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Deuterium labelling and thermochemical studies of dissociative ionization of methyl substituted monosilacyclobutanes. Ring expansion in the molecular ion of 1,1,3‐trimethyl‐1‐silacyclobutane
Author(s) -
Gusel'nikov L. E.,
Volkova V. V.,
Tarasenko N. A.,
Tishenkov A. A.,
Zaikin V. G.,
Eremina E. I.,
Nametkin N. S.
Publication year - 1981
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210160603
Subject(s) - electron ionization , chemistry , deuterium , ion , fragmentation (computing) , molecule , mass spectrometry , mass spectrum , polyatomic ion , ionization , standard enthalpy of formation , methyl radical , cyclobutane , analytical chemistry (journal) , ring (chemistry) , photochemistry , organic chemistry , radical , atomic physics , physics , chromatography , computer science , operating system
Dissociative ionization of 1,1‐dimethyl‐1‐silacyclobutane, 1,1‐bis(trideuteromethyl)‐1‐silacyclobutane, 1,1,3‐trimethyl‐1‐silacyclobutane, 1,1‐bis(trideuteromethyl)‐3‐methyl‐1‐silacyclobutane and 1,1,2‐trimethyl‐1‐sila‐cyclobutane have been studied. Low energy electron impact fragmentation of 1,1‐bis(trideuteromethyl)‐3‐methyl‐1‐silacyclobutane results mainly in the loss of ethene with the involvement of the C‐methyl group from the rearranged molecular ion. No fragment ions indicating rearrangement of the molecular ion have been detected in mass spectra of 1,1‐bis(trideuteromethyl)‐1‐silacyclobutane. The ionization energies for 1,1,3‐trimethyl‐1‐silacyclobutane, 1,1,2‐trimethyl‐1‐silacyclobutane and 1,1‐dimethyl‐1‐silacyclopentane, and also the appearance energies for the [M − 28] +˙ and [M − 42] +˙ ions, have been measured by photoioniza‐tion mass spectrometry. The heats of formation of these ions and of 1,1,3‐trimethyl‐1‐silacyclobutane and 1,1‐dimethyl‐1‐silacyclopentene molecules have been calculated as have the enthalpies of the transformation processes.