6-Chloronicotinic acid

Abstract

The title compound, C6H4ClNO2, forms centrosymmetric dimers via inter­molecular hydrogen bonds between carboxylic groups. Weak Cl⋯Cl inter­actions further bridge these dimers, leading to infinite chains. In contrast, acid‐to‐pyridine hydrogen‐bonded catemer motifs are observed in both nicotinic acid and 2‐chloro­nicotinic acid. Only intra­molecular halogen‐bonded S(5) loops exist in 2‐chloro­nicotinic acid.

Experimental vibrational spectra (Raman, infrared) and DFT calculations on monomeric and dimeric structures of 2‐ and 6‐bromonicotinic acid

“…The available experimental geometric parameters for similar compounds are also listed for comparison. [10,11] As mentioned above, the results for the most stable conformer and the structures upon dimerization have been tabulated. Intermolecular hydrogen bonds can be responsible for the geometry and the stability of a predominant conformation; the intermolecular O-H· · ·N hydrogen bond between the pyridine N atom-carboxylic acid OH group, and the formation of hydrogen bonding between a hydroxyl group O COH, cause the structure of the conformer C1 to be the most stable for 2-BrNA and 6-BrNA.…”

“…Since the experimental geometries of free 2/6-BrNA are not available, the spatial coordinate positions of 2/6-chloronicotinic acid, as obtained from an X-ray structural analysis, [10,11] were used as the initial coordinates for the theoretical calculations. The hybrid B3LYP method [12,13] based on Becke's three-parameter functional of DFT and 6-311G++(d,p) basis set level were chosen.…”

Tetraaquabis(6-chloropyridine-3-carboxylato-κO)nickel(II) tetrahydrate

“…For background to complexes based on 6-chloronicotinic acid, see: Long et al (2007); Li et al (2006).…”

The crystal structure of 5-bromo-2-fluoronicotinic acid monohydrate, C6H5BrFNO3

“…There is an one-dimensional water molecular chain constructed by hydrogen bond O1W-H1WA• • • O1W, which are linked by hydrogen bonds O1-H1• • • O1W and O1W-H1WB• • • N1 to generate a three-dimensional supramolecular structure. All the bond lengths are similar to their analogues [6][7][8][9][10].…”

“…To date, some single-crystal stuctures of mono-or multihalogen-substituted nicotinic acids (although called pyridine-3-carboxylic acid) have been reported, including 6-fluoronicotinic acid [5], 2-chloro-pyridine-3-carboxylic acid [6], 2-chloro-6-(trifluoromethoxy)nicotinic acid and 6-chloro-2-(trifluoromethoxy)nicotinic acid [7], 6-chloronicotinic acid [8], 2-bromo-pyridine-3-carboxylic acid [9], and 5-bromonicotinic acid [10]. However, to the best of our knowledge, the single-crystal stucture of a mixed halogen-substituted nicotinic acid has not been reported.…”