A Theoretical Investigation on the Reaction Mechanism of the C 9 H 12 +· Side-chain Decomposition

n-Phenylpropane cation C9H12+· serves as a prototype to investigate the reaction mechanisms of alkylbenzene cations. The decomposition reactions of C9H12+· system have been studied extensively at the B3LYP/6-311++G∗∗ level with Gaussian 98 program package. All reaction channels were fully investigated with the vibrational mode analysis to confirm the transition states and with electron population analysis to discuss the electron redistribution, and to elucidate the reaction mechanism. The reaction mechanism shows that there is a non-barrier channel of C9H12+·C7H7++C2H5·, which is thermodynamically most favorable.