Anti, ortho, and gauche conformers of perfluoro-n-butane: Matrix-isolation IR spectra and calculations
Artikel i vetenskaplig tidskrift, 1996

Nitrogen matrix-isolation IR spectra have been obtained for each of the three conformers of n-C4F10 (gauche, ortho, and anti) by trapping a hot conformer mixture on a cold CsI window and subsequent matrix annealing and spectral differencing. They were assigned by comparison with results of HF/6-31G* calculations, and the nature of the normal modes has been analyzed using the total energy distribution procedure. At the fully optimized MP2/6-31G* (frozen core) level, the CCCC dihedral angles and relative energies (kcal/mol) are 54.2 degrees and 0.68 (gauche), 94.8 degrees and 1.63 (ortho), and 165.5 degrees and 0 (anti). Single-point MP2/6-311G* (frozen core) relative energies at these geometries are 0.85, 2.12, and 0 kcal/mol, respectively. Only a minute amount of the ortho conformer is trapped in nitrogen matrix, and none in other matrices that were tried. A variation of the relative intensities of IR peaks of the gauche and anti conformers as a function of the temperature of the gas before deposition yields an ''average'' Delta H value of about 0.9 kcal/mol, with the anti conformer more stable. The temperature range covered was too small to reveal the expected bilinear nature of the van't Hoff plot.


Bo Albinsson

Institutionen för fysikalisk kemi

J. Michl

Journal of Physical Chemistry

0022-3654 (ISSN)

Vol. 100 3418-3429


Nanovetenskap och nanoteknik


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