TRANSLATIONAL ENERGY-RESOLVED COLLISIONALLY ACTIVATED METHYL CATION TRANSFER FROM PROTONATED METHANE TO AGRON, KRYPTON, AND XENON AND FROM PROTONATED FLUOROMETHANE TO ARGON AND MOLECULAR-OXYGEN

Translational energy-resolved collisionally activated gas-phase reactions of protonated methane with argon, krypton, and xenon and of protonated fluoromethane with argon and molecular oxygen are studied using the method of Fourier transform ion cyclotron resonance mass spectrometry. It appears that translationally activated protonated methane can act as a methyl cation donor if the competing proton transfer is energetically less favored. Translational energy-resolved collisionally activated reactions between protonated methane and argon, krypton, and xenon reveal that the methyl cation transfers resulting in the formation of methylargonium, methylkryptonium, and methylxenonium ions all proceed via transition states which are about 0.6 eV higher in energy than the reactants. The results suggest that in these transition states the weakening of the two-electron three-center C-H-H bond in protonated methane is more advanced than the bond formation between the methyl group and the noble gas atom. Similarly, translationally activated protonated fluoromethane can transfer a methyl cation to argon and molecular oxygen via transition states which are about 0.3 and 0.4 eV higher in energy than the reactants, respectively. It is shown that the product ion from the methyl cation transfer from protonated fluoromethane to molecular oxygen has the methylperoxy cation structure.