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

Abstract Characterization of [C 4 H 5 O] + ions in the gas phase using their metastable ion and collisional activation spectra shows that the three isomeric ions HCC $$ \mathop {\rm C}\limits^{\rm + } $$ HOCH 3 , CH 3 O $$ \mathop {\rm C}\limits^{\rm + } $$ CCH 2 and OCH 3 related to the two stable [C 3 H 3 ] + cations [HCCCH 2 ] + and are stable for ≥ 10 −5 s. 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 [C 3 H 3 ] + ions generated from HCCCH 2 I and HCCCH 2 Cl possibly indicate the presence of [C 3 H 3 ] + ions of different structures.