INQUINOA   21218
INSTITUTO DE QUIMICA DEL NOROESTE
Unidad Ejecutora - UE
artículos
Título:
Experimental and theoretical studies of the vibrations and structure of 2,2,2-trifluoroethylacetate, CF3CO2CH2CF3
Autor/es:
M. E. DEFONSI LESTARD; M. E. TUTTOLOMONDO; E. L. VARETTI; D. A. WANN; H. E. ROBERTSON; D. W. H. RANKIN; A. BEN ALTABEF
Revista:
JOURNAL OF MOLECULAR STRUCTURE
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Año: 2009 vol. 917 p. 183 - 192
ISSN:
0022-2860
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 C1Cs 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.