Staggered and eclipsed conformations of C2F6

A systematic ab initio study

Rubén D. Parra, Xiao C Zeng

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Molecular geometries, energies, and vibrational frequencies for eclipsed and staggered conformers of perfluoroethane were determined by ab initio calculations. Basis set effects were investigated systematically with progressively larger basis sets, up to triple zeta, d and f polarization functions plus diffuse functions on all atoms. Electron correlation was included by means of Møller-Plesset perturbation calculations to the third order. Vibrational frequencies, calculated at both Hartree-Fock (HF) and second order Møller-Plesset perturbation (MP2) methods, were used to make zero-point energy and thermal corrections to electronic energies. Some semi-empirical methods and molecular mechanics force fields were also employed for comparison. The rotational barrier (3.81 kcal mol-1) predicted from the HF/6-311+G(3df) method is close to the measured electron diffraction value of 4.40 kcal mol-1 (-0.90,+1.10). The MP2/6-311G(d) level gives a lower barrier of 3.33 kcal mol-1, and the best MP3 calculation, MP3/6-311+G(3df)//MP2/6-311G(d), a value of 3.55 kcal mol-1.

Original languageEnglish (US)
Pages (from-to)51-60
Number of pages10
JournalJournal of Fluorine Chemistry
Volume83
Issue number1
DOIs
StatePublished - Jan 1 1997

Fingerprint

Conformations
Vibrational spectra
perturbation
Electrons
energy
Electron correlations
electron
Molecular mechanics
zero point energy
Mechanics
Electron diffraction
diffraction
field theory (physics)
mechanics
polarization
electron diffraction
Hot Temperature
Polarization
geometry
Atoms

Keywords

  • Ab initio
  • Perfluoroethane
  • Rotational barrier

ASJC Scopus subject areas

  • Biochemistry
  • Environmental Chemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

Cite this

Staggered and eclipsed conformations of C2F6 : A systematic ab initio study. / Parra, Rubén D.; Zeng, Xiao C.

In: Journal of Fluorine Chemistry, Vol. 83, No. 1, 01.01.1997, p. 51-60.

Research output: Contribution to journalArticle

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AB - Molecular geometries, energies, and vibrational frequencies for eclipsed and staggered conformers of perfluoroethane were determined by ab initio calculations. Basis set effects were investigated systematically with progressively larger basis sets, up to triple zeta, d and f polarization functions plus diffuse functions on all atoms. Electron correlation was included by means of Møller-Plesset perturbation calculations to the third order. Vibrational frequencies, calculated at both Hartree-Fock (HF) and second order Møller-Plesset perturbation (MP2) methods, were used to make zero-point energy and thermal corrections to electronic energies. Some semi-empirical methods and molecular mechanics force fields were also employed for comparison. The rotational barrier (3.81 kcal mol-1) predicted from the HF/6-311+G(3df) method is close to the measured electron diffraction value of 4.40 kcal mol-1 (-0.90,+1.10). The MP2/6-311G(d) level gives a lower barrier of 3.33 kcal mol-1, and the best MP3 calculation, MP3/6-311+G(3df)//MP2/6-311G(d), a value of 3.55 kcal mol-1.

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