2,3-Difluoro-N-(2-pyrid­yl)benzamide

John F Gallagher; Joyce McMahon; Frankie P Anderson; Alan J Lough

doi:10.1107/S1600536808038269

. 2008 Nov 20;64(Pt 12):o2394. doi: 10.1107/S1600536808038269

2,3-Difluoro-N-(2-pyridyl)benzamide

John F Gallagher ^a,^*, Joyce McMahon ^a, Frankie P Anderson ^b, Alan J Lough ^c,^‡

PMCID: PMC2959868 PMID: 21581364

Abstract

The title compound, C₁₂H₈F₂N₂O, crystallizes with two independent molecules in the asymmetric unit. The independent molecules differ slightly in conformation; the dihedral angles between the benzene and pyridine rings are 51.58 (5) and 49.97 (4)°. In the crystal structure, molecules aggregate via N—H⋯N_pyridine interactions as hydrogen-bonded dimers with the structural motif R ₂ ²(8), and these dimers are linked via C—H⋯O interactions to form a supramolecular chain.

Related literature

For background information, see: Chopra & Row (2008 ▶); Donnelly et al. (2008 ▶); Gelbrich et al. (2007 ▶); McMahon et al. (2008 ▶). For a related structure, see: Forbes et al. (2001 ▶). For the Cambridge Structural Database, see: Allen (2002 ▶).

Experimental

Crystal data

C₁₂H₈F₂N₂O
M _r = 234.20
Monoclinic,
a = 11.8515 (4) Å
b = 9.0554 (2) Å
c = 20.1075 (7) Å
β = 100.2620 (15)°
V = 2123.42 (11) Å³
Z = 8
Mo Kα radiation
μ = 0.12 mm⁻¹
T = 150 (1) K
0.26 × 0.20 × 0.15 mm

Data collection

Nonius KappaCCD diffractometer
Absorption correction: multi-scan (SORTAV; Blessing, 1995 ▶) T _min = 0.875, T _max = 0.981
5113 measured reflections
4803 independent reflections
3170 reflections with I > 2σ(I)
R _int = 0.045

Refinement

R[F ² > 2σ(F ²)] = 0.046
wR(F ²) = 0.128
S = 1.04
4803 reflections
316 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.22 e Å⁻³
Δρ_min = −0.23 e Å⁻³

Data collection: KappaCCD Server Software (Nonius, 1997 ▶); cell refinement: DENZO–SMN (Otwinowski & Minor, 1997 ▶); data reduction: DENZO–SMN; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶) and SORTX (McArdle, 1995 ▶); molecular graphics: PLATON (Spek, 2003 ▶); software used to prepare material for publication: SHELXL97 and PREP8 (Ferguson, 1998 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808038269/tk2329sup1.cif

e-64-o2394-sup1.cif^{(22.4KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808038269/tk2329Isup2.hkl

e-64-o2394-Isup2.hkl^{(235.3KB, hkl)}

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
N1A—H1A⋯N22B	0.894 (19)	2.076 (19)	2.968 (2)	175.9 (16)
N1B—H1B⋯N22A	0.90 (2)	2.10 (2)	2.999 (2)	175.4 (17)
C25B—H25B⋯O1Aⁱ	0.95	2.48	3.379 (2)	159
C25A—H25A⋯O1Bⁱⁱ	0.95	2.67	3.542 (2)	153

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

Acknowledgments

JFG thanks Dublin City University for the grants in aid of undergraduate research. Thanks especially to Mr Damien McGuirk for providing excellent technical assistance in the undergraduate research laboratories.

supplementary crystallographic information

Comment

Our group is completing a structural systematic study of fluoro-N'-(pyridyl)benzamide isomers (Donnelly et al., 2008) and are adding to our research with the analogous difluoro-N-(pyridyl)benzamide series (McMahon et al., 2008) (Scheme 1). A total of 18 isomers are possible via amide formation and resulting through condensation of the 2,3-, 2,4-, 2,5-, 2,6-, 3,4-, 3,5-difluorobenzoyl chlorides with the 4-/3-/2-aminopyridines. The 2,3-, 2,4- and 2,5-difluoro-N-(4-pyridyl)benzamides have already been reported by us (McMahon et al., 2008). Systematic structural analyses have recently been reported for related fluoro derivatives (Chopra & Row, 2008) and isomeric series (Gelbrich et al., 2007).

There is a dearth of structural information in the literature on all six possible difluorobenzene derivatives F₂C₆H₃—Z (Z = remainder of molecule) from analysis of structural data in the Cambridge Structural Database (Allen 2002; v5.29, Nov 2007 issue + 2 updates). In this structural report the structure of 2,3-difluoro-N-(2-pyridyl)benzamide (I), Fig. 1, is described.

Compound (I) crystallizes with two molecules, A and B (which differ slightly in conformation) in the asymmetric unit: the C₆/C₅N internal angles are 51.58 (5)° and 49.97 (4)°, respectively, see overlay diagram, Fig. 2. Molecules aggregate via N—H···N interactions as hydrogen bonded dimers with structural motif R₂²(8); see Table 1 for geometric parameters. The [N1A/C21A/N22A/H1A] and [N1B/C21B/N22B/H1B] interplanar angle is 36.2 (3)° and deviates considerably from co-planarity therefore highlighting a degree of twist between the two interacting molecules. Hydrogen bonded dimers are linked into a supramolecular chain via C—H···O=C intermolecular interactions, Table 1 and Fig. 3.

An analysis of the Cambridge Structural Database reveals a related structure pentafluoro-N-(2-pyridyl)benzamide (II) [CSD code IDALAA] (Forbes et al., 2001) where molecules also form hydrogen bonded dimers in space group P1 (No. 2) with Z'=2. The N···N intermolecular distances in (II) are 2.9568 (14) and 3.0734 (15) Å.

Experimental

Compound (I) was synthesized via standard condensation procedures and similar to the related syntheses reported previously (Donnelly et al., 2008; McMahon et al., 2008).

Typical organic workup and washing gave the product (I) in modest yield of 15–20%. Crystals suitable for diffraction were grown from CHCl₃ solution as colourless blocks over a period of 1–2 weeks. The compounds gave clean ¹H and ¹³C NMR spectra in δ₆-DMSO and infrared spectra (in CHCl₃ solution, and as KBr disks).

For (I), m.p. 348–352 K (uncorrected). IR (ν_C=O cm^-1): 1644(s), (CHCl₃); 1695(s) (KBr). ¹H NMR (400 MHz, DMSO): δ 11.02 (s, 1H, N—H), 8.38 (d, 1H), 8.18 (d, 1H), 7.87 (t, 1H), 7.61 (q, 1H), 7.50 (t, 1H), 7.34 (q, 1H), 7.19 (t, 1H).