9,9-Dibutyl-9H-fluorene-2-carbonitrile

Zhao, D.; Jiang, P.; Zhu, H.-J.

doi:10.1107/S1600536812022672

organic compounds

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ISSN: 2056-9890

Volume 68| Part 6| June 2012| Page o1903

doi:10.1107/S1600536812022672

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9,9-Dibutyl-9H-fluorene-2-carbonitrile

Dong-dong Zhao,^a Peng Jiang ^b and Hong-Jun Zhu ^c ^*

^aDepartment of Chemical Engineering, College of Science, Nanjing University of Technology, Nanjing 210009, People's Republic of China, ^bDepartment of Organic Chemistry, College of Science, Nanjing University of Technology, Nanjing 210009, People's Republic of China, and ^cDepartment of Applied Chemistry, College of Science, Nanjing University of Technology, Nanjing 210009, People's Republic of China
^*Correspondence e-mail: zhuhj@njut.edu.cn

(Received 30 April 2012; accepted 18 May 2012; online 26 May 2012)

The fluorene fragment of the title compound, C₂₂H₂₅N, is essentially planar, with an r.m.s deviation of the five-membered ring of 0.005 (2) Å. The dihedral angle between this ring and the outer benzene rings are 1.5 (2) and 0.7 (2)° while that between the benzene rings is 2.1 (2)°. The cyano group makes an angle of 0.3 (2)° with the attached benzene ring.

Related literature

For applications of the title compound, including as a substrate in the synthesis of organic light-emitting materials, see: Jiang et al. (2012 ). For its synthesis, see: Omer et al. (2010 ). For bond-length data, see: Allen et al. (1987 ).

Experimental

Crystal data

C₂₂H₂₅N
M_r = 303.43
Triclinic, $[P \overline 1]$
a = 9.2810 (19) Å
b = 9.994 (2) Å
c = 11.885 (2) Å
α = 100.35 (3)°
β = 96.73 (3)°
γ = 117.42 (3)°
V = 937.0 (3) Å³
Z = 2
Mo Kα radiation
μ = 0.06 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 = 0.982, T_max = 0.994
3652 measured reflections
3420 independent reflections
1875 reflections with I > 2σ(I)
R_int = 0.027
3 standard reflections every 200 reflections intensity decay: 1%

Refinement

R[F² > 2σ(F²)] = 0.068
wR(F²) = 0.186
S = 1.00
3420 reflections
208 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.45 e Å⁻³
Δρ_min = −0.13 e Å⁻³

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994 ); cell refinement: SET4 in 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: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536812022672/im2373sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812022672/im2373Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536812022672/im2373Isup3.cml

checkCIF report

Comment top

The title compound, 2-cyano-9,9-dibutylfluorene, is an important compound which can be used in many fields such as a substrate in the synthesis of organic light-emitting materials (Jiang et al., 2012). We report here the crystal structure of the title compound, (I).

The molecular structure of (I) is shown in Fig. 1. Bond lengths are within normal ranges (Allen et al., 1987).

In the molecule of the title compound, the fluorene fragment of the title compound, C₂₂H₂₅N, is essentially planar with a r.m.s deviation of ring A (C1/C6/C7/C12/C13) of 0.005 (2). The dihedral angle between ring A (C1/C6/C7/C12/C13) and the benzene rings B (C1—C6) and C (C7—C12) is 1.5 (2)° and 0.7 (2)°, respectively. The dihedral angle between the benzene rings B and C is 2.1 (2)°. The angle of cyano group with the benzene ring B is 0.3 (2)°.

Related literature top

For applications of the title compound, including as a substrate in the synthesis of organic light-emitting materials, see: Jiang et al. (2012). For its synthesis, see: Omer et al. (2010). For bond-length data, see: Allen et al. (1987).

Experimental top

The title compound,(I) was prepared according to the literature method (Omer et al., 2010). Yellow block-shaped crystals were obtained by dissolving (I) (0.5 g, 1.04 mmol) in a mixed solution (10 ml petroleum ether and 1 ml EtOAc) and evaporating the solvent slowly at room temperature for about 5 d.

Computing details top

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: SET4 in 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: SHELXTL (Sheldrick, 2008).

Figures top

Fig. 1. The molecular structure of (I) with displacement ellipsoids drawn at the 30% probability level.

9,9-Dibutyl-9H-fluorene-2-carbonitrile top

Crystal data top

C₂₂H₂₅N	Z = 2
M_r = 303.43	F(000) = 328
Triclinic, P1	D_x = 1.075 Mg m⁻³
Hall symbol: -P 1	Melting point: 374 K
a = 9.2810 (19) Å	Mo Kα radiation, λ = 0.71073 Å
b = 9.994 (2) Å	Cell parameters from 25 reflections
c = 11.885 (2) Å	θ = 9–13°
α = 100.35 (3)°	µ = 0.06 mm⁻¹
β = 96.73 (3)°	T = 293 K
γ = 117.42 (3)°	Block, yellow
V = 937.0 (3) Å³	0.30 × 0.20 × 0.10 mm

Data collection top

Enraf–Nonius CAD-4 diffractometer	1875 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.027
Graphite monochromator	θ_max = 25.4°, θ_min = 1.8°
ω/2θ scans	h = 0→11
Absorption correction: ψ scan (North et al., 1968)	k = −12→10
T_min = 0.982, T_max = 0.994	l = −14→14
3652 measured reflections	3 standard reflections every 200 reflections
3420 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)] = 0.068	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.186	H-atom parameters constrained
S = 1.00	w = 1/[σ²(F_o²) + (0.070P)² + 0.3P] where P = (F_o² + 2F_c²)/3
3420 reflections	(Δ/σ)_max < 0.001
208 parameters	Δρ_max = 0.45 e Å⁻³
1 restraint	Δρ_min = −0.13 e Å⁻³

Crystal data top

C₂₂H₂₅N	γ = 117.42 (3)°
M_r = 303.43	V = 937.0 (3) Å³
Triclinic, P1	Z = 2
a = 9.2810 (19) Å	Mo Kα radiation
b = 9.994 (2) Å	µ = 0.06 mm⁻¹
c = 11.885 (2) Å	T = 293 K
α = 100.35 (3)°	0.30 × 0.20 × 0.10 mm
β = 96.73 (3)°

Data collection top

Enraf–Nonius CAD-4 diffractometer	1875 reflections with I > 2σ(I)
Absorption correction: ψ scan (North et al., 1968)	R_int = 0.027
T_min = 0.982, T_max = 0.994	3 standard reflections every 200 reflections
3652 measured reflections	intensity decay: 1%
3420 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.068	1 restraint
wR(F²) = 0.186	H-atom parameters constrained
S = 1.00	Δρ_max = 0.45 e Å⁻³
3420 reflections	Δρ_min = −0.13 e Å⁻³
208 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
N	−0.2377 (4)	−0.2430 (4)	0.3798 (3)	0.1162 (11)
C1	0.2296 (3)	0.0884 (3)	0.2410 (2)	0.0587 (7)
C2	0.1181 (3)	0.0220 (3)	0.3086 (2)	0.0643 (7)
H2A	0.1403	0.0698	0.3881	0.077*
C3	−0.0281 (3)	−0.1178 (3)	0.2548 (3)	0.0692 (7)
C4	−0.0608 (4)	−0.1901 (3)	0.1362 (3)	0.0816 (9)
H4A	−0.1594	−0.2834	0.1014	0.098*
C5	0.0513 (4)	−0.1248 (3)	0.0704 (3)	0.0782 (9)
H5A	0.0301	−0.1742	−0.0086	0.094*
C6	0.1966 (3)	0.0153 (3)	0.1223 (2)	0.0624 (7)
C7	0.3335 (3)	0.1124 (3)	0.0740 (2)	0.0658 (7)
C8	0.3608 (4)	0.0907 (4)	−0.0388 (3)	0.0875 (9)
H8A	0.2854	0.0015	−0.0980	0.105*
C9	0.5023 (5)	0.2045 (5)	−0.0604 (3)	0.1045 (12)
H9A	0.5215	0.1928	−0.1357	0.125*
C10	0.6160 (5)	0.3356 (4)	0.0274 (3)	0.1079 (12)
H10A	0.7116	0.4102	0.0110	0.130*
C11	0.5895 (4)	0.3572 (4)	0.1397 (3)	0.0883 (10)
H11A	0.6659	0.4461	0.1988	0.106*
C12	0.4472 (3)	0.2443 (3)	0.1626 (2)	0.0652 (7)
C13	0.3936 (3)	0.2420 (3)	0.2785 (2)	0.0587 (7)
C14	0.5202 (3)	0.2379 (3)	0.3724 (2)	0.0684 (8)
H14A	0.6249	0.3348	0.3892	0.082*
H14B	0.4798	0.2341	0.4441	0.082*
C15	0.5545 (4)	0.1028 (4)	0.3405 (3)	0.0891 (10)
H15A	0.5793	0.0965	0.2633	0.107*
H15B	0.4544	0.0062	0.3359	0.107*
C16	0.6984 (5)	0.1167 (5)	0.4276 (3)	0.1128 (13)
H16A	0.6845	0.1435	0.5066	0.135*
H16B	0.6929	0.0156	0.4143	0.135*
C17	0.8637 (6)	0.2332 (7)	0.4198 (5)	0.166 (2)
H17A	0.9473	0.2382	0.4789	0.248*
H17B	0.8703	0.3337	0.4319	0.248*
H17C	0.8819	0.2042	0.3435	0.248*
C18	0.3682 (3)	0.3808 (3)	0.3257 (2)	0.0625 (7)
H18A	0.3309	0.3698	0.3981	0.075*
H18B	0.4755	0.4756	0.3451	0.075*
C19	0.2465 (4)	0.4010 (3)	0.2449 (2)	0.0739 (8)
H19A	0.1378	0.3081	0.2269	0.089*
H19B	0.2819	0.4109	0.1718	0.089*
C20	0.2307 (5)	0.5418 (4)	0.2962 (3)	0.1006 (11)
H20A	0.2037	0.5355	0.3722	0.121*
H20B	0.3378	0.6351	0.3089	0.121*
C21	0.1008 (6)	0.5581 (6)	0.2209 (4)	0.1452 (17)
H21A	0.0981	0.6498	0.2590	0.218*
H21B	−0.0064	0.4676	0.2095	0.218*
H21C	0.1279	0.5672	0.1461	0.218*
C22	−0.1465 (4)	−0.1884 (4)	0.3242 (3)	0.0849 (9)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N	0.092 (2)	0.094 (2)	0.125 (3)	0.0158 (18)	0.039 (2)	0.0225 (19)
C1	0.0596 (16)	0.0563 (15)	0.0570 (15)	0.0306 (13)	0.0061 (13)	0.0067 (12)
C2	0.0649 (17)	0.0584 (16)	0.0611 (16)	0.0283 (15)	0.0085 (14)	0.0062 (13)
C3	0.0641 (17)	0.0559 (16)	0.079 (2)	0.0258 (14)	0.0094 (14)	0.0128 (14)
C4	0.074 (2)	0.0562 (17)	0.087 (2)	0.0209 (16)	−0.0050 (18)	0.0046 (16)
C5	0.087 (2)	0.0663 (18)	0.0619 (17)	0.0320 (17)	0.0012 (16)	0.0007 (14)
C6	0.0681 (17)	0.0559 (15)	0.0562 (16)	0.0317 (14)	0.0023 (13)	0.0031 (13)
C7	0.0797 (19)	0.0696 (18)	0.0539 (16)	0.0437 (16)	0.0139 (14)	0.0105 (14)
C8	0.107 (3)	0.083 (2)	0.0657 (19)	0.046 (2)	0.0185 (18)	0.0053 (16)
C9	0.134 (3)	0.107 (3)	0.076 (2)	0.058 (3)	0.047 (2)	0.022 (2)
C10	0.118 (3)	0.100 (3)	0.097 (3)	0.042 (2)	0.053 (2)	0.021 (2)
C11	0.084 (2)	0.084 (2)	0.080 (2)	0.0303 (19)	0.0287 (18)	0.0086 (17)
C12	0.0658 (17)	0.0667 (17)	0.0613 (16)	0.0340 (15)	0.0142 (14)	0.0091 (14)
C13	0.0553 (15)	0.0584 (15)	0.0524 (14)	0.0254 (13)	0.0067 (12)	0.0032 (12)
C14	0.0605 (16)	0.0752 (18)	0.0640 (17)	0.0334 (15)	0.0085 (13)	0.0092 (14)
C15	0.093 (2)	0.094 (2)	0.093 (2)	0.060 (2)	0.0151 (19)	0.0181 (18)
C16	0.121 (3)	0.146 (4)	0.112 (3)	0.097 (3)	0.022 (2)	0.039 (3)
C17	0.101 (3)	0.239 (6)	0.176 (5)	0.105 (4)	0.022 (3)	0.048 (4)
C18	0.0583 (16)	0.0606 (16)	0.0571 (15)	0.0246 (13)	0.0107 (13)	0.0043 (12)
C19	0.0756 (19)	0.0799 (19)	0.0663 (17)	0.0441 (17)	0.0084 (15)	0.0081 (15)
C20	0.116 (3)	0.099 (3)	0.104 (3)	0.073 (2)	0.017 (2)	0.014 (2)
C21	0.178 (4)	0.184 (5)	0.137 (4)	0.143 (4)	0.024 (3)	0.043 (3)
C22	0.074 (2)	0.064 (2)	0.095 (2)	0.0224 (17)	0.0118 (18)	0.0086 (17)

Geometric parameters (Å, º) top

N—C22	1.135 (4)	C13—C14	1.544 (3)
C1—C2	1.382 (3)	C14—C15	1.519 (4)
C1—C6	1.393 (3)	C14—H14A	0.9700
C1—C13	1.522 (3)	C14—H14B	0.9700
C2—C3	1.390 (4)	C15—C16	1.525 (4)
C2—H2A	0.9300	C15—H15A	0.9700
C3—C4	1.390 (4)	C15—H15B	0.9700
C3—C22	1.447 (4)	C16—C17	1.464 (5)
C4—C5	1.366 (4)	C16—H16A	0.9700
C4—H4A	0.9300	C16—H16B	0.9700
C5—C6	1.384 (4)	C17—H17A	0.9600
C5—H5A	0.9300	C17—H17B	0.9600
C6—C7	1.457 (4)	C17—H17C	0.9600
C7—C12	1.385 (4)	C18—C19	1.505 (4)
C7—C8	1.391 (4)	C18—H18A	0.9700
C8—C9	1.376 (4)	C18—H18B	0.9700
C8—H8A	0.9300	C19—C20	1.508 (4)
C9—C10	1.376 (5)	C19—H19A	0.9700
C9—H9A	0.9300	C19—H19B	0.9700
C10—C11	1.383 (4)	C20—C21	1.504 (5)
C10—H10A	0.9300	C20—H20A	0.9700
C11—C12	1.383 (4)	C20—H20B	0.9700
C11—H11A	0.9300	C21—H21A	0.9600
C12—C13	1.519 (3)	C21—H21B	0.9600
C13—C18	1.531 (3)	C21—H21C	0.9600

C2—C1—C6	120.5 (2)	C13—C14—H14B	108.3
C2—C1—C13	128.1 (2)	H14A—C14—H14B	107.4
C6—C1—C13	111.4 (2)	C14—C15—C16	113.8 (3)
C1—C2—C3	118.4 (2)	C14—C15—H15A	108.8
C1—C2—H2A	120.8	C16—C15—H15A	108.8
C3—C2—H2A	120.8	C14—C15—H15B	108.8
C2—C3—C4	120.9 (3)	C16—C15—H15B	108.8
C2—C3—C22	119.0 (3)	H15A—C15—H15B	107.7
C4—C3—C22	120.1 (3)	C17—C16—C15	114.2 (3)
C5—C4—C3	120.3 (3)	C17—C16—H16A	108.7
C5—C4—H4A	119.8	C15—C16—H16A	108.7
C3—C4—H4A	119.8	C17—C16—H16B	108.7
C4—C5—C6	119.5 (3)	C15—C16—H16B	108.7
C4—C5—H5A	120.3	H16A—C16—H16B	107.6
C6—C5—H5A	120.3	C16—C17—H17A	109.5
C5—C6—C1	120.3 (3)	C16—C17—H17B	109.5
C5—C6—C7	131.4 (3)	H17A—C17—H17B	109.5
C1—C6—C7	108.3 (2)	C16—C17—H17C	109.5
C12—C7—C8	120.8 (3)	H17A—C17—H17C	109.5
C12—C7—C6	108.5 (2)	H17B—C17—H17C	109.5
C8—C7—C6	130.7 (3)	C19—C18—C13	116.2 (2)
C9—C8—C7	118.3 (3)	C19—C18—H18A	108.2
C9—C8—H8A	120.9	C13—C18—H18A	108.2
C7—C8—H8A	120.9	C19—C18—H18B	108.2
C8—C9—C10	121.2 (3)	C13—C18—H18B	108.2
C8—C9—H9A	119.4	H18A—C18—H18B	107.4
C10—C9—H9A	119.4	C18—C19—C20	113.2 (2)
C9—C10—C11	120.6 (3)	C18—C19—H19A	108.9
C9—C10—H10A	119.7	C20—C19—H19A	108.9
C11—C10—H10A	119.7	C18—C19—H19B	108.9
C12—C11—C10	118.8 (3)	C20—C19—H19B	108.9
C12—C11—H11A	120.6	H19A—C19—H19B	107.7
C10—C11—H11A	120.6	C21—C20—C19	114.2 (3)
C11—C12—C7	120.3 (3)	C21—C20—H20A	108.7
C11—C12—C13	128.0 (2)	C19—C20—H20A	108.7
C7—C12—C13	111.7 (2)	C21—C20—H20B	108.7
C12—C13—C1	100.2 (2)	C19—C20—H20B	108.7
C12—C13—C18	112.8 (2)	H20A—C20—H20B	107.6
C1—C13—C18	111.7 (2)	C20—C21—H21A	109.5
C12—C13—C14	111.2 (2)	C20—C21—H21B	109.5
C1—C13—C14	111.3 (2)	H21A—C21—H21B	109.5
C18—C13—C14	109.4 (2)	C20—C21—H21C	109.5
C15—C14—C13	115.9 (2)	H21A—C21—H21C	109.5
C15—C14—H14A	108.3	H21B—C21—H21C	109.5
C13—C14—H14A	108.3	N—C22—C3	179.1 (4)
C15—C14—H14B	108.3

C6—C1—C2—C3	−0.8 (4)	C8—C7—C12—C13	−179.0 (3)
C13—C1—C2—C3	177.7 (3)	C6—C7—C12—C13	1.0 (3)
C1—C2—C3—C4	0.6 (4)	C11—C12—C13—C1	179.9 (3)
C1—C2—C3—C22	−179.7 (3)	C7—C12—C13—C1	−0.8 (3)
C2—C3—C4—C5	0.3 (4)	C11—C12—C13—C18	61.0 (4)
C22—C3—C4—C5	−179.4 (3)	C7—C12—C13—C18	−119.7 (2)
C3—C4—C5—C6	−1.0 (4)	C11—C12—C13—C14	−62.3 (4)
C4—C5—C6—C1	0.8 (4)	C7—C12—C13—C14	117.0 (3)
C4—C5—C6—C7	−178.0 (3)	C2—C1—C13—C12	−178.5 (3)
C2—C1—C6—C5	0.1 (4)	C6—C1—C13—C12	0.2 (3)
C13—C1—C6—C5	−178.7 (2)	C2—C1—C13—C18	−58.7 (3)
C2—C1—C6—C7	179.2 (2)	C6—C1—C13—C18	119.9 (2)
C13—C1—C6—C7	0.4 (3)	C2—C1—C13—C14	63.9 (3)
C5—C6—C7—C12	178.1 (3)	C6—C1—C13—C14	−117.5 (2)
C1—C6—C7—C12	−0.9 (3)	C12—C13—C14—C15	−56.8 (3)
C5—C6—C7—C8	−1.9 (5)	C1—C13—C14—C15	54.0 (3)
C1—C6—C7—C8	179.1 (3)	C18—C13—C14—C15	177.9 (2)
C12—C7—C8—C9	−0.9 (5)	C13—C14—C15—C16	171.4 (3)
C6—C7—C8—C9	179.1 (3)	C14—C15—C16—C17	−74.2 (4)
C7—C8—C9—C10	1.2 (5)	C12—C13—C18—C19	56.3 (3)
C8—C9—C10—C11	−1.0 (6)	C1—C13—C18—C19	−55.7 (3)
C9—C10—C11—C12	0.5 (6)	C14—C13—C18—C19	−179.5 (2)
C10—C11—C12—C7	−0.2 (5)	C13—C18—C19—C20	−178.8 (3)
C10—C11—C12—C13	179.1 (3)	C18—C19—C20—C21	−175.8 (3)
C8—C7—C12—C11	0.4 (4)	C2—C3—C22—N	−32 (24)
C6—C7—C12—C11	−179.6 (3)	C4—C3—C22—N	147 (24)

Experimental details

Crystal data
Chemical formula	C₂₂H₂₅N
M_r	303.43
Crystal system, space group	Triclinic, P1
Temperature (K)	293
a, b, c (Å)	9.2810 (19), 9.994 (2), 11.885 (2)
α, β, γ (°)	100.35 (3), 96.73 (3), 117.42 (3)
V (Å³)	937.0 (3)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.06
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	0.982, 0.994
No. of measured, independent and observed [I > 2σ(I)] reflections	3652, 3420, 1875
R_int	0.027
(sin θ/λ)_max (Å⁻¹)	0.603

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.068, 0.186, 1.00
No. of reflections	3420
No. of parameters	208
No. of restraints	1
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.45, −0.13

Computer programs: , SET4 in CAD-4 EXPRESS (Enraf–Nonius, 1994), XCAD4 (Harms & Wocadlo, 1995), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Acknowledgements

The authors thank the Center of Testing and Analysis, Nanjing University, for support.

References

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