Thermochemical determination of structure of negative ions on the basis of data from resonance electron capture mass spectrometry. 1. Heterocyclic analogs of cyclopentadiene

Appearance energies have been measured for negative ions formed in the gas phase upon dissociative capture of electrons by molecules of cyclopentadiene, pyrrole, selenophene, thiophene, furan, and furan derivatives. From an analysis of the enthalpies of formation of the fragmentation products, it has been established that electron capture by molecules of C₄H₄X (X=O, S, Se, NH, CH₂) leads to the formation of ions with cyclic and acyclic structures.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 590–592, March, 1991.