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The isomerization and fragmentation of the straight-chain octanamine radical cations was studied with the aid of deuterium labeling and composite quantum chemical calculations with the G3 and G2 (MP2, SVP) methods. Metastable octan-1-amine molecular ions isomerize to octan-2-amine ions prior to cleavage, and metastable octan-2-amine molecular ions rearrange to the octan-3-amine isomer, but octan-1-amine ions do not isomerize to octan-3-amine, nor are the reverse reactions observed. The competition between cleavage and isomerization is determined by the respective energy barriers and by the internal energy distribution of the metastable molecular ions, which in turn depends on the critical energy for simple cleavage of the molecular ions. (Int J Mass Spectrom 199 (2000) 79 -89) Β© 2000 Elsevier Science B.V.
π SIMILAR VOLUMES
The syn dimer of cyclobutadiene (tricyclo[4.2.0.0(2.5)]octa-3,7-diene, TOD) is subjected to ionization under different conditions and the resulting species are probed by optical and ESR spectroscopy. By means of quantum chemical modelling of the potential energy surfaces and the optical spectra, it
Ionized 3-methylbutan-2-01 displays four low-energy fragmentations, loss of CH,' and C,H,' and loss of CH, and C,H, , the latter pair being produced by metastable ion decompositions. The electron-impact, metastableion and collision-induced dissociation mass spectra of I3C and 'H-labelled isotopomers