Structure and formation of gaseous [C4H5O]+ ions. IV—Ions derived from the cyclopropenium ion [C3H3]+

Characterization of C₄H₅O]⁺ ions in the gas phase using their metastable ion and collisional activation spectra shows that the three isomeric ions HC?C? \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}H? OCH₃, CH₃O? \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}?C?CH₂ and ? OCH₃ related to the two stable C₃H₃]⁺ cations HC?C? CH₂]⁺ and are stable for ≥ 10^?5s. In contrast to the formation of cyclopropenium ions, it is found that the methoxy cyclopropenium ion is not generated from acyclic precursor molecules. The small but significant intensity differences found in the collisional activation spectra of C₃H₃]⁺ ions generated from HC?C? CH₂I and HC?C? CH₂Cl possibly indicate the presence of C₃H₃]⁺ ions of different structures.