2-(2,4-Difluoro­phen­yl)-5-nitro­pyridine

Feng Sun; Xuan Shen; Rui Zhao; Xin Wang; Dun-Ru Zhu

doi:10.1107/S1600536812024713

. 2012 Jun 2;68(Pt 7):o2001. doi: 10.1107/S1600536812024713

2-(2,4-Difluorophenyl)-5-nitropyridine

Feng Sun ^a, Xuan Shen ^a,^*, Rui Zhao ^a, Xin Wang ^a, Dun-Ru Zhu ^a,^*

PMCID: PMC3393273 PMID: 22807830

Abstract

In the title molecule, C₁₁H₆F₂N₂O₂, the benzene and pyridine rings form a dihedral angle of 32.57 (6)°. The nitro group is tilted with respect to the pyridine ring by 12.26 (9)°. An intramolecular C—H⋯F hydrogen bond is present. In the crystal, molecules interact through π–π stacking interactions [centroid–centroid distances = 3.7457 (14) Å], forming columnar arrangements along the b axis. The crystal packing is further enforced by intermolecular C—H⋯O and C—H⋯N hydrogen bonds.

Related literature

For general background to organic light-emitting diodes (OLEDs), see: Baldo et al. (2000 ▶); Flamigni et al. (2007 ▶); Yang et al. (2007 ▶); Yersin (2008 ▶). For luminescent Ir^III complexes containing 2-phenylpyridine or its derivatives, see: Nazeeruddin et al. (2003 ▶); Dedeian et al. (2007 ▶); Chin et al. (2007 ▶); Shen et al. (2011 ▶).

Experimental

Crystal data

C₁₁H₆F₂N₂O₂
M _r = 236.18
Orthorhombic,
a = 22.185 (4) Å
b = 3.7457 (6) Å
c = 11.894 (2) Å
V = 988.4 (3) Å³
Z = 4
Mo Kα radiation
μ = 0.14 mm⁻¹
T = 296 K
0.14 × 0.12 × 0.08 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.981, T _max = 0.989
6331 measured reflections
1750 independent reflections
1450 reflections with I > 2σ(I)
R _int = 0.032

Refinement

R[F ² > 2σ(F ²)] = 0.034
wR(F ²) = 0.081
S = 1.06
1750 reflections
155 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.14 e Å⁻³
Δρ_min = −0.12 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT (Bruker, 2005 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812024713/rz2765sup1.cif

e-68-o2001-sup1.cif^{(15.4KB, cif)}

Supplementary material file. DOI: 10.1107/S1600536812024713/rz2765Isup2.mol

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812024713/rz2765Isup3.hkl

e-68-o2001-Isup3.hkl^{(86.2KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536812024713/rz2765Isup4.cml

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
C10—H10A⋯O1ⁱ	0.93	2.56	3.306 (3)	138
C8—H8A⋯N1ⁱⁱ	0.93	2.58	3.448 (3)	156
C4—H4A⋯F1	0.93	2.40	2.893 (3)	113

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

Acknowledgments

We are grateful to the Open Project Program of the State Key Laboratory of Materials-Oriented Chemical Engineering, China (grant No. KL10–14) and the National Natural Science Foundation of China (grant No. 21171093) for financial support.

supplementary crystallographic information

Comment

In recent years, Ir^III cyclometalated complexes have received considerable attention because of their outstanding photochemical and photophysical properties, which make this class of complexes widely suitable to a variety of photonic applications and promising emissive materials in organic light-emitting diodes (OLEDs) (Baldo et al., 2000; Flamigni et al., 2007; Yang et al., 2007; Yersin, 2008). Ir^III complexes containing 2-phenylpyridine (ppy) and its derivatives are known to exhibit high triplet quantum yields due to mixing the singlet and the triplet excited states via spin-orbit coupling, leading to high phosphorescence efficiencies (Nazeeruddin et al., 2003; Dedeian et al., 2007; Chin et al., 2007). It has been concluded that ppy-containing Ir^III complexes can emit lights covering a full range of visible colors by introducing electron-donating or -withdrawing groups to the pyridyl or phenyl rings, which can adjust the HOMO-LUMO energy gaps of the complexes (Shen et al., 2011). As a contribution to this research field, we report herein the synthesis and crystal structure of the title compound. The electron-withdrawing fluoro and nitro groups have been introduced on the phenyl and pyridine rings, respectively, of the title compound, and investigations on Ir^III complexes containing the title compound will be carried out soon.

The X-ray analysis of the title compound (Fig. 1) shows that the molecule is non-planar, the phenyl and pyridine rings forming a dihedral angle of 32.57 (6)°. The nitro group is slightly skewed with respect to the pyridine ring with a dihedral angle of 12.26 (9)%. An intramolecular C—H···F hydrogen bond (Table 1) stabilizes the molecular conformation. In the crystal structure (Fig. 2), π–π stacking interactions involving overlapping benzene and pyridine rings with centroid-to-centroid distances of 3.7457 (14) Å pack the molecules in columnar arrays running parallel the b axis. Furthermore, the columns interact via intermolecular C—H···O and C—H···N hydrogen bonds (Table 1).

Experimental

2-Chloro-5-nitropyridine (3.18 g, 20.0 mmol), 2,4-difluorophenylboric acid (4.00 g, 25.0 mmol) and triphenylphosphine (0.524 g, 2.0 mmol) were dissolved in THF (50 ml). After an aqueous solution of sodium carbonate (2 M, 30 ml) and palladium diacetate (0.122 g, 0.5 mmol) were added in, the mixture was refluxed under argon atmosphere for 24 h. After being cooled to room temperature, the reacted mixture was poured into water (50 ml) and was further extracted with dichloromethane (50 ml × 3). The combined extract was washed with saturated brine, dried over magnesium sulfate, and then evaporated to dryness. The crude product was purified by silica gel column chromatography (eluant: petroleum ether/ethyl acetate, 6:1 v/v), and colourless crystals of the title compound were at last obtained by recrystallization from ethanol in a yield of 70.5% (3.32 g).