Decarboxylation of Metastable Methyl Benzoate Molecular Ions

By using a combination of mass spectrometric methodologies and density functional theory calculations [DFT/B3LYP/6-311 ++ G(d, p)], it is proposed that the decarboxylation of metastable methyl benzoate molecular ions occurs via distonic and ion-neutral complex (INC) intermediates. The same INC involving a complex between the benzyl radical and protonated carbon dioxide is also generated upon decarboxylation of metastable phenylacetic acid molecular ions. Internal proton transfer within the INC produces in fine a mixture of toluene and isotoluene radical cations.