Collision induced dissociations of carbanions in the gas phase: the formation of vinylidene carbene intermediates from deprotonated prop-2-ynyl ethers

Abstract

Evidence is presented which suggests that the anionic isomers MeO–CH₂–CC^– and CH₂CC^––OMe, upon collision activation in the gas phase, fragment through the vinylidene carbene intermediate [(CH₂CC:)MeO^–]. In particular, the intermediate eliminates CH₂O and MeOH to form C₃H₃^– and C₃H^–, respectively. Ab initio calculations indicate that the latter ion has a ground state triplet structure with ‘allenic’ type geometry.