The methanium ion, CH5+. Evidence for the structure of a nonclassical ion from reaction studies by ion cyclotron resonance spectroscopy

Studies of proton and deuteron transfer from methanium ions to various substrates and collision-induced dissociation of isotopically substituted methanium ions suggest that under the low-energy conditions of the ICR experiment, the addition of a hydrogen ion to methane produces a methanium ion whose hydrogens are structurally and chemically distinguishable. The reactions of methanium ions formed in the low energy electron impact ionization of CH4–CD4 mixtures are compatible with a methanium ion of Cs symmetry in which intramolecular rearrangement does not occur. Reaction studies on the methanium ions formed by the exoergic proton transfer from D3+ to methane indicate that rapid intramolecular rearrangements occur in these ions.