Ab initio calculations on 2-fluoroethanol and 2-chloroethanol with reference to the infrared photorotamerization processes in low-temperature matrices
| Autor: | Leila Homanen, Juhani Murto, Markku Raspanen, Antero Aspiala |
|---|---|
| Rok vydání: | 1983 |
| Předmět: |
Infrared
2-Fluoroethanol Organic Chemistry Ab initio Infrared spectroscopy Analytical Chemistry Inorganic Chemistry chemistry.chemical_compound chemistry Computational chemistry Ab initio quantum chemistry methods Saddle point Intramolecular force Physical chemistry Conformational isomerism Spectroscopy |
| Zdroj: | Journal of Molecular Structure. 92:45-56 |
| ISSN: | 0022-2860 |
| DOI: | 10.1016/0022-2860(83)90349-6 |
| Popis: | Ab initio STO-3G optimizations have been carried out on the five conformers of 2fluoro- and 2-chloro-ethanol and on ten saddle point conformations of 2-fluoroethanol. The relative order of the calculated conformer energies is found to be Gg′ ⪡ Tt −1 , respectively. Large variations (4–7°) are found for the angles CCO and OCH from conformer to conformer and a general angle rule is presented for primary alcohols. Neglect of this effect is the main source of error in rigid-rotation calculations on alcohols (as compared with fully optimized calculations), of the order of 5 kJ mol −1 . The use of calculated OH stretching force constants in assigning νOH band fine structure in IR spectra is discussed. Evidence for a weak intramolecular hydrogen-bonding interaction is found, especially in the case of 2-chloroethanol. On the basis of calculated conformer energies, barriers to rotation and force constants it is deduced that for both of these alcohols the photorotamerization process in matrices is either Gg′ → Tt or Gg′ → Gt. |
| Databáze: | OpenAIRE |
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