2,6-Dichloro­pyridine-3,5-dicarbonitrile

Woiczechowski-Pop, A.; Varga, R.A.; Terec, A.; Grosu, I.

doi:10.1107/S160053681003758X

organic compounds

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ISSN: 2056-9890

Volume 66| Part 10| October 2010| Page o2638

doi:10.1107/S160053681003758X

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2,6-Dichloropyridine-3,5-dicarbonitrile

Adrian Woiczechowski-Pop,^a ^* Richard A. Varga,^b Anamaria Terec ^a and Ion Grosu ^a

^aOrganic Chemistry Department, Faculty of Chemistry and Chemical Engineering, Babes Bolyai University, Arany Janos 11, 400028, Cluj Napoca, Romania, and ^bInorganic Chemistry Department, Faculty of Chemistry and Chemical Engineering, Babes Bolyai University, Arany Janos 11, 400028, Cluj Napoca, Romania
^*Correspondence e-mail: wadrian@chem.ubbcluj.ro

(Received 11 August 2010; accepted 20 September 2010; online 25 September 2010)

In the crystal, essentially planar (r.m.s. deviation = 0.003 Å) molecules of the title compound, C₇HCl₂N₃, form chains along the b axis by means of C—H⋯N interactions. These chains are further linked into layers parallel to the ab plane by C—Cl⋯N interactions.

Related literature

For the structures of related pyridine derivatives, see: Boer et al. (1972 ); Clegg et al. (1997 ); Julia et al. (1983 ); Schlosser et al. (2006 ); Schmidt et al. (2005 ); Smith et al. (2008 ). For more information on the synthesis of 2,6-dichloropyridine-3,5-dicarbonitrile, see: Duindam et al. (1993 ). For compounds obtained from 2,6-dichloropyridine-3,5-dicarbonitrile, see: Katz et al. (2005 ); Vilarelle et al. (2004 ).

Experimental

Crystal data

C₇HCl₂N₃
M_r = 198.01
Orthorhombic, P b c a
a = 6.8473 (9) Å
b = 12.1307 (15) Å
c = 19.430 (3) Å
V = 1613.9 (4) Å³
Z = 8
Mo Kα radiation
μ = 0.74 mm⁻¹
T = 297 K
0.41 × 0.39 × 0.39 mm

Data collection

Bruker SMART APEX CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2000 ) T_min = 0.751, T_max = 0.761
10614 measured reflections
1420 independent reflections
1328 reflections with I > 2σ(I)
R_int = 0.049

Refinement

R[F² > 2σ(F²)] = 0.067
wR(F²) = 0.133
S = 1.29
1420 reflections
109 parameters
H-atom parameters constrained
Δρ_max = 0.25 e Å⁻³
Δρ_min = −0.33 e Å⁻³

Table 1
Intermolecular interactions (Å, °)

D—X⋯A	D—X	X⋯A	D⋯A	D—X⋯A
C3—H3⋯N1ⁱ	0.93	2.54	3.412 (5)	157
C1—Cl1⋯N2ⁱⁱ	1.71 (1)	3.24 (1)	4.820 (5)	152 (1)
C5—Cl2⋯N3ⁱⁱⁱ	1.72 (1)	3.28 (1)	4.851 (6)	151 (1)
Symmetry codes: (i) $[-x+{\script{3\over 2}}, y-{\script{1\over 2}}, z]$ ; (ii) $[-x+{\script{5\over 2}}, y+{\script{1\over 2}}, z]$ ; (iii) $[-x+{\script{1\over 2}}, y+{\script{1\over 2}}, z]$ .

Data collection: SMART (Bruker, 2000); cell refinement: SAINT-Plus (Bruker, 2001 ); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2006 ); software used to prepare material for publication: publCIF (Westrip, 2010 ).

Supporting information

Crystal structure: contains datablocks I, New_Global_Publ_Block. DOI: 10.1107/S160053681003758X/ya2129sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S160053681003758X/ya2129Isup2.hkl

checkCIF report

Comment top

Some pyridine derivatives are known to be important intermediates in pharmaceutical and medicinal chemistry. They can be used for the synthesis of various compounds having antibacterial, antianaphilactic, antipyretic, antiallergic or anticancer properties (Vilarelle et al., 2004). Lately, pyridine derivatives were used in the synthesis of cage molecules, supramolecular structures which are important as tools for the study of molecular encapsulation and host–guest interactions (Katz et al., 2005).

Relatively few crystal structures of pyridines substituted in positions 2 and 6 with chlorine atoms were published (Boer et al., 1972; Clegg et al., 1997; Julia et al., 1983; Schlosser et al., 2006; Schmidt et al., 2005; Smith et al., 2008). The synthesis of the title compound has been reported some years ago (Duindam et al., 1993), however its crystal structure has not yet been determined, even though electron withdrawing CN groups, causing considerable acidity of the H atom in position 4, as well as chlorine substituents at the pyridine atoms adjacent to the endocyclic N atom, may give rise to important non-conventional intermolecular interactions. Therefore, one may expect that structural study of the title compound may provide some non-trivial information.

Molecule of the title compound (Fig. 1) is essentially planar; the N2 and N3 atoms deviate from the pyridine plane by 0.060 (4) Å and 0.026 (4) Å respectively.

The molecules are linked by means of C3—H3···N1ⁱ ineractions (Table 1) into infinite chains running along the b axis. The pyridine rings in the adjacent molecules of these chains are not coplanar, but rather form substantial dihedral angle with one another [56.5 (1)°]. The chains are further linked via C1—Cl1···N2ⁱⁱ and C5—Cl2···N3ⁱⁱⁱ interactions into layers parallel to the ab-plane (Table 1; Fig. 2).

Related literature top

For the structures of related pyridine derivatives, see: Boer et al. (1972); Clegg et al. (1997); Julia et al. (1983); Schlosser et al. (2006); Schmidt et al. (2005); Smith et al. (2008). For more information on the synthesis of 2,6-dichloropyridine-3,5-dicarbonitrile, see: Duindam et al. (1993). For compounds obtained from 2,6-dichloropyridine-3,5-dicarbonitrile, see: Katz et al. (2005); Vilarelle et al. (2004).

Experimental top

A mixture of malononitrile (5 g, 75.69 mmol, 2 equiv.), triethyl orthoformate (5.61 g, 37.84 mmol, 1 equiv.) and pyridine (2.99 g, 37.84 mmol, 1 equiv.) was allowed to reflux for 20 minutes, then concentrated HCl was added at 80°C. The mixture was cooled to room temperature and water (20 ml) was added. The formed precipitate was collected by filtration, washed successively with water, ethanol and diethylether to afford the intermediate 2-amino-6-chloropyridine-3,5-dicarbonitrile (9.74 g, 96%). To a solution of 2-amino-6-chloropyridine-3,5-dicarbonitrile (3 g, 16.8 mmol, 1 equiv.) and CuCl₂ (3.39 g, 25.2 mmol, 1.5 equiv.) in dry CH₃CN (150 ml), isopentyl nitrite was added (2.95 g, 25.2 mmol, 1.5 equiv.). The mixture was heated at 65°C for 5 h. The solution was acidified (HCl, 2 N) to pH=3, extracted with CH₂Cl₂ (3×50 ml) and dried with Na₂SO₄. The solvent was removed under reduced pressure and the crude product was purified by flash chromatography using CH₂Cl₂ as eluent to yield 2,6-dichloropyridine-3,5-dicarbonitrile as a colourless solid (2.97 g, 89%). The crystals were obtained by slow evaporation of the solvent from solution of the title compound in dichloromethane.

Computing details top

Data collection: SMART (Bruker, 2000); cell refinement: SAINT-Plus (Bruker, 2001); data reduction: SAINT-Plus (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top

	Fig. 1. Molecular structure of the title compound; displacement ellipsoids are drawn at the 50% probability level, and the H3 atom is shown as a circle of arbitrary small radius.
	Fig. 2. Packing diagram for the crystal of the title compound viewed down the b axis. The C—H···N and Cl···N interactions are shown as dashed lines.

2,6-Dichloropyridine-3,5-dicarbonitrile top

Crystal data top

C₇HCl₂N₃	F(000) = 784
M_r = 198.01	D_x = 1.630 Mg m⁻³
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 4078 reflections
a = 6.8473 (9) Å	θ = 3.1–26.1°
b = 12.1307 (15) Å	µ = 0.74 mm⁻¹
c = 19.430 (3) Å	T = 297 K
V = 1613.9 (4) Å³	Block, colourless
Z = 8	0.41 × 0.39 × 0.39 mm

Data collection top

Bruker SMART APEX CCD area-detector diffractometer	1420 independent reflections
Radiation source: fine-focus sealed tube	1328 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.049
phi and ω scans	θ_max = 25.0°, θ_min = 2.1°
Absorption correction: multi-scan (SADABS; Bruker, 2000)	h = −8→8
T_min = 0.751, T_max = 0.761	k = −14→14
10614 measured reflections	l = −23→23

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)] = 0.067	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.133	H-atom parameters constrained
S = 1.29	w = 1/[σ²(F_o²) + (0.0317P)² + 2.8365P] where P = (F_o² + 2F_c²)/3
1420 reflections	(Δ/σ)_max < 0.001
109 parameters	Δρ_max = 0.25 e Å⁻³
0 restraints	Δρ_min = −0.33 e Å⁻³

Crystal data top

C₇HCl₂N₃	V = 1613.9 (4) Å³
M_r = 198.01	Z = 8
Orthorhombic, Pbca	Mo Kα radiation
a = 6.8473 (9) Å	µ = 0.74 mm⁻¹
b = 12.1307 (15) Å	T = 297 K
c = 19.430 (3) Å	0.41 × 0.39 × 0.39 mm

Data collection top

Bruker SMART APEX CCD area-detector diffractometer	1420 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2000)	1328 reflections with I > 2σ(I)
T_min = 0.751, T_max = 0.761	R_int = 0.049
10614 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.067	0 restraints
wR(F²) = 0.133	H-atom parameters constrained
S = 1.29	Δρ_max = 0.25 e Å⁻³
1420 reflections	Δρ_min = −0.33 e Å⁻³
109 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
C1	0.9151 (5)	0.3589 (3)	0.4007 (2)	0.0375 (9)
C2	0.8734 (5)	0.2479 (3)	0.40946 (19)	0.0364 (9)
C3	0.7015 (5)	0.2084 (3)	0.38179 (18)	0.0368 (9)
H3	0.6687	0.1343	0.3861	0.044*
C4	0.5791 (5)	0.2801 (3)	0.34764 (18)	0.0332 (8)
C5	0.6383 (6)	0.3884 (3)	0.34168 (19)	0.0390 (9)
C6	1.0034 (6)	0.1770 (4)	0.4467 (2)	0.0474 (10)
C7	0.3992 (6)	0.2425 (3)	0.3184 (2)	0.0438 (10)
Cl1	1.12351 (16)	0.41416 (10)	0.43512 (6)	0.0578 (4)
Cl2	0.49486 (18)	0.48205 (10)	0.29881 (6)	0.0604 (4)
N1	0.8014 (5)	0.4280 (3)	0.36795 (16)	0.0404 (8)
N2	1.1049 (6)	0.1222 (3)	0.4775 (2)	0.0683 (12)
N3	0.2550 (6)	0.2128 (4)	0.29590 (19)	0.0630 (11)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.033 (2)	0.040 (2)	0.039 (2)	−0.0043 (18)	0.0058 (17)	−0.0067 (17)
C2	0.035 (2)	0.0368 (19)	0.0372 (19)	0.0031 (18)	−0.0002 (16)	−0.0039 (17)
C3	0.042 (2)	0.0271 (18)	0.041 (2)	−0.0021 (17)	0.0037 (18)	−0.0046 (16)
C4	0.0343 (19)	0.0314 (19)	0.0339 (19)	0.0003 (16)	0.0020 (16)	−0.0033 (15)
C5	0.041 (2)	0.037 (2)	0.039 (2)	0.0048 (18)	0.0058 (18)	0.0025 (17)
C6	0.048 (2)	0.047 (2)	0.048 (2)	0.003 (2)	−0.003 (2)	−0.009 (2)
C7	0.048 (2)	0.041 (2)	0.042 (2)	−0.001 (2)	−0.003 (2)	−0.0012 (18)
Cl1	0.0412 (6)	0.0622 (7)	0.0699 (8)	−0.0128 (5)	−0.0045 (5)	−0.0138 (6)
Cl2	0.0611 (7)	0.0487 (6)	0.0714 (8)	0.0081 (6)	−0.0105 (6)	0.0191 (5)
N1	0.0417 (19)	0.0334 (17)	0.0461 (19)	−0.0030 (15)	0.0061 (16)	−0.0011 (15)
N2	0.067 (3)	0.064 (3)	0.074 (3)	0.025 (2)	−0.020 (2)	−0.007 (2)
N3	0.054 (2)	0.075 (3)	0.060 (2)	−0.014 (2)	−0.013 (2)	0.002 (2)

Geometric parameters (Å, º) top

C1—N1	1.309 (5)	C4—C5	1.380 (5)
C1—C2	1.387 (5)	C4—C7	1.430 (5)
C1—Cl1	1.713 (4)	C5—N1	1.319 (5)
C2—C3	1.380 (5)	C5—Cl2	1.717 (4)
C2—C6	1.434 (6)	C6—N2	1.133 (5)
C3—C4	1.378 (5)	C7—N3	1.139 (5)
C3—H3	0.9300

N1—C1—C2	124.0 (4)	C3—C4—C5	117.6 (3)
N1—C1—Cl1	115.8 (3)	C3—C4—C7	120.9 (3)
C2—C1—Cl1	120.2 (3)	C5—C4—C7	121.6 (3)
C3—C2—C1	117.7 (3)	N1—C5—C4	124.3 (4)
C3—C2—C6	121.2 (4)	N1—C5—Cl2	115.5 (3)
C1—C2—C6	121.1 (4)	C4—C5—Cl2	120.2 (3)
C4—C3—C2	119.1 (3)	N2—C6—C2	178.4 (5)
C4—C3—H3	120.4	N3—C7—C4	179.2 (5)
C2—C3—H3	120.4	C1—N1—C5	117.3 (3)

N1—C1—C2—C3	0.1 (6)	C3—C4—C5—N1	−1.8 (6)
Cl1—C1—C2—C3	178.7 (3)	C7—C4—C5—N1	179.4 (4)
N1—C1—C2—C6	−179.2 (4)	C3—C4—C5—Cl2	179.1 (3)
Cl1—C1—C2—C6	−0.6 (5)	C7—C4—C5—Cl2	0.3 (5)
C1—C2—C3—C4	−0.6 (5)	C2—C1—N1—C5	−0.3 (6)
C6—C2—C3—C4	178.7 (4)	Cl1—C1—N1—C5	−179.0 (3)
C2—C3—C4—C5	1.4 (5)	C4—C5—N1—C1	1.2 (6)
C2—C3—C4—C7	−179.8 (3)	Cl2—C5—N1—C1	−179.6 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3···N1ⁱ	0.93	2.54	3.412 (5)	157
C1—Cl1···N2ⁱⁱ	1.71 (1)	3.24 (1)	4.820 (5)	152 (1)
C5—Cl2···N3ⁱⁱⁱ	1.72 (1)	3.28 (1)	4.851 (6)	151 (1)

Symmetry codes: (i) −x+3/2, y−1/2, z; (ii) −x+5/2, y+1/2, z; (iii) −x+1/2, y+1/2, z.

Experimental details

Crystal data
Chemical formula	C₇HCl₂N₃
M_r	198.01
Crystal system, space group	Orthorhombic, Pbca
Temperature (K)	297
a, b, c (Å)	6.8473 (9), 12.1307 (15), 19.430 (3)
V (Å³)	1613.9 (4)
Z	8
Radiation type	Mo Kα
µ (mm⁻¹)	0.74
Crystal size (mm)	0.41 × 0.39 × 0.39

Data collection
Diffractometer	Bruker SMART APEX CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2000)
T_min, T_max	0.751, 0.761
No. of measured, independent and observed [I > 2σ(I)] reflections	10614, 1420, 1328
R_int	0.049
(sin θ/λ)_max (Å⁻¹)	0.595

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.067, 0.133, 1.29
No. of reflections	1420
No. of parameters	109
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.25, −0.33

Computer programs: SMART (Bruker, 2000), SAINT-Plus (Bruker, 2001), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg & Putz, 2006), publCIF (Westrip, 2010).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3···N1ⁱ	0.93	2.54	3.412 (5)	157
C1—Cl1···N2ⁱⁱ	1.713 (4)	3.241 (4)	4.820 (5)	151.9 (2)
C5—Cl2···N3ⁱⁱⁱ	1.717 (4)	3.281 (5)	4.851 (6)	150.6 (2)

Symmetry codes: (i) −x+3/2, y−1/2, z; (ii) −x+5/2, y+1/2, z; (iii) −x+1/2, y+1/2, z.

Acknowledgements

This work was supported by the National University Research Council of Romania (CNCSIS–UEFISCSU); project number PNII–IDEI 570/2007. We thank Dr Ciprian Rat for helpful disussions and advice.

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