Gas-phase proton transfer from dications: Coulombic repulsion between reaction products in C60H2+Â +Â B (BÂ =Â C3H3N, HCN and CO)

B3LYP/6-311+G**//B3LYP/6-31G* calculations are carried out on C60z+ species (z = 0-3), C60H+, C60H2+ and on the potential energy surfaces for proton transfer from C60H2+ to CH2CHCN, HCN and CO. Reasonable agreement is obtained with experiment for the C60 species, although the second and third ionization potentials are too low. The calculated potential energy surfaces account for observed reactivity. Analysis of the charge distribution in the TS for proton transfer to HCN helps explain the origin of the Coulombic barrier.