ABINITIO MO CALCULATION ON THE ENERGY BARRIER FOR THE PENETRATION OF A BENZENE-RING BY A HELIUM ATOM - MODEL STUDIES FOR THE FORMATION OF ENDOHEDRAL HE-AT-THE-COST-OF-C60+ - COMPLEXES BY HIGH-ENERGY BIMOLECULAR REACTIONS

Ab initio MO calculations are reported for the C3v-symmetric penetration of C6H6 and C6H6+. by a helium atom. At the highest level of theory (MP2/6-31G**//MP2/3-21G*) barriers of 10.7 and 9.4 eV are obtained. The calculated binding energy of a helium atom to benzene is negligible. These computational results are in agreement with recent experiments on the successful formation of endohedral He@C60+. complexes and may contribute to the understanding of the penetration mechanism of fullerenes in high-energy bimolecular reactions in the gas phase.