Conformational stability, barriers to internal rotation, vibrational assignment, and a b i n i t i o calculations of chloroacetyl fluoride
- 1 August 1988
- journal article
- research article
- Published by AIP Publishing in The Journal of Chemical Physics
- Vol. 89 (3) , 1285-1296
- https://doi.org/10.1063/1.455718
Abstract
The far infrared spectrum of gaseous chloroacetyl fluoride, CH2ClC(O)F, has been recorded at a resolution of 0.10 cm−1 in the 350 to 35 cm−1 region. The fundamental asymmetric torsional frequencies of the more stable trans (two halogen atoms oriented trans to one another) and high energy gauche (Cl–C–C=O torsional dihedral angle of 122°) have been observed at 86.5 and 48.8 cm−1, respectively, each with excited states falling to lower frequency. From these data the asymmetric torsional potential function governing internal rotation about the C–C bond has been determined. This potential function is consistent with torsional potential coefficients of: V1=350±12, V2=306±6, V3=420±1, V4=44±1, and V6=2±1 cm−1. The trans to gauche, gauche to gauche, and gauche to trans barriers have been determined to be 796, 245, and 271 cm−1, respectively, with an energy difference between the conformations of 525±24 cm−1 (1.50±0.07 kcal/mol). From studies of the Raman spectrum at variable temperatures the conformational energy difference has been determined to be 445±80 (1.27±0.2 kcal/mol) and 534±68 cm−1 (1.53±0.2 kcal/mol) for the gaseous and liquid phases, respectively. A complete assignment of the vibrational fundamentals observed from the infrared (3500 to 50 cm−1) spectra of the gaseous and solid states and Raman (3200 to 10 cm−1) spectra of the gaseous, liquid, and solid states is proposed. All of these data are compared to the corresponding quantities obtained from ab initio Hartree–Fock gradient calculations employing both the 3‐21G* and 6‐31G* basis sets. Additionally, complete equilibrium geometries have been determined for both rotamers. The results are discussed and compared with the corresponding quantities obtained for some similar molecules.Keywords
This publication has 11 references indexed in Scilit:
- Microwave spectra of chloro, bromo, and hydroxy derivatives of acetyl fluorideJournal of Molecular Spectroscopy, 1985
- Molecular structure and conformation of gaseous chloroacetyl chloride as determined by electron diffractionJournal of Molecular Structure, 1980
- Microwave spectra and molecular structures of rotational isomers of fluoroacetic acid and fluoroacetyl fluorideJournal of Molecular Structure, 1978
- Microwave spectrum of fluoroacetyl chlorideJournal of Molecular Spectroscopy, 1974
- Determination of the Gauche Dihedral Angle and the Energy Difference between Rotational Isomers of Bromoacetyl ChlorideBulletin of the Chemical Society of Japan, 1974
- Determination of energy differences between rotational isomers of chloroacetyl chloride, bromoacetyl bromide and dichloroacetyl chloride by the absolute infrared intensity methodSpectrochimica Acta Part A: Molecular Spectroscopy, 1972
- Rotational Isomerism in Fluoroacetyl HalidesThe Journal of Chemical Physics, 1970
- Rotational Isomerism in Chloroacetyl HalidesThe Journal of Chemical Physics, 1969
- Study of Rotational Isomerism in Fluoroacetyl Fluoride by Microwave SpectroscopyThe Journal of Chemical Physics, 1967
- Rotational Isomers of Chloroacetyl Chloride, Bromoacetyl Chloride, and Bromoacetyl BromideThe Journal of Chemical Physics, 1952