INVESTIGADORES
DEFONSI LESTARD Maria Eliana
artículos
Título:
Experimental ant theoretical studies of the vibrations and structure of CF3CO2CH2CF3
Autor/es:
M. E. DEFONSI LESTARD; M. E. TUTTOLOMDO; E. L VARETTI; D. A. WANN; H. E. ROBERTSON; D. W. H. RANKIN; A. BEN ALTABEF
Revista:
Journal Molecular Structure
Editorial:
Elsevier science bv
Referencias:
Lugar: Inglaterra; Año: 2009 vol. 917 p. 183 - 192
Resumen:
The molecular structure of 2,2,2-trifluoroethyl
trifluoroacetate, CF3CO2CH2CF3, has been determined in
the gas-phase from electron-diffraction data
supplemented by ab initio
(MP2) and DFT
calculations using
basis sets up to 6-311++G(d,p). Both experimental and
theoretical data indicate that, although both structures
with anti, anti (Cs) and anti, gauche (C1) conformations exist by rotating about
the OAC(H2) bond, the
anti, anti structure is preferred. The difference in
free energy was calculated to be 2.1 kJ mol_1 (Cs conformer
lower in energy) and as the C1 conformer has a
double multiplicity relative to the Cs conformer,
the ratio of C1?Cs conformer was predicted to be 0.41: 0.59.
This conformational preference was studied using the
total energy scheme and the natural bond orbital
partition scheme. Additionally, the total potential
energy has been deconvoluted using six-fold decomposition
in terms of a Fourier-type expansion. Infrared spectra
of CF3CO2CH2CF3 have been obtained for the
gaseous, liquid and solid phases and the Raman
spectrum for the liquid phase. Harmonic vibrational frequencies
and a scaled force field have been calculated, leading
to a final root-mean-square deviation of
7.3 cm_1.