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

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ISSN: 2056-9890

6,7-Di­fluoro-1,2,3,4-tetra­hydro­quin­oxa­line-5,8-dicarbo­nitrile

aKey Laboratory of Fine Petrochemical Technology, Changzhou University, Changzhou 213164, People's Republic of China, and bTianjin Entry-Exit Inspection and Quarantine Bureau, Tianjin 300457, People's Republic of China
*Correspondence e-mail: hemingyangjpu@yahoo.com

(Received 29 October 2012; accepted 31 January 2013; online 13 February 2013)

In the title compound, C10H6F2N4, the Car—N bonds are slightly shortened with respect to a standard aniline C—N bond [1.3580 (16) and 1.3618 (16) versus 1.39 Å], thus indicating some ππ conjgation with the electron-acceptor CN groups. The mol­ecule, except for two C atom of the ethyl­ene bridge, is nearly planar, the largest deviation of the other non-H atoms from the mean plane being 0.309 (2) Å. The N—C—C—N torsion angle involving the ethyl­ene bridge is 50.23 (18)°. In the crystal, mol­ecules are connected by pairs of N—H⋯N hydrogen bonds into chains along [21-1].

Related literature

For general background to the synthesis and use of tetra­fluoro­terephthalonitrile and its derivatives, see: Meazza et al. (2007[Meazza, G., Bettarini, F. & Fornara, L. (2007). WO Patent No. 2007101587.]). For reference structural data on tetra­fluoro­terephthalic acid, see: Orthaber et al. (2010[Orthaber, A., Seidel, C., Belaj, F., Albering, J. H., Pietschnig, R. & Ruschewitz, U. (2010). Inorg. Chem. 49, 9350-9357.]). 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.]). For hydrogen bonding graph-set descriptors, see: Etter (1990[Etter, M. C. (1990). Acc. Chem. Res. 23, 120-126.]).

[Scheme 1]

Experimental

Crystal data
  • C10H6F2N4

  • Mr = 220.19

  • Triclinic, [P \overline 1]

  • a = 5.2173 (9) Å

  • b = 8.7011 (15) Å

  • c = 11.1453 (19) Å

  • α = 75.545 (2)°

  • β = 81.854 (2)°

  • γ = 76.427 (2)°

  • V = 474.40 (14) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 0.13 mm−1

  • T = 293 K

  • 0.28 × 0.24 × 0.16 mm

Data collection
  • Bruker APEXII CCD diffractometer

  • Absorption correction: multi-scan (SADABS; Sheldrick, 2003[Sheldrick, G. M. (2003). SADABS. University of Göttingen, Germany.]) Tmin = 0.964, Tmax = 0.980

  • 4155 measured reflections

  • 2141 independent reflections

  • 1816 reflections with I > 2σ(I)

  • Rint = 0.026

Refinement
  • R[F2 > 2σ(F2)] = 0.043

  • wR(F2) = 0.140

  • S = 1.06

  • 2141 reflections

  • 145 parameters

  • H-atom parameters constrained

  • Δρmax = 0.29 e Å−3

  • Δρmin = −0.23 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N3—H3⋯N1i 0.86 2.29 3.075 (2) 152
N4—H4⋯N2ii 0.86 2.21 3.0358 (19) 160
Symmetry codes: (i) -x+1, -y+1, -z+1; (ii) -x-1, -y, -z+2.

Data collection: APEX2 (Bruker, 2007[Bruker (2007). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2007[Bruker (2007). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL and DIAMOND (Brandenburg, 2005[Brandenburg, K. (2005). DIAMOND. Crystal Impact GbR, Bonn, Germany.]); software used to prepare material for publication: SHELXTL.

Supporting information


Comment top

As important organic intermediates, tetrafluoroterephthalonitrile and its hydrolyzed product tetrafluoroterephthalic acid can be used to prepare pesticide tefluthrin (Meazza et al., 2007; Orthaber et al., 2010). The SNAr reaction of tetrafluoroterephthalonitrile with ethylenediamine under ultrasound irradiation yields 6,7-difluoro-1,2,3,4-tetrahydroquinoxaline-5,8-dicarbonitrile [C10H6F2N4, compound (I)] as the main product. While the crystal structure of compound (I) was suspiciously unknown. Herein, we report the crystal structure of (I) for comparison and reference purposes.

Compound (I) crystallizes in triclinic P1 space group. A perspective view of the title compound (I) is shown in Fig. 1. The bond lengths and angles are within normal ranges. In the molecule, two nitrile groups are nearly coplanar with the central benzene plane. Within the tetrahydroquinoxaline ring, the torsion angle N3–C10–C9–N4 is -50.23 (18)°. Hydrogen-bonding interactions between the imino groups and cyano groups give rise to cyclic system of two N–H···N bonds between two adjacent molecules with the graph-set motif R22(12) (Etter, 1990). Due to the chemical symmetry of the molecule itself, such hydrogen-bonding interactions link the molecules to form a one-dimensional (1-D) tape structure (Fig. 2).

Related literature top

For general background to the synthesis and use of tetrafluoroterephthalonitrile and its derivatives, see: Meazza et al. (2007). For reference structural data on tetrafluoroterephthalic acid, see: Orthaber et al. (2010). For standard bond lengths, see: Allen et al. (1987). For hydrogen bonding graph-set descriptors, see: Etter (1990).

Experimental top

Compound (I) was synthesized by the ultrasound reaction of tetrafluoroterephthalonitrile and ethylenediamine at room temperature in the presence of sulfur and assisted by ultrasound irradiation. The title compound was purified through column chromatography with ethyl acetate/petroleum ether as the eluent. Qualified crystalline samples were obtained through slow evaporation from the EtOH solution of (I).

Refinement top

All H atoms were positioned geometrically (C–H = 0.97 Å, N–H = 0.86 Å) and included in the refinement in the riding-model approximation, with Uiso(H) = 1.2Ueq(C,N).

Computing details top

Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and DIAMOND (Brandenburg, 2005); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound showing the atom labelling scheme. Thermal ellipsoids are drawn at the 30% probability level.
[Figure 2] Fig. 2. 1-D hydrogen-bonding tape of (I) formed by N–H···N interactions. Hydrogen bonds indicated by dashed lines.
6,7-Difluoro-1,2,3,4-tetrahydroquinoxaline-5,8-dicarbonitrile top
Crystal data top
C10H6F2N4Z = 2
Mr = 220.19F(000) = 224
Triclinic, P1Dx = 1.541 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 5.2173 (9) ÅCell parameters from 2503 reflections
b = 8.7011 (15) Åθ = 2.5–27.6°
c = 11.1453 (19) ŵ = 0.13 mm1
α = 75.545 (2)°T = 293 K
β = 81.854 (2)°Block, colorless
γ = 76.427 (2)°0.28 × 0.24 × 0.16 mm
V = 474.40 (14) Å3
Data collection top
Bruker APEXII CCD
diffractometer
2141 independent reflections
Radiation source: fine-focus sealed tube1816 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.026
ϕ and ω scansθmax = 27.6°, θmin = 1.9°
Absorption correction: multi-scan
(SADABS; Sheldrick, 2003)
h = 66
Tmin = 0.964, Tmax = 0.980k = 1111
4155 measured reflectionsl = 1413
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)] = 0.043Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.140H-atom parameters constrained
S = 1.06 w = 1/[σ2(Fo2) + (0.0825P)2 + 0.0701P]
where P = (Fo2 + 2Fc2)/3
2141 reflections(Δ/σ)max < 0.001
145 parametersΔρmax = 0.29 e Å3
0 restraintsΔρmin = 0.23 e Å3
Crystal data top
C10H6F2N4γ = 76.427 (2)°
Mr = 220.19V = 474.40 (14) Å3
Triclinic, P1Z = 2
a = 5.2173 (9) ÅMo Kα radiation
b = 8.7011 (15) ŵ = 0.13 mm1
c = 11.1453 (19) ÅT = 293 K
α = 75.545 (2)°0.28 × 0.24 × 0.16 mm
β = 81.854 (2)°
Data collection top
Bruker APEXII CCD
diffractometer
2141 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2003)
1816 reflections with I > 2σ(I)
Tmin = 0.964, Tmax = 0.980Rint = 0.026
4155 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0430 restraints
wR(F2) = 0.140H-atom parameters constrained
S = 1.06Δρmax = 0.29 e Å3
2141 reflectionsΔρmin = 0.23 e Å3
145 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*/Ueq
C10.5584 (3)0.24423 (15)0.57193 (12)0.0414 (3)
C20.1573 (3)0.09578 (15)0.89446 (12)0.0403 (3)
C30.3758 (2)0.16100 (14)0.65684 (11)0.0359 (3)
C40.4178 (2)0.00938 (14)0.67660 (11)0.0382 (3)
C50.2446 (3)0.09029 (14)0.75315 (12)0.0389 (3)
C60.0223 (2)0.00551 (14)0.81451 (11)0.0359 (3)
C70.0247 (2)0.16328 (14)0.79859 (11)0.0348 (3)
C80.1573 (2)0.24965 (14)0.71567 (11)0.0355 (3)
C90.2521 (3)0.41626 (17)0.85819 (15)0.0548 (4)
H9A0.15100.42060.92350.066*
H9B0.43470.46810.87600.066*
C100.1447 (3)0.50503 (16)0.73570 (16)0.0539 (4)
H10A0.26510.51950.67310.065*
H10B0.12880.61150.74210.065*
F10.63601 (16)0.08862 (10)0.61981 (8)0.0525 (3)
F20.28294 (18)0.25305 (9)0.77522 (9)0.0548 (3)
N10.6992 (3)0.31503 (17)0.50478 (13)0.0574 (4)
N20.3029 (3)0.16595 (16)0.95803 (12)0.0560 (3)
N30.1134 (2)0.41386 (13)0.69902 (12)0.0481 (3)
H30.20660.46070.63680.058*
N40.2375 (2)0.24862 (13)0.85611 (11)0.0463 (3)
H40.35000.20050.90650.056*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0426 (7)0.0361 (6)0.0434 (7)0.0099 (5)0.0025 (5)0.0070 (5)
C20.0442 (7)0.0324 (6)0.0425 (7)0.0105 (5)0.0031 (5)0.0029 (5)
C30.0368 (6)0.0330 (6)0.0366 (6)0.0104 (5)0.0008 (5)0.0046 (5)
C40.0385 (6)0.0328 (6)0.0413 (6)0.0054 (5)0.0013 (5)0.0093 (5)
C50.0450 (7)0.0263 (5)0.0438 (7)0.0075 (5)0.0038 (5)0.0050 (5)
C60.0384 (6)0.0307 (6)0.0372 (6)0.0106 (5)0.0021 (5)0.0029 (5)
C70.0348 (6)0.0307 (6)0.0367 (6)0.0080 (4)0.0009 (5)0.0038 (4)
C80.0374 (6)0.0290 (6)0.0389 (6)0.0091 (4)0.0014 (5)0.0043 (4)
C90.0552 (8)0.0362 (7)0.0657 (9)0.0042 (6)0.0124 (7)0.0132 (6)
C100.0528 (8)0.0307 (6)0.0715 (10)0.0053 (5)0.0069 (7)0.0091 (6)
F10.0486 (5)0.0416 (4)0.0609 (5)0.0030 (3)0.0120 (4)0.0149 (4)
F20.0620 (5)0.0262 (4)0.0709 (6)0.0087 (3)0.0058 (4)0.0084 (4)
N10.0592 (8)0.0508 (7)0.0578 (7)0.0212 (6)0.0136 (6)0.0053 (6)
N20.0555 (7)0.0487 (7)0.0587 (7)0.0205 (6)0.0065 (6)0.0002 (6)
N30.0470 (6)0.0279 (5)0.0627 (7)0.0106 (4)0.0132 (5)0.0051 (5)
N40.0420 (6)0.0344 (5)0.0564 (7)0.0093 (4)0.0126 (5)0.0075 (5)
Geometric parameters (Å, º) top
C1—N11.1425 (17)C7—C81.4354 (16)
C1—C31.4330 (17)C8—N31.3618 (16)
C2—N21.1408 (17)C9—N41.4485 (18)
C2—C61.4310 (17)C9—C101.495 (2)
C3—C81.3973 (17)C9—H9A0.9700
C3—C41.4116 (17)C9—H9B0.9700
C4—F11.3481 (14)C10—N31.4537 (18)
C4—C51.3492 (18)C10—H10A0.9700
C5—F21.3465 (14)C10—H10B0.9700
C5—C61.4081 (18)N3—H30.8600
C6—C71.4007 (16)N4—H40.8599
C7—N41.3580 (16)
N1—C1—C3177.89 (14)C3—C8—C7118.45 (11)
N2—C2—C6179.11 (14)N4—C9—C10110.40 (12)
C8—C3—C4121.41 (11)N4—C9—H9A109.6
C8—C3—C1119.68 (11)C10—C9—H9A109.6
C4—C3—C1118.89 (11)N4—C9—H9B109.6
F1—C4—C5121.20 (11)C10—C9—H9B109.6
F1—C4—C3118.67 (11)H9A—C9—H9B108.1
C5—C4—C3120.12 (11)N3—C10—C9109.85 (12)
F2—C5—C4121.21 (11)N3—C10—H10A109.7
F2—C5—C6118.54 (11)C9—C10—H10A109.7
C4—C5—C6120.23 (11)N3—C10—H10B109.7
C7—C6—C5121.40 (11)C9—C10—H10B109.7
C7—C6—C2120.11 (11)H10A—C10—H10B108.2
C5—C6—C2118.48 (11)C8—N3—C10120.46 (11)
N4—C7—C6122.84 (11)C8—N3—H3114.4
N4—C7—C8118.78 (11)C10—N3—H3118.1
C6—C7—C8118.36 (11)C7—N4—C9121.10 (11)
N3—C8—C3122.59 (11)C7—N4—H4121.1
N3—C8—C7118.94 (11)C9—N4—H4116.3
C8—C3—C4—F1178.24 (11)C4—C3—C8—N3179.46 (12)
C1—C3—C4—F13.43 (18)C1—C3—C8—N32.24 (19)
C1—C3—C4—C5177.99 (11)C4—C3—C8—C70.62 (19)
F1—C4—C5—F20.2 (2)C1—C3—C8—C7178.93 (10)
C3—C4—C5—F2178.78 (11)N4—C7—C8—N31.12 (19)
F1—C4—C5—C6178.02 (11)C6—C7—C8—N3179.76 (11)
C3—C4—C5—C60.5 (2)N4—C7—C8—C3180.00 (11)
F2—C5—C6—C7178.04 (11)C6—C7—C8—C31.37 (18)
C4—C5—C6—C70.3 (2)N4—C9—C10—N350.23 (18)
F2—C5—C6—C21.96 (18)C3—C8—N3—C10164.48 (13)
C4—C5—C6—C2179.72 (11)C7—C8—N3—C1016.7 (2)
C5—C6—C7—N4179.80 (11)C9—C10—N3—C841.7 (2)
C2—C6—C7—N40.20 (19)C6—C7—N4—C9167.19 (13)
C5—C6—C7—C81.22 (19)C8—C7—N4—C914.2 (2)
C2—C6—C7—C8178.78 (10)C10—C9—N4—C739.5 (2)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N3—H3···N1i0.862.293.075 (2)152
N4—H4···N2ii0.862.213.0358 (19)160
Symmetry codes: (i) x+1, y+1, z+1; (ii) x1, y, z+2.

Experimental details

Crystal data
Chemical formulaC10H6F2N4
Mr220.19
Crystal system, space groupTriclinic, P1
Temperature (K)293
a, b, c (Å)5.2173 (9), 8.7011 (15), 11.1453 (19)
α, β, γ (°)75.545 (2), 81.854 (2), 76.427 (2)
V3)474.40 (14)
Z2
Radiation typeMo Kα
µ (mm1)0.13
Crystal size (mm)0.28 × 0.24 × 0.16
Data collection
DiffractometerBruker APEXII CCD
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 2003)
Tmin, Tmax0.964, 0.980
No. of measured, independent and
observed [I > 2σ(I)] reflections
4155, 2141, 1816
Rint0.026
(sin θ/λ)max1)0.652
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.043, 0.140, 1.06
No. of reflections2141
No. of parameters145
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.29, 0.23

Computer programs: APEX2 (Bruker, 2007), SAINT (Bruker, 2007), SHELXTL (Sheldrick, 2008) and DIAMOND (Brandenburg, 2005).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N3—H3···N1i0.862.293.075 (2)152
N4—H4···N2ii0.862.213.0358 (19)160
Symmetry codes: (i) x+1, y+1, z+1; (ii) x1, y, z+2.
 

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.  CrossRef Web of Science
First citationBrandenburg, K. (2005). DIAMOND. Crystal Impact GbR, Bonn, Germany.
First citationBruker (2007). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.
First citationEtter, M. C. (1990). Acc. Chem. Res. 23, 120–126.  CrossRef CAS Web of Science
First citationMeazza, G., Bettarini, F. & Fornara, L. (2007). WO Patent No. 2007101587.
First citationOrthaber, A., Seidel, C., Belaj, F., Albering, J. H., Pietschnig, R. & Ruschewitz, U. (2010). Inorg. Chem. 49, 9350–9357.  Web of Science CSD CrossRef CAS PubMed
First citationSheldrick, G. M. (2003). SADABS. University of Göttingen, Germany.
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals

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