3-Fluoro­benzoic acid–4-acetyl­pyridine (1/1) at 100 K

Gavin A Craig; Lynne H Thomas; Martin S Adam; Angela Ballantyne; Andrew Cairns; Stephen C Cairns; Gary Copeland; Clifford Harris; Eve McCalmont; Robert McTaggart; Alan R G Martin; Sarah Palmer; Jenna Quail; Harriet Saxby; Duncan J Sneddon; Graeme Stewart; Neil Thomson; Alex Whyte; Chick C Wilson; Andrew Parkin

doi:10.1107/S1600536809002396

. 2009 Jan 23;65(Pt 2):o380. doi: 10.1107/S1600536809002396

3-Fluorobenzoic acid–4-acetylpyridine (1/1) at 100 K

Gavin A Craig ^a, Lynne H Thomas ^a,^*, Martin S Adam ^a, Angela Ballantyne ^b, Andrew Cairns ^b, Stephen C Cairns ^a, Gary Copeland ^b, Clifford Harris ^b, Eve McCalmont ^b, Robert McTaggart ^b, Alan R G Martin ^b, Sarah Palmer ^b, Jenna Quail ^b, Harriet Saxby ^b, Duncan J Sneddon ^a, Graeme Stewart ^b, Neil Thomson ^b, Alex Whyte ^b, Chick C Wilson ^a, Andrew Parkin ^a

PMCID: PMC2968409 PMID: 21581976

Abstract

In the title compound, C₇H₅FO₂·C₇H₇NO, a moderate-strength hydrogen bond is formed between the carboxyl group of one molecule and the pyridine N atom of the other. The benzoic acid molecule is observed to be disordered over two positions with the second orientation only 4% occupied. This disorder is also reflected in the presence of diffuse scattering in the diffraction pattern.

Related literature

For the structure of pure m-fluorobenzoic acid, see: Taga et al. (1985 ▶). For standard bond-length data, see: Allen et al. (1992 ▶).

Experimental

Crystal data

C₇H₅FO₂·C₇H₇NO
M _r = 261.25
Monoclinic,
a = 10.0498 (11) Å
b = 10.5779 (8) Å
c = 11.5045 (8) Å
β = 92.026 (4)°
V = 1222.23 (18) Å³
Z = 4
Mo Kα radiation
μ = 0.11 mm⁻¹
T = 100 (2) K
0.3 × 0.25 × 0.2 mm

Data collection

Rigaku R-AXIS RAPID IP image-plate diffractometer
Absorption correction: none
15130 measured reflections
2787 independent reflections
1888 reflections with I > 2σ(I)
R _int = 0.031

Refinement

R[F ² > 2σ(F ²)] = 0.035
wR(F ²) = 0.099
S = 1.05
2787 reflections
220 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.23 e Å⁻³
Δρ_min = −0.21 e Å⁻³

Data collection: CrystalClear (Rigaku, 2008 ▶); 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 (Farrugia, 1997 ▶) and Mercury (Macrae et al., 2006 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809002396/lh2755sup1.cif

e-65-0o380-sup1.cif^{(18.1KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809002396/lh2755Isup2.hkl

e-65-0o380-Isup2.hkl^{(166.7KB, 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
O9—H9⋯N11	0.97 (2)	1.68 (2)	2.6428 (14)	176.3 (18)
C19—H19C⋯O10ⁱ	0.96 (2)	2.57 (2)	3.385 (2)	142.5 (14)
C13—H13⋯F1ⁱⁱ	0.98 (2)	2.63 (2)	3.3870 (16)	134.3 (12)

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

Acknowledgments

The authors thank Rigaku for the loan of the diffractometer.

supplementary crystallographic information

Comment

The structure of a molecular complex of 3-fluorobenzoic acid with 4-acetylpyridine (C₇H₅O₂F C₇H₇NO) at 100 K is reported (Fig. 1). The molecular geometry of the 4-acetylpyridine is generally unremarkable. However the F atom in the 3-fluorobenzoic acid molecule is seen to be disordered over two positions in a 96:4% ratio. The majority component is found to lie on the same side of the molecule as the carbonyl C═O and this is consistent with the reported crystal structure of the pure material (Taga et al., 1985). The minority component was identified using a Fourier difference map which shows a peak height of greater than 1 electron bonded to C6, at a distance longer than characteristic for a C—H bond. The inclusion of a disorder model even at the 4% level improves the model significantly. Diffuse scattering was also observed in the diffraction images supporting the presence of disorder in this material. The minor component F atom was modelled isotropically and with constraints on the C—F distance. The thermal ellipsoids of both the carboxylic acid group and the methyl-keto group are slightly larger than those of their corresponding aromatic rings, indicating the possible presence of a small amount of libration in these groups.

A moderate strength hydrogen bond [O···N = 2.6428 (14) Å] is formed between the carboxylic acid group and the pyridine N atom. There is no indication of disorder of the carboxylic H atom at this temperature although the H atom isotropic thermal parameter is large as is often observed in the presence of a hydrogen bond. The two molecules lie almost exactly co-planar with each other.

These dimers are packed in an offset planar arrangement, as shown in Figs. 2 and 3. All the molecules are approximately co-planar with the (103) plane. The reason that this offset occurs may be due to the optimization of two close contacts from the methyl group. These contacts comprise a C—H···O interaction between the methyl group of the 4-acetylpyridine and the C═O of the carboxylic acid between planes, which induces an attractive tilt upwards in the acetylpyridine towards this acid molecule. Equally, the C—H···F interaction within the plane causes an attractive tilt in the adjacent molecule, giving rise to this offset packing arrangement.

Experimental

Crystals of the title material were grown by slow evaporation of solvent from a 1:1 solution of the two component molecules in ethanol.