5,6-Diphenyl­pyrazine-2,3-dicarbonitrile

Tuncer Hökelek; Ergin Yalçın; Zeynel Seferoğlu; Ertan Şahin

doi:10.1107/S1600536809033029

. 2009 Aug 22;65(Pt 9):o2225. doi: 10.1107/S1600536809033029

5,6-Diphenylpyrazine-2,3-dicarbonitrile

Tuncer Hökelek ^a,^*, Ergin Yalçın ^b, Zeynel Seferoğlu ^b, Ertan Şahin ^c

PMCID: PMC2970004 PMID: 21577624

Abstract

In the title compound, C₁₈H₁₀N₄, the pyrazine ring is oriented at dihedral angles of 48.08 (7) and 44.80 (7)° with respect to the phenyl rings, while the dihedral angle between the phenyl rings is 49.47 (7)°. In the crystal structure, weak π–π contacts between pyrazine and phenyl rings [centroid–centroid distance = 3.813 (1) Å] may stabilize the structure.

Related literature

For applications of 2,3-dicyanopyrazine derivatives, see: Hou et al. (1993 ▶); Jaung et al. (1996 ▶); Takematsu et al. (1981 ▶). For a related structure, see: Zhang et al. (2009 ▶). For bond-length data, see: Allen et al. (1987 ▶).

Experimental

Crystal data

C₁₈H₁₀N₄
M _r = 282.31
Monoclinic,
a = 9.2195 (2) Å
b = 7.2837 (2) Å
c = 21.5507 (5) Å
β = 101.108 (1)°
V = 1420.06 (6) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 294 K
0.30 × 0.15 × 0.10 mm

Data collection

Rigaku R-AXIS RAPID-S diffractometer
Absorption correction: none
28933 measured reflections
2911 independent reflections
1708 reflections with I > 2σ(I)
R _int = 0.137

Refinement

R[F ² > 2σ(F ²)] = 0.057
wR(F ²) = 0.145
S = 1.05
2911 reflections
200 parameters
H-atom parameters constrained
Δρ_max = 0.14 e Å⁻³
Δρ_min = −0.18 e Å⁻³

Data collection: CrystalClear (Rigaku/MSC, 2005 ▶); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶) and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809033029/xu2592sup1.cif

e-65-o2225-sup1.cif^{(17.6KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809033029/xu2592Isup2.hkl

e-65-o2225-Isup2.hkl^{(140KB, hkl)}

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

Acknowledgments

The authors are indebted to the Department of Chemistry, Atatürk University, Erzurum, Turkey, for the use of X-ray diffractometer purchased under grant No. 2003/219 of the University Research Fund.

supplementary crystallographic information

Comment

2,3-Dicyanopyrazine derivatives have become a potential subject of investigation because of their wide variety of applications, which include heterocycles for bioactive substances, coloring matters, nonlinear optical (NLO) and electroluminescence (EL) materials (Hou et al., 1993; Jaung et al., 1996). They are also the intermediate compounds to synthesize phthalocyanine dyes, which is nowadays a very important class of dyes. On the other hand, it has been found that a group of 2,3-dicyanopyrazine derivatives have very good herbicidial activity in treatment of the soil of water-submerged paddies, foliage of weeds in the growth period, and the soil of upland farms, these compounds generally tend to form a rigid chemical-treated layer in the surface of the soil, and have the ability to control barnyard grass and other annual and perennial weeds excellently with substantially no phytotoxicity to transplanted rise plants (Takematsu et al., 1981). The present study was undertaken in order to ascertain the crystal structure of the title compound.

In the molecule of the title compound, (Fig. 1), the bond lengths (Allen et al., 1987) and angles are within normal ranges. The cyano groups bond lengths C17—N4 [1.138 (3) Å] and C18—N3 [1.138 (3) Å] are in good agreement with the corresponding values [1.140 (2) and 1.142 (2) Å] reported in 4,5-diaminobenzene-1,2-dicarbonitrile (Zhang et al., 2009). Rings A (C1—C6), B (C7—C12) and C (N1/N2/C13—C16) are, of course, planar and they are oriented at dihedral angles of A/B = 49.47 (7), A/C = 48.08 (7) and B/C = 44.80 (7)°.

In the crystal structure, the π–π contact between the pyrazine and the phenyl rings, Cg1—Cg2ⁱ, [symmetry code: (i) 1/2 - x, 1/2 + y, 1/2 - z, where Cg1 and Cg2 are centroids of the rings C (N1/N2/C13—C16) and A (C1—C6), respectively] may stabilize the structure, with centroid-centroid distance of 3.813 (1) Å.

As can be seen from the packing diagram (Fig. 2), the molecules are stacked along the b axis and elongated along the a axis.

Experimental

For the preparation of the title compound, a mixture of benzyl (2.10 g, 10 mmol), diaminomaleonitrile (1.18 g, 11 mmol) and acetic acid (2 ml) in ethanol (20 ml) and water (15 ml) was heated at 348 K overnight. The reaction mixture was cooled, and water (20 ml) was added. The precipitate was filtered and washed with ethanol and then ether. The crude product was dissolved in dichloromethane and treated with activated charcoal. The solid was recrystallized from ethanol to give colorless crystals (yield; 1.97 g, 70%, m.p. 516–518 K).