title: Structural, vibrational and quantum chemical investigations on 5-chloro-2-hydroxybenzamide and 5-chloro-2-hydroxybenzoic acid.
abstract: The Fourier transform infrared (FTIR) and FT-Raman spectra of 5-chloro-2-hydroxybenzamide (5CBA) and 5-chloro-2-hydroxybenzoic acid (5C2HBA) have been recorded in the range 4000-400 and 4000-100 cm(-1), respectively. The complete vibrational fundamental modes of the compounds were assigned and analysed using the observed FTIR and FT-Raman data. The vibrational frequencies determined experimentally were compared with the theoretical wavenumbers calculated from ab initio HF and DFT-B3LYP gradient methods employing 6-31G** and 6-311++G** basis sets. The effect of halogen, hydroxyl groups and hydrogen bonding on the characteristic frequencies of the -COOH and -CONH2 group frequencies have been investigated. In 5CBA and 5C2HBA intramolecular hydrogen bond between a hydroxyl group and CO group makes a six membered ring, which causes the O⋯H interaction onto the resonance of the benzene ring. Comparison of the positions of the ν(OH) bands shows the ν(OH) band of 5CBA is located at considerably higher frequency which confirms a weaker hydrogen bond than in 5C2HBA.
authors.affiliation: Department of Chemistry, Kanchi Mamunivar Centre for Post-Graduate Studies, Puducherry 605 008, India. varjunftir@yahoo.com
authors.forename: V
authors.initials: V
authors.lastname: Arjunan
authors.forename: M
authors.initials: M
authors.lastname: Kalaivani
authors.forename: P
authors.initials: P
authors.lastname: Ravindran
authors.forename: S
authors.initials: S
authors.lastname: Mohan
mesh_terms: D001549:Benzamides / Q000737:chemistry*; D002722:Chlorobenzenes; D006860:Hydrogen Bonding; D062385:Hydroxybenzoates / Q000737:chemistry*; D015394:Molecular Structure; D011789:Quantum Theory; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D014732:Vibration
chemical_list: C524082:2-hydroxybenzamide; C568213:5-chloro-2-hydroxybenzamide; C568217:5-chloro-2-hydroxybenzoic acid; D001549:Benzamides; D002722:Chlorobenzenes; D062385:Hydroxybenzoates