ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 49, Number 3
JKCSEZ 49(3)
June 20, 2005 

The equilibrium structures and relative energies for the local minima and transition states which can exist on the rearrangement pathway of C₇H₇⁺ ions (o-, m-, and p-tolyl, benzyl, or tropylium cations) have been investigated using ab initio quantum mechanical techniques with various basis sets. The structures of all these possible intermediates have been fully optimized SCF, CCSD, and CCSD(T) levels of theory with the DZ and DZP basis sets. The SCF harmonic vibrational frequencies were also evaluated to identify the potential minimum or transition state for an optimized structure. At the highest level of theory employed in this work, the activation energy barriers are predicted to be 40.0 kcal/mol for the rearrangement going from p- to m-tolyl and 40.9 kcal/mol between m- and o-tolyl including zero-point vibrational energy corrections. Also the activation energy barriers are predicted to be 25.1 kcal/mol for the rearrangement going from o-tolyl to benzyl cation and 67.8 kcal/mol between benzyl and tropylium cation.