par Panchenko, Yurii;Bock, Charles;Larkin, Joseph J.D.;Abramenkov, Alexander;De Mare, George 
;Banaru, Alexandru A.M.
Référence Russian Journal of Physical Chemistry, 85, 12, page (2156-2164)
Publication Publié, 2011-12
;Banaru, Alexandru A.M.Référence Russian Journal of Physical Chemistry, 85, 12, page (2156-2164)
Publication Publié, 2011-12
Article révisé par les pairs
| Résumé : | Scaled quantum mechanical force field (SQM-FF) vibrational analyses of the gauche,Trans,trans,Trans,gauche-conformers of octa-1,3,5,7-tetraene (I) with C i and C 2 symmetry at the HF/6-31G//HF/6-31G computational level were used to identify the rotational isomer observed in the IR spectrum of this excited molecule in the solid state. Geometry optimizations at the MP2(FC)/aug-cc-pVDZ level show that the two non-planar structures of gTtTg-I have the terminal -CH=CH 2 moieties rotated by ∼30.6° with respect to the remainder of the nearly planar skeleton. The MP2 and HF energies of the C 2 conformer are slightly lower than the corresponding values of the C i conformer. A set of the experimental wavenumbers relating to the C 2 conformer was determined by the detailed analyses of the experimental IR spectra of compounds obtained by Datta et al. via photolysis of 1,3,5-cycloterraene and bicycle[4.2,0]octa-2.4-diene. The available experimental wavenumbers correlate better with the results of our SQM-FF calculations at the HF/6-31G level for the conformer with C 2 symmetry than for the conformer with C i symmetry. In further support of these results, the van der Waals molecular volume of the C 2 conformer was calculated to be somewhat smaller than the volume of the C i conformer, suggesting that in the solid state, where the close-packing principle comes into play, the C 2 conformer would be preferred. © 2011 Pleiades Publishing, Ltd. |
