Quinoxaline-2-carbonitrile

Abstract

In the title compound, C₉H₅N₃, the quinoxaline ring is essentially planar, with a maximum deviation of 0.012 (1) Å. Short inter­molecular distances between the centroids of the 2,3-dihydro­pyrazine and benzene rings [3.6490 (5) Å] indicate the existence of π⋯π inter­actions. In the crystal packing, the mol­ecules are linked via two pairs of inter­molecular C—H⋯N inter­actions, forming R ² ₂ (8) and R ² ₂ (10) ring motifs; these mol­ecules are further linked into a two-dimensional network parallel to (1 0 2) via another C–H⋯N inter­action.

Related literature

For the synthesis of cyano N-heterocyclic compounds, see: Goswami et al. (2007 ▶, 2009 ▶). For reference bond lengths, see: Allen et al. (1987 ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶). For the stability of the temperature controller used for the data collection, see: Cosier & Glazer (1986 ▶).

Experimental

Crystal data

• C₉H₅N₃

• M _r = 155.16

• Monoclinic,

• a = 3.8055 (1) Å

• b = 19.0466 (4) Å

• c = 10.1845 (2) Å

• β = 93.466 (1)°

• V = 736.84 (3) ų

• Z = 4

• Mo Kα radiation

• μ = 0.09 mm⁻¹

• T = 100 K

• 0.39 × 0.28 × 0.25 mm

Data collection

• Bruker SMART APEXII CCD area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.966, T _max = 0.978

• 11604 measured reflections

• 2716 independent reflections

• 2183 reflections with I > 2σ(I)

• R _int = 0.023

Refinement

• R[F ² > 2σ(F ²)] = 0.047

• wR(F ²) = 0.135

• S = 1.08

• 2716 reflections

• 129 parameters

• All H-atom parameters refined

• Δρ_max = 0.53 e Å⁻³

• Δρ_min = −0.23 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT (Bruker, 2005 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ▶).

Supplementary Material

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C2—H2⋯N1i	0.984 (14)	2.619 (14)	3.5730 (12)	163.4 (12)
C4—H4⋯N2ii	0.988 (13)	2.593 (13)	3.4268 (12)	142.0 (10)
C7—H7⋯N3iii	0.998 (14)	2.540 (15)	3.5225 (12)	168.3 (12)

Symmetry codes: (i) ; (ii) ; (iii) .

supplementary crystallographic information

Comment

Heterocyclic molecules containing a cyano group are useful as drug intermediates. The development of new pathways leading to efficient synthesis of heterocycles with diversity in skeleton and functional groups is an important field of research in both synthetic and medicinal chemistry. Recently, we have synthesized a number of cyano N-heterocyclic compounds using triselenium dicyanide (TSD) (Goswami et al., 2007, 2009). Herein we report the synthesis of 2-cyanoquinoxaline from quinoxaline under microwave irradiation and its molecular structure.

The bond lengths (Allen et al., 1987) and angles in the title compound (Fig. 1) are within normal ranges. The quinoxaline ring (N1/N2/C1-C8) is essentially planar, with the maximum deviation of 0.012 (1) Å for atom C5. Short intermolecular distances between the centroids of the pyrazine (N1/N2/C1/C6-C8) and benzene rings (C1-C6) [3.6490 (5) Å] indicate the existence of π···π interactions.

In the crystal packing (Fig. 2), the molecules are linked via pairs of intermolecular C2—H2···N1 and C7—H7···N3 interactions, forming R²₂ (8) and R²₂ (10) ring motifs (Bernstein et al., 1995) and these molecules are further linked into two-dimensional networks parallel to plane (1 0 2) via C4–H4···N2 interactions.

Experimental

A thoroughly ground mixture of selenium dioxide (1.32 g, 12 mmol) and malononitrile (0.26 g, 4 mmol) in 4-5 drops of DMSO was kept stirring in an open-mouth conical flask. The mixture became reddish-brown after 7 min. An exothermic reaction began in the next 10 minutes when triselenium dicyanide was formed. The heterocyclic substrate quinoxaline (0.39 g, 3 mmol) was added to the mixture after the termination of the exothermic reaction. The conical flask was placed in a domestic microwave oven at 240 W for 20 min. The progress of the reaction was monitored by TLC. After completion of the reaction, water was added and the mixture was extracted with chloroform. The organic layer was washed with saturated brine and dried over MgSO₄ and followed by evaporation with a rotary evaporator under low pressure to afford a light yellow substance. This was purified on silica gel (60-120 mesh) column chromatography eluting with petroleum ether (boiling point, 60-80° C) to give the compound (0.34 g, 74 %) as a crystalline solid.

Refinement

All H atoms were located in a difference Fourier map and refined freely.

Figures

Fig. 1.

The molecular structure of the title compound, showing 50% probability displacement ellipsoids for non-H atoms and the atom-numbering scheme.

Fig. 2.

The crystal structure of the title compound viewed along the a axis. Intermolecular interactions are shown in dashed lines.

Crystal data

C9H5N3	F(000) = 320
Mr = 155.16	Dx = 1.399 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 4710 reflections
a = 3.8055 (1) Å	θ = 2.9–32.7°
b = 19.0466 (4) Å	µ = 0.09 mm−1
c = 10.1845 (2) Å	T = 100 K
β = 93.466 (1)°	Block, yellow
V = 736.84 (3) Å3	0.39 × 0.28 × 0.25 mm
Z = 4

Data collection

Bruker SMART APEXII CCD area-detector diffractometer	2716 independent reflections
Radiation source: fine-focus sealed tube	2183 reflections with I > 2σ(I)
graphite	Rint = 0.023
φ and ω scans	θmax = 32.8°, θmin = 2.1°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −5→5
Tmin = 0.966, Tmax = 0.978	k = −29→21
11604 measured reflections	l = −15→14

Refinement

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)] = 0.047	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.135	All H-atom parameters refined
S = 1.08	w = 1/[σ2(Fo2) + (0.0782P)2 + 0.0918P] where P = (Fo2 + 2Fc2)/3
2716 reflections	(Δ/σ)max = 0.001
129 parameters	Δρmax = 0.53 e Å−3
0 restraints	Δρmin = −0.23 e Å−3

Special details

Experimental. The crystal was placed in the cold stream of an Oxford Cyrosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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 (Ų)

	x	y	z	Uiso*/Ueq
N1	0.12156 (18)	0.46098 (4)	0.84114 (7)	0.01481 (16)
N2	−0.12366 (19)	0.33470 (4)	0.71846 (8)	0.01659 (17)
N3	−0.2187 (2)	0.57757 (5)	0.60971 (9)	0.0269 (2)
C1	0.1884 (2)	0.39728 (4)	0.89844 (8)	0.01344 (17)
C2	0.3822 (2)	0.39456 (5)	1.02181 (9)	0.01744 (18)
C3	0.4514 (2)	0.33059 (5)	1.07937 (10)	0.02033 (19)
C4	0.3352 (2)	0.26756 (5)	1.01678 (10)	0.0210 (2)
C5	0.1474 (2)	0.26871 (5)	0.89805 (9)	0.01857 (19)
C6	0.0674 (2)	0.33382 (4)	0.83638 (9)	0.01441 (17)
C7	−0.1868 (2)	0.39663 (4)	0.66474 (9)	0.01675 (18)
C8	−0.0633 (2)	0.45941 (4)	0.72702 (8)	0.01496 (17)
C9	−0.1450 (2)	0.52598 (5)	0.66332 (9)	0.01913 (19)
H2	0.471 (4)	0.4375 (7)	1.0662 (14)	0.030 (3)*
H3	0.591 (4)	0.3282 (7)	1.1650 (16)	0.038 (4)*
H4	0.396 (3)	0.2229 (7)	1.0622 (13)	0.028 (3)*
H5	0.057 (4)	0.2262 (7)	0.8533 (14)	0.032 (3)*
H7	−0.328 (4)	0.4008 (7)	0.5793 (14)	0.028 (3)*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
N1	0.0154 (3)	0.0145 (3)	0.0146 (3)	0.0003 (2)	0.0014 (2)	0.0010 (2)
N2	0.0168 (3)	0.0173 (3)	0.0157 (4)	−0.0006 (2)	0.0014 (3)	−0.0016 (3)
N3	0.0328 (4)	0.0235 (4)	0.0241 (5)	0.0028 (3)	−0.0002 (3)	0.0057 (3)
C1	0.0128 (3)	0.0147 (3)	0.0130 (4)	0.0002 (2)	0.0019 (3)	0.0004 (3)
C2	0.0157 (4)	0.0218 (4)	0.0147 (4)	−0.0004 (3)	−0.0002 (3)	0.0005 (3)
C3	0.0164 (4)	0.0275 (4)	0.0170 (4)	0.0019 (3)	0.0003 (3)	0.0055 (3)
C4	0.0176 (4)	0.0208 (4)	0.0248 (5)	0.0030 (3)	0.0042 (3)	0.0088 (3)
C5	0.0179 (4)	0.0147 (4)	0.0235 (5)	0.0007 (3)	0.0036 (3)	0.0029 (3)
C6	0.0131 (3)	0.0152 (3)	0.0151 (4)	0.0000 (2)	0.0027 (3)	0.0000 (3)
C7	0.0164 (4)	0.0195 (4)	0.0142 (4)	−0.0003 (3)	0.0000 (3)	−0.0004 (3)
C8	0.0145 (3)	0.0168 (4)	0.0137 (4)	0.0005 (3)	0.0019 (3)	0.0015 (3)
C9	0.0204 (4)	0.0202 (4)	0.0167 (4)	0.0005 (3)	0.0005 (3)	0.0015 (3)

Geometric parameters (Å, °)

N1—C8	1.3220 (11)	C3—C4	1.4175 (14)
N1—C1	1.3636 (10)	C3—H3	0.995 (16)
N2—C7	1.3161 (11)	C4—C5	1.3670 (13)
N2—C6	1.3659 (11)	C4—H4	0.988 (13)
N3—C9	1.1506 (12)	C5—C6	1.4150 (11)
C1—C2	1.4190 (12)	C5—H5	0.980 (14)
C1—C6	1.4273 (11)	C7—C8	1.4202 (12)
C2—C3	1.3706 (12)	C7—H7	0.997 (14)
C2—H2	0.985 (14)	C8—C9	1.4495 (12)
C8—N1—C1	115.57 (7)	C4—C5—C6	119.57 (8)
C7—N2—C6	116.78 (7)	C4—C5—H5	123.2 (8)
N1—C1—C2	119.01 (7)	C6—C5—H5	117.2 (8)
N1—C1—C6	121.14 (8)	N2—C6—C5	119.33 (7)
C2—C1—C6	119.85 (7)	N2—C6—C1	121.28 (7)
C3—C2—C1	119.16 (8)	C5—C6—C1	119.38 (8)
C3—C2—H2	119.4 (8)	N2—C7—C8	121.44 (8)
C1—C2—H2	121.5 (8)	N2—C7—H7	120.7 (7)
C2—C3—C4	120.92 (9)	C8—C7—H7	117.9 (7)
C2—C3—H3	119.6 (8)	N1—C8—C7	123.77 (7)
C4—C3—H3	119.4 (8)	N1—C8—C9	117.52 (7)
C5—C4—C3	121.10 (8)	C7—C8—C9	118.71 (8)
C5—C4—H4	121.5 (8)	N3—C9—C8	177.49 (10)
C3—C4—H4	117.4 (8)
C8—N1—C1—C2	−179.34 (7)	C4—C5—C6—C1	0.84 (13)
C8—N1—C1—C6	0.75 (12)	N1—C1—C6—N2	−0.95 (13)
N1—C1—C2—C3	−179.68 (8)	C2—C1—C6—N2	179.14 (7)
C6—C1—C2—C3	0.24 (13)	N1—C1—C6—C5	178.94 (7)
C1—C2—C3—C4	0.62 (13)	C2—C1—C6—C5	−0.97 (12)
C2—C3—C4—C5	−0.75 (14)	C6—N2—C7—C8	−0.32 (13)
C3—C4—C5—C6	0.00 (14)	C1—N1—C8—C7	−0.38 (12)
C7—N2—C6—C5	−179.20 (7)	C1—N1—C8—C9	179.15 (7)
C7—N2—C6—C1	0.69 (12)	N2—C7—C8—N1	0.18 (14)
C4—C5—C6—N2	−179.26 (7)	N2—C7—C8—C9	−179.36 (8)

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2···N1i	0.984 (14)	2.619 (14)	3.5730 (12)	163.4 (12)
C4—H4···N2ii	0.988 (13)	2.593 (13)	3.4268 (12)	142.0 (10)
C7—H7···N3iii	0.998 (14)	2.540 (15)	3.5225 (12)	168.3 (12)

Symmetry codes: (i) −x+1, −y+1, −z+2; (ii) x+1, −y+1/2, z+1/2; (iii) −x−1, −y+1, −z+1.