par De Mare, George 
;Peterson, Michael R.
Référence Journal of molecular structure, 89, 1-2, page (213-225)
Publication Publié, 1982-09
;Peterson, Michael R.Référence Journal of molecular structure, 89, 1-2, page (213-225)
Publication Publié, 1982-09
Article révisé par les pairs
| Résumé : | The geometry of vinylcyclopropane has been completely optimized at each critical point by analytic gradient (force) methods at the minimal STO-3G and the split-valence 3-21G basis set levels. The geometries obtained for the various critical points have been used to generate potential energy curves for vinyl group rotation within the rigid rotor approximation. Comparison of these curves clearly demonstrates the importance of complete geometry optimization. The potential energy curve for vinyl group rotation, generated with the s-trans STO-3G optimized geometry, predicts secondary gauche minima which are an artifact of the rigid rotor approximation. With complete geometry optimization along the curve, the STO-3G basis set computations predict only s-trans and s-cis minima. In contrast, the complete optimizations with the 3-21G basis set, in agreement with experiment, predict a three-fold rotational contour with two equivalent gauche minima. These minima lie 6.86 kJ mol-1 above the s-trans minimum. The computed barrier to rotation for the s-truns - gauche interconversion is 13.3 kJ mol-1. The electric dipole moment computed with the 3-21G basis for the s-trans 3-21G optimized geometry is 0.446 D or about 10% less than the experimental value. © 1982. |
