Kinetic Energy Release Distribution in the Dissociation of Toluene Molecular Ion. The Tropylium vs Benzylium Story Continues

Production of C₇H₇⁺ from toluene molecular ion (TOL^·+) was studied using mass-analyzed ion kinetic energy spectrometry. The kinetic energy release distribution (KERD) was determined, which showed that both benzylium (Bz⁺) and tropylium (Tr⁺) ions were produced from TOL^·+. The interconversion between the molecular ions of toluene and cycloheptatriene prior to the dissociations was confirmed. Ab initio calculations at the HF/6-31G** and G2(MP2,SVP) levels were carried out for some important chemical species. The KERD in the Bz⁺ channel was calculated using the statistical phase space theory, while classical trajectory calculations were done to obtain the theoretical KERD in the Tr⁺ channel. The Tr⁺/Bz⁺ branching ratio determined by analyzing the experimental KERD was much larger than reported previously.