Fourier transform ion cyclotron resonance study of the dehydrogenative polymerization of allene and propyne induced by W⁺ in the gas phase

A Fourier transform ion cyclotron resonance study of the gas‐phase reaction of W⁺ with allene is reported. W⁺ successively dehydrogenates at least nine allene molecules, leading to the formation of a series of WC_3nH 2n+ ions, with WC₂₇H 18+ as the largest product observed after a reaction delay of 40 s. Starting from the third reaction, there is a competition between elimination of H₂ and C₂H₂ at each step. The activation of propyne was also investigated and found to lead to essentially the same sequence as with allene. The reaction of W⁺ with 1,1‐d₂‐allene and collision‐induced dissociation spectra of product ions are used to discuss a plausible mechanism for the formation and structures of some of the species observed.