2-[2,6-Bis(pyrazin-2-yl)pyridin-4-yl]benzoic acid

Ying Shuai; Xiang-Yang Wang; Jing-Wei Dai; Jian-Zhong Wu

doi:10.1107/S1600536814008496

. 2014 Apr 18;70(Pt 5):o577–o578. doi: 10.1107/S1600536814008496

2-[2,6-Bis(pyrazin-2-yl)pyridin-4-yl]benzoic acid

Ying Shuai ^a, Xiang-Yang Wang ^a, Jing-Wei Dai ^a, Jian-Zhong Wu ^a,^*

PMCID: PMC4011275 PMID: 24860380

Abstract

In the title compound, C₂₀H₁₃N₅O₂, the two pyrazine rings are nearly coplanar with the central pyridine ring, forming dihedral angles of 2.21 (9) and 4.57 (9)°. In contrast, the strong steric hindrance caused by the ortho-carboxyl group on the phenyl ring makes this ring rotate out of the attached pyridine ring plane by 52.60 (9)°. The carboxyl group is twisted from the phenyl ring by 22.6 (1)°. In the crystal, aromatic π–π stacking interactions [centroid–centroid distances = 3.9186 (4) and 3.9794 (5) Å] occur between the antiparallel molecules, generating infinite chains along [100]. O—H⋯O hydrogen bonds connect the chains, leading to the formation of a two-dimensional supramolecular network parallel to (010). Intermolecular C—H⋯N hydrogen bonds are also observed.

Related literature

For background to terpyridine compounds, see: Constable (2008 ▶); Eryazici et al. (2008 ▶); Schubert et al. (2006 ▶); Wild et al. (2011 ▶); Zadykowicz & Potvin (1999 ▶); Wang & Hanan (2005 ▶). For similar dipyrazinylpyridine compounds, see: Dares et al. (2011 ▶); Dai et al. (2010a ▶,b ▶); Vougioukalakis et al. (2010 ▶); Liegghio et al. (2001 ▶).

Experimental

Crystal data

C₂₀H₁₃N₅O₂
M _r = 355.35
Triclinic,
a = 7.0253 (9) Å
b = 10.9070 (14) Å
c = 11.3218 (14) Å
α = 99.345 (2)°
β = 99.266 (2)°
γ = 102.513 (2)°
V = 818.17 (18) Å³
Z = 2
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 298 K
0.22 × 0.16 × 0.15 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2002 ▶) T _min = 0.979, T _max = 0.985
4395 measured reflections
2998 independent reflections
1732 reflections with I > 2σ(I)
R _int = 0.022

Refinement

R[F ² > 2σ(F ²)] = 0.049
wR(F ²) = 0.137
S = 1.00
2998 reflections
244 parameters
H-atom parameters constrained
Δρ_max = 0.16 e Å⁻³
Δρ_min = −0.17 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: SAINT (Bruker, 2004 ▶); data reduction: SAINT; 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, 2012 ▶); software used to prepare material for publication: PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536814008496/mw2121sup1.cif

e-70-0o577-sup1.cif^{(171.8KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536814008496/mw2121Isup2.hkl

e-70-0o577-Isup2.hkl^{(164.6KB, hkl)}

Click here for additional data file.^{(4.2KB, cdx)}

Supporting information file. DOI: 10.1107/S1600536814008496/mw2121Isup3.cdx

Click here for additional data file.^{(6.7KB, cml)}

Supporting information file. DOI: 10.1107/S1600536814008496/mw2121Isup4.cml

CCDC reference: 997338

Additional supporting information: crystallographic information; 3D view; checkCIF report

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1A⋯O2ⁱ	0.82	1.84	2.656 (3)	176
C15—H15⋯N2ⁱⁱ	0.93	2.56	3.438 (3)	157

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Symmetry codes: (i) Inline graphic ; (ii) .

Acknowledgments

Financial support from the South China Normal University is gratefully acknowledged.

supplementary crystallographic information

1. Comment

Terpyridine compounds are among the most frequently used tridentate ligands for transition metal elements (Constable, 2008; Eryazici et al., 2008; Schubert et al., 2006; Wild et al.). However, the similar dipyrazinylpyridine compounds have received much less attention and only a few structures have been reported (Dares et al., 2011; Dai et al., 2010a; Dai et al., 2010b; Vougioukalakis et al., 2010; Liegghio et al., 2001). We previously demonstrated that 4-p-tolyl-2,6-di(pyrazin-2-yl)pyridine has stronger intermolecular interactions than its isoelectronic counterpart 4-p-tolyl-2,2':6',2''-terpyridine (suggested by a 90°C higher melting point for the former) and their coordination behaviours are also somewhat different (Dai et al., 2010a). Herein we report the synthesis of 4-o-carboxyphenyl-2,6-di(pyrazin-2-yl)pyridine, (I), the first carboxyl-containing dipyrazinylpyridine compound, via by the Kröhnke reaction in a very convenient one-pot method in quantitative yield which contrasts with the frequently used two-step procedures for preparation of many terpyridine compounds (Schubert et al., 2006). The molecular structure of (I) is shown in Fig. 1. Both pyrazinyl rings have their ortho N-atoms anti to the central pyridyl N atom. This conformation is free of possible steric strain between the vicinal C–H groups of the central pyridyl and the peripheral pyrazinyl rings and also avoids the lone-pair repulsions between syn-- positioned N atoms (Zadykowicz & Potvin, 1999) as is commonly found for the non-coordinated terpyridine or dipyrazinylpyridine compounds (Dares et al., 2011; Dai et al., 2010b; Vougioukalakis et al., 2010; Liegghio et al., 2001). The two pyrazinyl rings are nearly coplanar with the pyridyl ring as the dihedral angles between the N3- and N5-containing pyrazinyl rings and the pyridyl ring are 2.21 (9)° and 4.57 (9)°, respectively. In contrast, the strong steric hindrance caused by the ortho-carboxyl group on the phenyl ring makes this ring rotate out of the attached pyridyl plane by 52.60 (9)°. The carboxyl group twists from the phenyl ring by 22.6 (1)°.

The O–H···O and C–H···N hydrogen bonds (Table 1) as well as the aromatic π–π stacking interactions direct the crystal packing. As displayed in Fig. 2, each planar dipyrazinylpyridine moiety is antiparallel to two other moieties above and below it generating π–π stacking interactions as evidenced by the centroid-centroid distances between the nearly parallel aromatic rings: Cg(N2/N3/C1–C4)···Cg(N1/C5–C9)ⁱ 3.9186 (4) Å and Cg(N2/N3/C1–C4)···Cg(N1/C5–C9)ⁱⁱ 3.9794 (5) Å [symmetry codes: (i) –x, –y, –z+1; (ii) x+1, y, z]. The presence of a C15–H15···N2ⁱ hydrogen bond (Table 1, Fig. 2) may account for the fact that the former centroid-centroid distance is a little shorter than the latter. The continuous stacking of the pyridyl and the N2-containing pyrazinyl rings leads to formation of infinite one-dimensional chains along the (100) direction. Between the neighbouring chains there are strong O1–H1A···O2ⁱⁱⁱ [(iii) –x+1, –y, –z] hydrogen bonds (Table 1, Fig. 2) forming a two-dimensional supramolecular network parallel to (010). There are no significant interactions among these sheets.

2. Experimental

To 15 mL of a methanolic solution of 2-acetylpyrazine (0.813 g, 6.7 mmol) and 2-carboxybenzaldehyde (0.5 g, 3.3 mmol) was added 10 mL of an aqueous solution of potassium hydroxide (3.57 mol·L^–1) and then 15 mL of concentrated ammonia. After stirring for 24 h, the solution was acidified to pH 3–4 using hydrochloric acid. The resulting yellow precipitate was collected and washed with water and ethanol (yield 97%). Yellow crystals were obtained by recrystallization from chloroform, m.p. 282.2–284.0°C. IR (υ/cm^–1): 3134, 3047, 1717, 1604, 1470, 1374, 1250, 1119, 1015, 850, 760, 690, 626, 480; ¹H NMR (400 MHz, CDCl_3, TMS, δ/ppm): 9.83 (s, 2H, pyrazinyl NCHCN), 8.61 (m, 4H, pyrazinyl NCHCHN), 8.46 (s, 2H, pyridyl NCCH), 8.06 (d, 1H, phenyl CHCCOOH), 7.59 (t, 1H, phenyl CHCHCHCCOOH), 7.51 (t, 1H, phenyl CHCHCHCHCCOOH), 7.43 (d, 1H, phenyl CHCHCCOOH); ESI-MS: m/z = 354 ([M–H]^–).