organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890

2-Amino-4-(2-fluoro­phen­yl)-5,6-di­hydro­benzo[h]quinoline-3-carbo­nitrile

aDepartment of Applied Chemistry, College of Science, Nanjing University of Technology, Nanjing 210009, People's Republic of China, bDepartment of Biotechnology and Pharmaceutical Engineering, Nanjing University of Technology, Nanjing 210009, People's Republic of China, and cCollege of Science, Nanjing University of Technology, Nanjing 210009, People's Republic of China
*Correspondence e-mail: guocheng@njut.edu.cn

(Received 19 November 2010; accepted 3 December 2010; online 11 December 2010)

In the title compound, C20H14FN3, the F atom of the fluoro-substituted benzene ring in the 4-position of the 5,6-dihydro­benzo[h]quinoline system is disordered over two positions (0.80 and 0.20 occupancy). The dihedral angle between the pyridine and fluorobenzene rings is 73.2 (2) Å. The crystal structure is established by inter­molecular N—H⋯N hydrogen bonds, forming a three-dimensional network.

Related literature

For use of the title compound as an inter­mediate, see Shi et al. (2005[Shi, F., Tu, S. J., Fang, F. & Li, T. J. (2005). Arkivoc, pp. 137-142.]). For standard bond lengths, see: Allen et al. (1987[Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1-19.]).

[Scheme 1]

Experimental

Crystal data
  • C20H14FN3

  • Mr = 315.34

  • Orthorhombic, P 21 21 21

  • a = 6.9690 (14) Å

  • b = 12.716 (3) Å

  • c = 17.379 (4) Å

  • V = 1540.1 (5) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.09 mm−1

  • T = 293 K

  • 0.30 × 0.20 × 0.20 mm

Data collection
  • Enraf–Nonius CAD-4 diffractometer

  • Absorption correction: ψ scan (North et al., 1998[North, A. C. T., Phillips, D. C. & Mathews, F. S. (1968). Acta Cryst. A24, 351-359.]) Tmin = 0.973, Tmax = 0.982

  • 1641 measured reflections

  • 1641 independent reflections

  • 1231 reflections with I > 2σ(I)

  • Rint = 0.0315

  • 3 standard reflections every 200 reflections intensity decay: 1%

Refinement
  • R[F2 > 2σ(F2)] = 0.052

  • wR(F2) = 0.161

  • S = 1.02

  • 1641 reflections

  • 226 parameters

  • 12 restraints

  • H-atom parameters constrained

  • Δρmax = 0.19 e Å−3

  • Δρmin = −0.17 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N2—H2A⋯N3i 0.86 2.45 3.215 (5) 150
Symmetry code: (i) [-x+2, y+{\script{1\over 2}}, -z+{\script{3\over 2}}].

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994)[Enraf-Nonius (1994). CAD-4 EXPRESS. Enraf-Nonius, Delft, The Netherlands.]; cell refinement: CAD-4 EXPRESS[Enraf-Nonius (1994). CAD-4 EXPRESS. Enraf-Nonius, Delft, The Netherlands.]; data reduction: XCAD4 (Harms & Wocadlo, 1995[Harms, K. & Wocadlo, S. (1995). XCAD4. University of Marburg, Germany.]); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); software used to prepare material for publication: SHELXTL.

Supporting information


Comment top

The title compound, C20H14F1N3, (I), is an important intermediate in the preparation of heterocyclic compounds (Shi et al., 2005). Thus, it's crystal structure is reported herein.

The fundamental buliding unit of I is composed of one fluorine substituted benzene ring attached to a 5,6-dihydrobenzo[h]quinoline ring in 4-position. In addition, there is an amino group in 2-position and a nitrile function in 3-position (Fig 1). The o-fluoro-phenyl group is disordered over two positions. Bond lengths and angles of the compound are within normal ranges (Allen et al., 1987). The crystal structure of the title compound is established by intermolecular N—H···N hydrogen bonds forming a three dimensional network (Fig 2).

Related literature top

For use of the title compound as an intermediate, see Shi et al. (2005). For standard bond lengths, see: Allen et al. (1987).

Experimental top

The title compound, (I) was prepared under microwave irradiation, an environmentally friendly method. 2 mmol of 2-fluorobenzaldehyde, 2 mmol of malononitrile, 16 mmol of ammonium acetate and 2 mmol of 1,2,3,4-tetrahydronaphthalen-1-one were dissolved in 3 mL absolute ethanol. The reaction mixture was stirred at 90°C additionally irradiating the mixture with microwaves (400 W, 6 h). After cooling down to room temperature pure (I) was obtained directly from the solution. Crystals suitable for X-ray analysis were obtained by dissolving (I) (0.5 g) in methanol (20 ml) and slowly evaporating the solvent at the room temperature for about 7 days.

Refinement top

In the absence of anomalous scattering effects, Friedel pairs were merged. H atoms were positioned geometrically, with C—H = 0.93 Å for aromatic H, 0.97 Å for alkyl H and 0.86 Å for N—H, respectively. They were constrained to ride on their parent atoms, with Uiso(H) = xUeq(C, N), where x = 1.2 for aromatic H, and x = 1.5 for other H.

Structure description top

The title compound, C20H14F1N3, (I), is an important intermediate in the preparation of heterocyclic compounds (Shi et al., 2005). Thus, it's crystal structure is reported herein.

The fundamental buliding unit of I is composed of one fluorine substituted benzene ring attached to a 5,6-dihydrobenzo[h]quinoline ring in 4-position. In addition, there is an amino group in 2-position and a nitrile function in 3-position (Fig 1). The o-fluoro-phenyl group is disordered over two positions. Bond lengths and angles of the compound are within normal ranges (Allen et al., 1987). The crystal structure of the title compound is established by intermolecular N—H···N hydrogen bonds forming a three dimensional network (Fig 2).

For use of the title compound as an intermediate, see Shi et al. (2005). For standard bond lengths, see: Allen et al. (1987).

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: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. Molecular structure of (I), with the atom-numbering scheme and displacement ellipsoids at the 30% probability level.
[Figure 2] Fig. 2. Packing diagram of (I). Hydrogen bonds are shown as dashed lines.
2-Amino-4-(2-fluorophenyl)-5,6-dihydrobenzo[h]quinoline-3-carbonitrile top
Crystal data top
C20H14FN3Dx = 1.360 Mg m3
Mr = 315.34Melting point: 438.15 K
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 25 reflections
a = 6.9690 (14) Åθ = 9–13°
b = 12.716 (3) ŵ = 0.09 mm1
c = 17.379 (4) ÅT = 293 K
V = 1540.1 (5) Å3Block, yellow
Z = 40.30 × 0.20 × 0.20 mm
F(000) = 656
Data collection top
Enraf–Nonius CAD-4
diffractometer
1231 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.032
Graphite monochromatorθmax = 25.3°, θmin = 2.0°
ω/2θ scansh = 08
Absorption correction: ψ scan
(North et al., 1998)
k = 015
Tmin = 0.973, Tmax = 0.982l = 020
1641 measured reflections3 standard reflections every 200 reflections
1641 independent reflections intensity decay: 1%
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.052Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.161H-atom parameters constrained
S = 1.02 w = 1/[σ2(Fo2) + (0.109P)2]
where P = (Fo2 + 2Fc2)/3
1641 reflections(Δ/σ)max < 0.001
226 parametersΔρmax = 0.19 e Å3
12 restraintsΔρmin = 0.17 e Å3
Crystal data top
C20H14FN3V = 1540.1 (5) Å3
Mr = 315.34Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 6.9690 (14) ŵ = 0.09 mm1
b = 12.716 (3) ÅT = 293 K
c = 17.379 (4) Å0.30 × 0.20 × 0.20 mm
Data collection top
Enraf–Nonius CAD-4
diffractometer
1231 reflections with I > 2σ(I)
Absorption correction: ψ scan
(North et al., 1998)
Rint = 0.032
Tmin = 0.973, Tmax = 0.9823 standard reflections every 200 reflections
1641 measured reflections intensity decay: 1%
1641 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.05212 restraints
wR(F2) = 0.161H-atom parameters constrained
S = 1.02Δρmax = 0.19 e Å3
1641 reflectionsΔρmin = 0.17 e Å3
226 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
xyzUiso*/UeqOcc. (<1)
C10.9531 (6)0.0831 (3)0.49848 (19)0.0426 (9)
N10.9958 (5)0.2550 (2)0.55568 (16)0.0401 (8)
N21.0177 (6)0.2774 (2)0.68616 (17)0.0522 (9)
H2A1.03490.34350.67840.063*
H2B1.01660.25300.73230.063*
N30.9601 (7)0.0234 (3)0.77208 (18)0.0676 (12)
C20.9338 (9)0.0206 (3)0.4259 (2)0.0649 (13)
H2C0.80130.02170.40890.078*
H2D0.96950.05190.43560.078*
C31.0620 (9)0.0662 (3)0.3634 (2)0.0734 (16)
H3A1.19550.05610.37730.088*
H3B1.03890.02940.31540.088*
C41.0233 (7)0.1807 (3)0.3527 (2)0.0518 (11)
C51.0325 (8)0.2273 (3)0.2808 (2)0.0642 (13)
H5A1.05950.18620.23780.077*
C61.0010 (7)0.3334 (3)0.2722 (2)0.0590 (11)
H6A1.00470.36360.22350.071*
C70.9642 (7)0.3947 (3)0.3356 (2)0.0557 (11)
H7A0.94400.46660.32990.067*
C80.9571 (6)0.3495 (3)0.4076 (2)0.0449 (9)
H8A0.93240.39140.45030.054*
C90.9862 (6)0.2430 (3)0.41728 (19)0.0407 (9)
C100.9766 (5)0.1922 (3)0.49386 (19)0.0390 (8)
C110.9925 (6)0.2118 (3)0.62584 (19)0.0382 (8)
C120.9689 (6)0.1031 (3)0.63549 (19)0.0382 (8)
C130.9470 (6)0.0380 (3)0.5712 (2)0.0398 (9)
C140.9174 (6)0.0773 (3)0.5810 (2)0.0446 (10)
C150.7404 (8)0.1240 (4)0.5688 (3)0.0615 (12)
H150.63940.07810.55910.074*0.80
C160.7092 (9)0.2297 (4)0.5788 (3)0.0739 (16)
H16A0.58810.25830.57050.089*
C170.8575 (10)0.2917 (4)0.6009 (2)0.0757 (17)
H17A0.83760.36330.60840.091*
C181.0355 (9)0.2501 (3)0.6122 (2)0.0641 (14)
H18A1.13780.29340.62550.077*
C191.0625 (8)0.1438 (3)0.6038 (2)0.0557 (12)
H191.18330.11530.61300.067*0.20
C200.9635 (7)0.0585 (3)0.7116 (2)0.0479 (10)
F10.610 (2)0.0743 (11)0.5394 (10)0.083 (4)0.21
F1'1.2344 (6)0.1074 (3)0.6101 (3)0.0917 (13)0.80
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.053 (2)0.0301 (17)0.0443 (18)0.0026 (18)0.0015 (19)0.0052 (15)
N10.0467 (19)0.0329 (14)0.0408 (15)0.0002 (15)0.0006 (15)0.0022 (13)
N20.077 (3)0.0393 (16)0.0398 (16)0.0077 (19)0.0009 (17)0.0049 (13)
N30.115 (3)0.0460 (18)0.0422 (18)0.006 (2)0.004 (2)0.0062 (15)
C20.115 (4)0.039 (2)0.0409 (19)0.004 (3)0.002 (2)0.0032 (17)
C30.126 (5)0.043 (2)0.052 (2)0.006 (3)0.014 (3)0.003 (2)
C40.076 (3)0.0390 (19)0.0403 (19)0.002 (2)0.004 (2)0.0021 (16)
C50.099 (4)0.052 (2)0.041 (2)0.005 (3)0.008 (3)0.0039 (19)
C60.076 (3)0.052 (2)0.050 (2)0.003 (3)0.001 (2)0.0174 (19)
C70.064 (3)0.043 (2)0.061 (2)0.000 (2)0.003 (2)0.0166 (19)
C80.049 (2)0.0356 (19)0.050 (2)0.0020 (19)0.003 (2)0.0013 (16)
C90.045 (2)0.0386 (18)0.0385 (18)0.0020 (19)0.0000 (17)0.0019 (15)
C100.044 (2)0.0339 (18)0.0386 (17)0.0025 (18)0.0015 (18)0.0023 (15)
C110.042 (2)0.0331 (16)0.0397 (17)0.0027 (17)0.0033 (17)0.0017 (15)
C120.041 (2)0.0346 (17)0.0391 (17)0.0020 (17)0.0015 (18)0.0003 (15)
C130.050 (2)0.0295 (17)0.0399 (17)0.0002 (18)0.0013 (19)0.0017 (14)
C140.066 (3)0.0326 (19)0.0353 (19)0.005 (2)0.0021 (19)0.0018 (16)
C150.076 (3)0.047 (2)0.061 (3)0.007 (2)0.010 (3)0.003 (2)
C160.100 (4)0.052 (3)0.069 (3)0.030 (3)0.013 (3)0.013 (2)
C170.135 (5)0.040 (2)0.052 (3)0.022 (3)0.003 (3)0.011 (2)
C180.102 (4)0.038 (2)0.052 (2)0.017 (3)0.001 (3)0.0077 (19)
C190.079 (3)0.034 (2)0.054 (2)0.004 (2)0.000 (2)0.0033 (18)
C200.067 (3)0.0336 (17)0.043 (2)0.002 (2)0.004 (2)0.0037 (17)
F10.062 (8)0.058 (8)0.130 (12)0.007 (7)0.034 (8)0.002 (8)
F1'0.071 (2)0.056 (2)0.148 (4)0.002 (2)0.024 (2)0.010 (2)
Geometric parameters (Å, º) top
C1—C131.389 (5)C7—C81.378 (5)
C1—C101.399 (5)C7—H7A0.9300
C1—C21.496 (5)C8—C91.380 (5)
N1—C111.338 (4)C8—H8A0.9300
N1—C101.345 (4)C9—C101.481 (4)
N2—C111.351 (4)C11—C121.401 (5)
N2—H2A0.8600C12—C131.398 (5)
N2—H2B0.8600C12—C201.439 (5)
N3—C201.143 (4)C13—C141.490 (5)
C2—C31.522 (7)C14—C191.376 (6)
C2—H2C0.9700C14—C151.385 (6)
C2—H2D0.9700C15—F11.217 (14)
C3—C41.492 (6)C15—C161.373 (6)
C3—H3A0.9700C15—H150.9300
C3—H3B0.9700C16—C171.356 (8)
C4—C51.386 (5)C16—H16A0.9300
C4—C91.397 (5)C17—C181.362 (8)
C5—C61.374 (6)C17—H17A0.9300
C5—H5A0.9300C18—C191.373 (6)
C6—C71.374 (6)C18—H18A0.9300
C6—H6A0.9300C19—F1'1.289 (6)
C13—C1—C10117.7 (3)C4—C9—C10118.9 (3)
C13—C1—C2123.0 (3)N1—C10—C1123.6 (3)
C10—C1—C2119.2 (3)N1—C10—C9117.1 (3)
C11—N1—C10118.9 (3)C1—C10—C9119.3 (3)
C11—N2—H2A120.0N1—C11—N2116.8 (3)
C11—N2—H2B120.0N1—C11—C12121.1 (3)
H2A—N2—H2B120.0N2—C11—C12122.1 (3)
C1—C2—C3110.3 (4)C13—C12—C11120.1 (3)
C1—C2—H2C109.6C13—C12—C20119.8 (3)
C3—C2—H2C109.6C11—C12—C20120.1 (3)
C1—C2—H2D109.6C1—C13—C12118.6 (3)
C3—C2—H2D109.6C1—C13—C14120.9 (3)
H2C—C2—H2D108.1C12—C13—C14120.5 (3)
C4—C3—C2110.7 (4)C19—C14—C15115.8 (4)
C4—C3—H3A109.5C19—C14—C13122.4 (4)
C2—C3—H3A109.5C15—C14—C13121.8 (4)
C4—C3—H3B109.5F1—C15—C16116.3 (8)
C2—C3—H3B109.5F1—C15—C14120.3 (8)
H3A—C3—H3B108.1C16—C15—C14122.8 (5)
C5—C4—C9119.4 (3)C16—C15—H15121.2
C5—C4—C3121.4 (3)C14—C15—H15115.6
C9—C4—C3119.1 (3)C17—C16—C15119.0 (6)
C6—C5—C4120.6 (4)C17—C16—H16A120.5
C6—C5—H5A119.8C15—C16—H16A120.5
C4—C5—H5A119.5C16—C17—C18120.6 (4)
C5—C6—C7120.1 (3)C16—C17—H17A119.7
C5—C6—H6A120.0C18—C17—H17A119.7
C7—C6—H6A120.0C17—C18—C19119.4 (5)
C6—C7—C8119.8 (3)C17—C18—H18A120.3
C6—C7—H7A120.1C19—C18—H18A120.3
C8—C7—H7A120.1F1'—C19—C18118.1 (5)
C7—C8—C9121.0 (3)F1'—C19—C14119.2 (4)
C7—C8—H8A119.5C18—C19—C14122.3 (5)
C9—C8—H8A119.5C18—C19—H19119.3
C8—C9—C4119.1 (3)C14—C19—H19118.3
C8—C9—C10122.1 (3)N3—C20—C12179.6 (5)
C13—C1—C2—C3144.0 (4)N2—C11—C12—C13178.8 (4)
C10—C1—C2—C336.6 (6)N1—C11—C12—C20179.3 (4)
C1—C2—C3—C453.6 (6)N2—C11—C12—C202.5 (7)
C2—C3—C4—C5144.6 (5)C10—C1—C13—C121.5 (6)
C2—C3—C4—C938.6 (7)C2—C1—C13—C12179.2 (4)
C9—C4—C5—C61.5 (8)C10—C1—C13—C14178.5 (4)
C3—C4—C5—C6178.4 (5)C2—C1—C13—C140.9 (6)
C4—C5—C6—C71.4 (8)C11—C12—C13—C11.3 (6)
C5—C6—C7—C80.6 (8)C20—C12—C13—C1179.9 (4)
C6—C7—C8—C90.1 (7)C11—C12—C13—C14178.6 (4)
C7—C8—C9—C40.0 (7)C20—C12—C13—C140.2 (6)
C7—C8—C9—C10179.1 (4)C1—C13—C14—C19107.6 (5)
C5—C4—C9—C80.8 (7)C12—C13—C14—C1972.5 (5)
C3—C4—C9—C8177.7 (5)C1—C13—C14—C1573.7 (5)
C5—C4—C9—C10180.0 (4)C12—C13—C14—C15106.3 (5)
C3—C4—C9—C103.1 (7)C19—C14—C15—F1170.7 (10)
C11—N1—C10—C10.0 (6)C13—C14—C15—F110.5 (12)
C11—N1—C10—C9178.4 (3)C19—C14—C15—C160.0 (7)
C13—C1—C10—N10.9 (6)C13—C14—C15—C16178.8 (4)
C2—C1—C10—N1179.8 (4)F1—C15—C16—C17170.6 (10)
C13—C1—C10—C9179.3 (3)C14—C15—C16—C170.5 (8)
C2—C1—C10—C91.4 (6)C15—C16—C17—C180.8 (8)
C8—C9—C10—N119.4 (6)C16—C17—C18—C192.4 (8)
C4—C9—C10—N1161.5 (4)C17—C18—C19—F1'175.7 (4)
C8—C9—C10—C1162.1 (4)C17—C18—C19—C142.9 (7)
C4—C9—C10—C117.0 (6)C15—C14—C19—F1'174.4 (4)
C10—N1—C11—N2178.2 (3)C13—C14—C19—F1'6.8 (6)
C10—N1—C11—C120.2 (6)C15—C14—C19—C181.7 (6)
N1—C11—C12—C130.5 (6)C13—C14—C19—C18179.5 (4)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2A···N3i0.862.453.215 (5)150
Symmetry code: (i) x+2, y+1/2, z+3/2.

Experimental details

Crystal data
Chemical formulaC20H14FN3
Mr315.34
Crystal system, space groupOrthorhombic, P212121
Temperature (K)293
a, b, c (Å)6.9690 (14), 12.716 (3), 17.379 (4)
V3)1540.1 (5)
Z4
Radiation typeMo Kα
µ (mm1)0.09
Crystal size (mm)0.30 × 0.20 × 0.20
Data collection
DiffractometerEnraf–Nonius CAD-4
Absorption correctionψ scan
(North et al., 1998)
Tmin, Tmax0.973, 0.982
No. of measured, independent and
observed [I > 2σ(I)] reflections
1641, 1641, 1231
Rint0.032
(sin θ/λ)max1)0.601
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.052, 0.161, 1.02
No. of reflections1641
No. of parameters226
No. of restraints12
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.19, 0.17

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

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2A···N3i0.862.453.215 (5)150
Symmetry code: (i) x+2, y+1/2, z+3/2.
 

Acknowledgements

We gratefully acknowledge the Analysis Center of Nanjing University.

References

First citationAllen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1–19.  CSD CrossRef Web of Science Google Scholar
First citationEnraf–Nonius (1994). CAD-4 EXPRESS. Enraf–Nonius, Delft, The Netherlands.  Google Scholar
First citationHarms, K. & Wocadlo, S. (1995). XCAD4. University of Marburg, Germany.  Google Scholar
First citationNorth, A. C. T., Phillips, D. C. & Mathews, F. S. (1968). Acta Cryst. A24, 351–359.  CrossRef IUCr Journals Web of Science Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationShi, F., Tu, S. J., Fang, F. & Li, T. J. (2005). Arkivoc, pp. 137–142.  CrossRef Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds