Silaethene : IV. Gasphasenpyrolyse von cyclopentadienyl-monosilacyclobutanen

The gas phase pyrolysis (625°C, 10−2 mbar) of cyclopentadiene, dicyclopentadiene and trimethylsilylcyclopentadiene as well as of the monosilacyclobutanes Cpdata (Cp=C5H5;R=Me, t-Bu, Cl) is described. In order to investigate the reaction pathways the copyrolysis of Me2SiCH2CH2CH2 and disilanes [Me3SiSiMe3, Me2ClSiSiClMe2, Me(Vi)SiSi(Vi)Me], respectively, with cyclopentadiene has been studied under the same conditions. The surprising formation of the aromatic systems benzene (main product) and toluene is interpreted on the basis of the sequence of intramolecular reactions of the silaethene intermediate Cp(R)SiCH2 (valence isomerisation, elimination).