Electrospray ionization (ESI) of tetrameric platinum(II) acetate, [Pt₄(CH₃COO)₈], in methanol generates the formal platinum(III) dimeric cation [Pt₂(CH₃COO)₃(CH₂COO)(MeOH)₂]⁺, which, upon harsher ionization conditions, sequentially loses the two methanol ligands, CO₂, and CH₂COO to form the platinum(II) dimer [Pt₂(CH₃COO)₂(CH₃)]⁺. Next, intramolecular sequential double hydrogen-atom transfer from the methyl group concomitant with the elimination of two acetic acid molecules produces Pt₂CH⁺ from which, upon even harsher conditions, PtCH⁺ is eventually generated. This degradation sequence is supported by collision-induced dissociation (CID) experiments, extensive isotope-labeling studies, and DFT calculations. Both PtCH⁺ and Pt₂CH⁺ react under thermal conditions with the hydrocarbons C₂H_n (n=2, 4, 6) and C₃H_n (n=6, 8). While, in ion–molecule reactions of PtCH⁺ with C₂ hydrocarbons, the relative rates decrease with increasing n, the opposite trend holds true for Pt₂CH⁺. The Pt₂CH⁺ cluster only sluggishly reacts with C₂H₂, but with C₂H₄ and C₂H₆ dihydrogen loss dominates. The reactions with the latter two substrates were preceded by a complete exchange of all of the hydrogen atoms present in the adduct complex. The PtCH⁺ ion is much less selective. In the reactions with C₂H₂ and C₂H₄, elimination of H₂ occurs; however, CH₄ formation prevails in the decomposition of the adduct complex that is formed with C₂H₆. In the reaction with C₂H₂, in addition to H₂ loss, C₃H₃⁺ is produced, and this process formally corresponds to the transfer of the cationic methylidyne unit CH⁺ to C₂H₂, accompanied by the release of neutral Pt. In the ion–molecule reactions with the C₃ hydrocarbons C₃H₆ and C₃H₈, dihydrogen loss occurs with high selectivity for Pt₂CH⁺, but in the reactions of these substrates with PtCH⁺ several reaction routes compete. Finally, in the ion–molecule reactions with ammonia, both platinum complexes give rise to proton transfer to produce NH₄⁺; however, only the encounter complex generated with PtCH⁺ undergoes efficient dehydrogenation of the substrate, and the rather minor formation of CNH₄⁺ indicates that CN bond coupling is inefficient.

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