Inversion of the C-8 nonplanar ring

Abstract

Inversion of the recently reported non-planar cyclic minimum-energy structure of C-8 (D2d symmetry) is studied by means of the second-order Moller-Plesset perturbation treatment with the 6-31G* basis set. Two new planar cyclic saddle points have been found, possessing D4h and C2h, symmetry and exhibiting two and one imaginary frequencies, respectively. The former and the latter saddle point am located 71 and 54 kJ/mol, respectively, above the D2d minumum. Calculated harmonic vibrational frequencies for the activated complex C2h are presented.