Gas phase reactivities of isomeric ions: Methylenediphenylcyclopropane and diphenylmethylenecyclopropane

C. ‐J Pineda, H. D. Roth, A. M. Mujsce, M. L. Schilling, W. D. Reents

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Gas phase ion/molecule reactions have been used to probe the structure of ions obtained by electron impact upon 1‐(diphenylmethylene)cyclopropane and 2,2‐diphenyl‐1‐methylenecyclopropane. The resulting ions of molecular composition C16H14 (m/z 206+) were reacted with charge transfer reagents (6·9 < IP < 8·8eV), giving evidence for the presence of isomeric ions with different reactivities. The less reactive ion is identified as a trimethylenemethane species (TMM+) in which one cyclopropane bond is broken; the more reactive ions are assigned as vertical ions in which the cyclopropane ring is unaffected. The vertical ions have recombination energies of 8·44 ± 0·05eV, whereas TMM+ has one of 7·41±0·05eV. The TMM+ fraction is not constant; it increases with increasing IP of the reagent. This is attributed to a reagent‐catalyzed isomerization of the vertical ion to TMM+. In addition, the reagent ions are observed to undergo a unique reaction with the neutral methylenecyclopropane derivatives: electron transfer and ring opening to yield TMM+. These findings limit the application of the customary equilibrium measurements as a method to determine the substrate IP.

Original languageEnglish (US)
Pages (from-to)117-130
Number of pages14
JournalJournal of Physical Organic Chemistry
Issue number2
StatePublished - Mar 1989
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry


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