Syntheses, structures, and reactivities of novel silacyclic systems: the first stable silabenzene and silacyclopropabenzene

The first stable silabenzene and silacyclopropabenzenes were synthesized by taking advantage of an efficient steric protection group, 2,4,6-tris[bis(t rimethylsilyl)methyl]phenyl (Tbt). The molecular geometries of these novel conjugated ring systems containing a silicon atom were definitive) determin ed by X-ray crystallographic analysis. Their spectral data such as H-1. C-1 3, and Si-29 NMR, Fr-Raman, and UV-vis spectra and the theoretical calculat ions revealed their unique properties.