Mass spectra of silylindolizines, dihydrosilanaphthoindolizine and dihydrosilaazaaceanthrelenes

Abstract

The electron impact fragmentation of compounds from the series of silylindolizines, dihydrosilanaphthoindolizines, and dihydrosilaazaaceanthrelenes has been studied. For indolizines having an exocyclic silicon atom, carbomethoxy and benzoyl groups attached to the five membered ring, the loss of the OCH 3 species from the carbomethoxy groups and the hydrocarbon radical from the silicon atom takes place with almost equal intensity. In the case of dihydrosilanaphthoindolizines the expulsion of the OCH 3 group from the carbomethoxy substituents is the most pronounced fragmentation route; moreover, a sharp fall in the intensity of their molecular ion peak (about 5 times) is registered. The main fragmentation route during the dissociative ionisation of silaazaaceanthrelenes, in contrast to silylindolizines and silanaphthoindolizines, is the loss of the hydrocarbon radical attached to the nitrogen atom, and not the substituents at the silicon atom, or the OCH 3 species from the carbomethoxy groups. Such properties can be used for the purpose of structural analysis.