H2B···O1 and C12—H12A···O2 hydrogen bongding interactions.

Related literature top

For physical and spectral data relating to pimaric acid, see: Green et al. (1958); Harris & Sanderson (1948). For the biological activity of pimaric acid, see: Imaizumi et al. (2002); Rubio et al. (2005).

Experimental top

A mixture of resin acids and maleic anhydride were dissolved in acetic acid and the solution was refluxed for 4 h. After refluxing the solution was cooled to room temperature and then filtrated. The solvent in the filtrate was distilled away under vacuum and the remainder was dissolved in 1% sodium hydroxide solution. The solution was left standing overnight. The precipitate obtained from the solution was acidified by 5% hydrochloric acid solution and then dissolved in ether. The solution was washed with water until it was neutral, dryed with sodium sulfate and then concentrated. The residue was recrystallized with acetone and the title compound was obtained as colorless solid.

Computing details top

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS (Enraf–Nonius, 1994); data reduction: XCAD4 (Harms & Wocadlo,1995); 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: SHEXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. A view of the molecular structure of (I), showing displacement ellipsoids at the 30% probability level.
	Fig. 2. A view of the packing of the title compound.

1,4a,7-trimethyl-7-vinyl-1,2,3,4,4a,4 b,5,6,7,9,10,10a- dodecahydrophenanthrene-1-carboxylic acid top

Crystal data top

C₂₀H₃₀O₂	D_x = 1.131 Mg m⁻³
M_r = 302.44	Melting point: 490K K
Orthorhombic, P2₁2₁2	Mo Kα radiation, λ = 0.71073 Å
a = 20.818 (4) Å	Cell parameters from 25 reflections
b = 10.990 (2) Å	θ = 9–12°
c = 7.7650 (16) Å	µ = 0.07 mm⁻¹
V = 1776.6 (6) Å³	T = 293 K
Z = 4	Rectangular plate, colorless
F(000) = 664	0.30 × 0.20 × 0.10 mm

Data collection top

Enraf–Nonius CAD-4 diffractometer	1231 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.000
Graphite monochromator	θ_max = 25.3°, θ_min = 2.0°
ω/2θ scans	h = 0→25
Absorption correction: ψ scan (North et al., 1968)	k = 0→13
T_min = 0.979, T_max = 0.993	l = −9→9
1862 measured reflections	3 standard reflections every 200 reflections
1862 independent reflections	intensity decay: 1%

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)] = 0.065	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.188	H-atom parameters constrained
S = 1.00	w = 1/[σ²(F_o²) + (0.1P)² + 0.6P] where P = (F_o² + 2F_c²)/3
1862 reflections	(Δ/σ)_max < 0.001
193 parameters	Δρ_max = 0.16 e Å⁻³
0 restraints	Δρ_min = −0.17 e Å⁻³

Crystal data top

C₂₀H₃₀O₂	V = 1776.6 (6) Å³
M_r = 302.44	Z = 4
Orthorhombic, P2₁2₁2	Mo Kα radiation
a = 20.818 (4) Å	µ = 0.07 mm⁻¹
b = 10.990 (2) Å	T = 293 K
c = 7.7650 (16) Å	0.30 × 0.20 × 0.10 mm

Data collection top

Enraf–Nonius CAD-4 diffractometer	1231 reflections with I > 2σ(I)
Absorption correction: ψ scan (North et al., 1968)	R_int = 0.000
T_min = 0.979, T_max = 0.993	3 standard reflections every 200 reflections
1862 measured reflections	intensity decay: 1%
1862 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.065	0 restraints
wR(F²) = 0.188	H-atom parameters constrained
S = 1.00	Δρ_max = 0.16 e Å⁻³
1862 reflections	Δρ_min = −0.17 e Å⁻³
193 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
O1	0.99697 (17)	0.6536 (3)	0.9540 (7)	0.1009 (15)
O2	0.91875 (17)	0.5243 (3)	0.9640 (8)	0.1170 (19)
H2B	0.9493	0.4772	0.9603	0.176*
C1	0.5623 (5)	0.9204 (9)	0.5670 (15)	0.149 (4)
H1A	0.5421	0.9085	0.6725	0.179*
H1B	0.5589	0.9950	0.5113	0.179*
C2	0.5940 (4)	0.8361 (8)	0.5000 (12)	0.119 (3)
H2A	0.6125	0.8558	0.3947	0.143*
C3	0.5645 (3)	0.6180 (8)	0.4461 (11)	0.124 (3)
H3A	0.5725	0.6340	0.3264	0.186*
H3B	0.5200	0.6321	0.4713	0.186*
H3C	0.5752	0.5350	0.4715	0.186*
C4	0.6077 (3)	0.7061 (6)	0.5606 (8)	0.0801 (17)
C5	0.6758 (2)	0.6766 (5)	0.5262 (7)	0.0711 (14)
H5A	0.6874	0.6647	0.4118	0.085*
C6	0.7215 (2)	0.6657 (4)	0.6420 (6)	0.0521 (11)
C7	0.7116 (2)	0.6929 (4)	0.8315 (6)	0.0498 (11)
H7A	0.7139	0.6144	0.8911	0.060*
C8	0.6445 (2)	0.7431 (5)	0.8672 (7)	0.0680 (14)
H8A	0.6339	0.7301	0.9874	0.082*
H8B	0.6442	0.8300	0.8458	0.082*
C9	0.5940 (2)	0.6822 (6)	0.7544 (8)	0.0787 (16)
H9A	0.5518	0.7136	0.7837	0.094*
H9B	0.5940	0.5952	0.7760	0.094*
C10	0.7870 (2)	0.6163 (5)	0.5973 (6)	0.0640 (13)
H10A	0.7920	0.6179	0.4731	0.077*
H10B	0.7892	0.5320	0.6338	0.077*
C11	0.8424 (2)	0.6850 (5)	0.6776 (6)	0.0577 (12)
H11A	0.8465	0.7645	0.6245	0.069*
H11B	0.8822	0.6409	0.6592	0.069*
C12	0.82995 (19)	0.6994 (4)	0.8726 (5)	0.0445 (10)
H12A	0.8203	0.6169	0.9128	0.053*
C13	0.7675 (2)	0.7720 (4)	0.9057 (5)	0.0484 (11)
C14	0.8910 (2)	0.7370 (4)	0.9743 (6)	0.0532 (12)
C15	0.8742 (3)	0.7497 (5)	1.1667 (7)	0.0662 (14)
H15A	0.8647	0.6699	1.2137	0.079*
H15B	0.9110	0.7821	1.2280	0.079*
C16	0.8169 (3)	0.8327 (5)	1.1954 (7)	0.0697 (14)
H16A	0.8081	0.8385	1.3178	0.084*
H16B	0.8270	0.9137	1.1535	0.084*
C17	0.7580 (2)	0.7849 (5)	1.1030 (5)	0.0562 (13)
H17A	0.7224	0.8396	1.1244	0.067*
H17B	0.7469	0.7061	1.1505	0.067*
C18	0.7663 (2)	0.8972 (4)	0.8218 (7)	0.0620 (13)
H18A	0.8006	0.9458	0.8672	0.093*
H18B	0.7260	0.9360	0.8456	0.093*
H18C	0.7715	0.8887	0.6995	0.093*
C19	0.9237 (2)	0.8539 (5)	0.9099 (8)	0.0758 (16)
H19A	0.9608	0.8706	0.9794	0.114*
H19B	0.8941	0.9206	0.9181	0.114*
H19C	0.9366	0.8435	0.7922	0.114*
C20	0.9393 (2)	0.6334 (4)	0.9643 (7)	0.062

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0487 (19)	0.069 (2)	0.185 (4)	0.0073 (17)	−0.008 (3)	−0.014 (3)
O2	0.065 (2)	0.063 (2)	0.223 (6)	0.0112 (18)	−0.001 (3)	0.030 (3)
C1	0.150 (8)	0.132 (7)	0.166 (10)	0.000 (6)	−0.001 (8)	0.027 (7)
C2	0.098 (5)	0.129 (7)	0.130 (7)	0.024 (5)	−0.018 (5)	0.027 (6)
C3	0.090 (5)	0.158 (7)	0.124 (6)	−0.019 (5)	−0.015 (5)	−0.021 (6)
C4	0.056 (3)	0.104 (5)	0.080 (4)	0.003 (3)	−0.012 (3)	−0.004 (4)
C5	0.065 (3)	0.086 (4)	0.062 (3)	0.001 (3)	0.007 (3)	−0.009 (3)
C6	0.056 (3)	0.049 (2)	0.051 (3)	0.000 (2)	0.004 (2)	−0.009 (2)
C7	0.050 (3)	0.052 (3)	0.048 (2)	0.007 (2)	0.010 (2)	0.007 (2)
C8	0.049 (3)	0.088 (3)	0.067 (3)	0.012 (3)	0.004 (3)	−0.003 (3)
C9	0.053 (3)	0.084 (4)	0.100 (4)	0.003 (3)	0.004 (3)	0.008 (4)
C10	0.064 (3)	0.076 (3)	0.052 (3)	0.008 (3)	0.008 (2)	−0.013 (3)
C11	0.051 (3)	0.069 (3)	0.053 (3)	0.010 (2)	0.014 (2)	−0.002 (3)
C12	0.049 (2)	0.042 (2)	0.042 (2)	0.0070 (19)	0.007 (2)	0.005 (2)
C13	0.055 (2)	0.050 (2)	0.041 (2)	0.013 (2)	0.004 (2)	0.001 (2)
C14	0.052 (2)	0.045 (2)	0.063 (3)	0.002 (2)	−0.004 (2)	0.006 (2)
C15	0.071 (3)	0.070 (3)	0.057 (3)	0.016 (3)	−0.011 (3)	0.000 (3)
C16	0.089 (4)	0.069 (3)	0.052 (3)	0.017 (3)	−0.009 (3)	−0.008 (3)
C17	0.068 (3)	0.059 (3)	0.042 (3)	0.016 (2)	0.001 (2)	−0.004 (2)
C18	0.073 (3)	0.051 (3)	0.062 (3)	0.010 (2)	−0.006 (3)	0.007 (2)
C19	0.070 (3)	0.065 (3)	0.093 (4)	−0.013 (3)	−0.021 (3)	0.011 (3)
C20	0.068	0.053	0.064	−0.002	−0.007	0.008

Geometric parameters (Å, º) top

O1—C20	1.223 (6)	C10—H10A	0.9700
O2—C20	1.273 (6)	C10—H10B	0.9700
O2—H2B	0.8200	C11—C12	1.544 (6)
C1—C2	1.251 (11)	C11—H11A	0.9700
C1—H1A	0.9300	C11—H11B	0.9700
C1—H1B	0.9300	C12—C13	1.546 (6)
C2—C4	1.531 (10)	C12—C14	1.552 (6)
C2—H2A	0.9300	C12—H12A	0.9800
C3—C4	1.592 (9)	C13—C18	1.523 (6)
C3—H3A	0.9600	C13—C17	1.551 (6)
C3—H3B	0.9600	C14—C20	1.520 (6)
C3—H3C	0.9600	C14—C19	1.538 (6)
C4—C5	1.479 (7)	C14—C15	1.541 (7)
C4—C9	1.554 (8)	C15—C16	1.517 (7)
C5—C6	1.315 (6)	C15—H15A	0.9700
C5—H5A	0.9300	C15—H15B	0.9700
C6—C10	1.507 (6)	C16—C17	1.515 (7)
C6—C7	1.516 (6)	C16—H16A	0.9700
C7—C8	1.527 (6)	C16—H16B	0.9700
C7—C13	1.563 (6)	C17—H17A	0.9700
C7—H7A	0.9800	C17—H17B	0.9700
C8—C9	1.524 (7)	C18—H18A	0.9600
C8—H8A	0.9700	C18—H18B	0.9600
C8—H8B	0.9700	C18—H18C	0.9600
C9—H9A	0.9700	C19—H19A	0.9600
C9—H9B	0.9700	C19—H19B	0.9600
C10—C11	1.514 (7)	C19—H19C	0.9600

C20—O2—H2B	109.5	C12—C11—H11B	109.9
C2—C1—H1A	120.0	H11A—C11—H11B	108.3
C2—C1—H1B	120.0	C11—C12—C13	110.9 (3)
H1A—C1—H1B	120.0	C11—C12—C14	112.8 (4)
C1—C2—C4	131.5 (10)	C13—C12—C14	117.8 (3)
C1—C2—H2A	114.3	C11—C12—H12A	104.6
C4—C2—H2A	114.3	C13—C12—H12A	104.6
C4—C3—H3A	109.5	C14—C12—H12A	104.6
C4—C3—H3B	109.5	C18—C13—C12	114.1 (4)
H3A—C3—H3B	109.5	C18—C13—C17	109.7 (4)
C4—C3—H3C	109.5	C12—C13—C17	108.6 (4)
H3A—C3—H3C	109.5	C18—C13—C7	109.4 (4)
H3B—C3—H3C	109.5	C12—C13—C7	106.2 (3)
C5—C4—C2	109.1 (6)	C17—C13—C7	108.7 (4)
C5—C4—C9	108.3 (5)	C20—C14—C19	108.4 (4)
C2—C4—C9	114.9 (6)	C20—C14—C15	105.6 (4)
C5—C4—C3	107.9 (5)	C19—C14—C15	109.9 (4)
C2—C4—C3	106.9 (6)	C20—C14—C12	108.5 (4)
C9—C4—C3	109.5 (6)	C19—C14—C12	114.8 (4)
C6—C5—C4	126.2 (5)	C15—C14—C12	109.3 (4)
C6—C5—H5A	116.9	C16—C15—C14	112.1 (4)
C4—C5—H5A	116.9	C16—C15—H15A	109.2
C5—C6—C10	122.0 (4)	C14—C15—H15A	109.2
C5—C6—C7	123.1 (4)	C16—C15—H15B	109.2
C10—C6—C7	114.7 (4)	C14—C15—H15B	109.2
C6—C7—C8	111.8 (4)	H15A—C15—H15B	107.9
C6—C7—C13	111.4 (4)	C17—C16—C15	111.0 (4)
C8—C7—C13	114.4 (4)	C17—C16—H16A	109.4
C6—C7—H7A	106.2	C15—C16—H16A	109.4
C8—C7—H7A	106.2	C17—C16—H16B	109.4
C13—C7—H7A	106.2	C15—C16—H16B	109.4
C9—C8—C7	111.6 (4)	H16A—C16—H16B	108.0
C9—C8—H8A	109.3	C16—C17—C13	113.4 (4)
C7—C8—H8A	109.3	C16—C17—H17A	108.9
C9—C8—H8B	109.3	C13—C17—H17A	108.9
C7—C8—H8B	109.3	C16—C17—H17B	108.9
H8A—C8—H8B	108.0	C13—C17—H17B	108.9
C8—C9—C4	110.8 (5)	H17A—C17—H17B	107.7
C8—C9—H9A	109.5	C13—C18—H18A	109.5
C4—C9—H9A	109.5	C13—C18—H18B	109.5
C8—C9—H9B	109.5	H18A—C18—H18B	109.5
C4—C9—H9B	109.5	C13—C18—H18C	109.5
H9A—C9—H9B	108.1	H18A—C18—H18C	109.5
C6—C10—C11	114.5 (4)	H18B—C18—H18C	109.5
C6—C10—H10A	108.6	C14—C19—H19A	109.5
C11—C10—H10A	108.6	C14—C19—H19B	109.5
C6—C10—H10B	108.6	H19A—C19—H19B	109.5
C11—C10—H10B	108.6	C14—C19—H19C	109.5
H10A—C10—H10B	107.6	H19A—C19—H19C	109.5
C10—C11—C12	109.1 (4)	H19B—C19—H19C	109.5
C10—C11—H11A	109.9	O1—C20—O2	120.0 (5)
C12—C11—H11A	109.9	O1—C20—C14	121.1 (4)
C10—C11—H11B	109.9	O2—C20—C14	118.8 (4)

C1—C2—C4—C5	−138.0 (10)	C14—C12—C13—C7	−163.7 (4)
C1—C2—C4—C9	−16.1 (13)	C6—C7—C13—C18	66.0 (5)
C1—C2—C4—C3	105.6 (12)	C8—C7—C13—C18	−62.1 (5)
C2—C4—C5—C6	108.1 (7)	C6—C7—C13—C12	−57.6 (4)
C9—C4—C5—C6	−17.6 (9)	C8—C7—C13—C12	174.3 (4)
C3—C4—C5—C6	−136.1 (6)	C6—C7—C13—C17	−174.2 (4)
C4—C5—C6—C10	170.2 (5)	C8—C7—C13—C17	57.7 (5)
C4—C5—C6—C7	−5.4 (9)	C11—C12—C14—C20	−65.6 (5)
C5—C6—C7—C8	−4.4 (7)	C13—C12—C14—C20	163.0 (4)
C10—C6—C7—C8	179.7 (4)	C11—C12—C14—C19	55.8 (5)
C5—C6—C7—C13	−133.9 (5)	C13—C12—C14—C19	−75.5 (5)
C10—C6—C7—C13	50.2 (5)	C11—C12—C14—C15	179.8 (4)
C6—C7—C8—C9	37.2 (6)	C13—C12—C14—C15	48.4 (5)
C13—C7—C8—C9	165.1 (4)	C20—C14—C15—C16	−168.9 (4)
C7—C8—C9—C4	−61.6 (6)	C19—C14—C15—C16	74.3 (5)
C5—C4—C9—C8	49.7 (7)	C12—C14—C15—C16	−52.4 (6)
C2—C4—C9—C8	−72.5 (6)	C14—C15—C16—C17	59.3 (6)
C3—C4—C9—C8	167.2 (5)	C15—C16—C17—C13	−58.9 (6)
C5—C6—C10—C11	137.5 (5)	C18—C13—C17—C16	−74.5 (5)
C7—C6—C10—C11	−46.6 (6)	C12—C13—C17—C16	50.8 (5)
C6—C10—C11—C12	50.2 (6)	C7—C13—C17—C16	165.9 (4)
C10—C11—C12—C13	−60.7 (5)	C19—C14—C20—O1	18.5 (7)
C10—C11—C12—C14	164.6 (4)	C15—C14—C20—O1	−99.2 (6)
C11—C12—C13—C18	−56.5 (5)	C12—C14—C20—O1	143.8 (5)
C14—C12—C13—C18	75.7 (5)	C19—C14—C20—O2	−160.4 (5)
C11—C12—C13—C17	−179.2 (4)	C15—C14—C20—O2	81.9 (6)
C14—C12—C13—C17	−47.0 (5)	C12—C14—C20—O2	−35.2 (7)
C11—C12—C13—C7	64.1 (4)

Experimental details

Crystal data
Chemical formula	C₂₀H₃₀O₂
M_r	302.44
Crystal system, space group	Orthorhombic, P2₁2₁2
Temperature (K)	293
a, b, c (Å)	20.818 (4), 10.990 (2), 7.7650 (16)
V (Å³)	1776.6 (6)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.07
Crystal size (mm)	0.30 × 0.20 × 0.10

Data collection
Diffractometer	Enraf–Nonius CAD-4 diffractometer
Absorption correction	ψ scan (North et al., 1968)
T_min, T_max	0.979, 0.993
No. of measured, independent and observed [I > 2σ(I)] reflections	1862, 1862, 1231
R_int	0.000
(sin θ/λ)_max (Å⁻¹)	0.600

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.065, 0.188, 1.00
No. of reflections	1862
No. of parameters	193
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.16, −0.17

Computer programs: CAD-4 EXPRESS (Enraf–Nonius, 1994), XCAD4 (Harms & Wocadlo,1995), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008), SHEXL97 (Sheldrick, 2008).

Acknowledgements

This work was supported by the National Natural Science Foundation of China under grant No. 30571466.

References

Enraf–Nonius (1994). CAD-4 Software. Enraf–Nonius, Delft, The Netherlands. Google Scholar
Green, B., Harris, A. & Whalley, W. B. (1958). J. Chem. Soc. pp. 4715–4719. CrossRef Web of Science Google Scholar
Harms, K. & Wocadlo, S. (1995). XCAD4. University of Marburg, Germany. Google Scholar
Harris, G. C. & Sanderson, T. F. (1948). J. Am. Chem. Soc. 70, 2081–2085. CrossRef PubMed CAS Web of Science Google Scholar
Imaizumi, Y., Sakamoto, K., Yamada, A., Hotta, A., Ohya, S., Muraki, K., Uchiyama, M. & Ohwada, T. (2002). Mol. Pharmacol. 62, 836–846. Web of Science CrossRef PubMed CAS Google Scholar
North, A. C. T., Phillips, D. C. & Mathews, F. S. (1968). Acta Cryst. A24, 351–359. CrossRef IUCr Journals Web of Science Google Scholar
Rubio, J., Calderon, J. S., Flores, A., Castroa, C. & Cespedes, C. L. (2005). J. Biosci. 60, 711–716. CAS Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar

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