Negative-ion mass spectra of heteroorganic compounds of group IV

Conclusions The dissociative resonance capture of electrons by the molecules of heteroorganic compounds of group IV was studied. It was shown that a new resonance state is observed with the introduction of a vinyl substituent. The nonadditive increase in the relative cross section for the formation of the negative ion with increase in the number of vinyl substituents is due to the stabilization of the molecule negative ion by * -* interaction.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 566–571, March, 1986.     

Negative-ion mass spectra of diterpene alkaloids with the keto group in the 6- or 7-position

Processes resulting in the formation of negative ions by molecules of some diterpene alkaloids via resonance electron capture have been studied. The mass spectra of these compounds have a small number of lines represented largely by intense peaks in the thermal electron energy region and are due to electron capture onto the lower unoccupied molecular orbital, which is π*-C=O or π*-Ph-C=O in character.     

Resonance electron capture by uracil derivatives

The enol forms of uracil and its derivatives were detected in the gas phase by mass spectrometry. The [M - H]⁻ ion is produced by resonance electron capture to the lowest unoccupied molecular orbitals, the process being accompanied by the detachment of the hydrogen atom from the nitrogen atom of the diketo form (low-energy peak at 0.8 eV) and from the oxygen atom of the enol form (in the energy region of 1.4 eV). The gas phase contains ∼10⁻³% of the enol form. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1360–1362, June, 2005.     

Resonance electron capture mass spectra of some diterpenoid alkaloids

Formation of negative ions from molecules of some diterpenoid alkaloids under conditions of resonance electron capture was studied. Ions formed by capturing low-energy electrons in the lowest unoccupied molecular orbital similar to the *-C=O or *-Ph—CO₂ orbitals contribute predominantly to the mass spectra.     

Sulfur ylides

The mass spectra of negative ions of keto-stabilized sulfur and phosphorus ylides (obtained from amino acids) and products of their thermal conversion are studied. The most characteristic peaks in the mass spectra of ylides belong to negative molecular ions and to [M−H]⁻ ions. Peaks of fragment ions in the mass spectra of ylides and products of their thermal conversion coincide both in mass numbers and resonance energies. For Part 8, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2100–2103, November, 1999.     

Dissociative electron capture by sulfide,sulfoxide, and sulfone molecules

Conclusions The low energy resonance in the negative ion mass spectra of alkyl vinyl, 2,3-epoxypropyl alkyl, and 2, 3-epithiopropyl alkyl sulfies and their sulfoxide and sulfone analogs is related to electron capture in the ^* orbital of the S-C bond. The oxidation state of the sulfur atom has no qualitative effect on the major processes involved in the formation of the negative ions.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, 1653–1657, July, 1984.     

Mass spectra of negative ions of nitrones and isomeric O-ethers of oximes

Conclusions Interconversion of the studied nitrones and corresponding O-ethers of oximes fails to occur during the capture of low-energy electrons, and the mass spectra of the DRCE make it possible to distinguish valence isomers of this type.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1388–1391, June, 1979.