Phenylene-bridged cross-conjugated 1,2,3-trisilacyclopentadienes

Abstract

1,2,3-Trisilacyclopentadienes are obtained from the reactions of cyclotrisilene c-Si3R4 (R = iPr3C6H2) with phenyl and diphenyl acetylene, respectively. With 1,4-diethynyl benzene the crossconjugated bridging of two of the Si3C2 cycles by a paraphenylene linker is achieved. UV/ vis spectroscopy indicates a small but significant effect of cross-conjugation, which is confirmed by TD-DFT calculations. The formation mechanism of the 1,2,3trisilacyclopentadienes is elucidated by VT NMR.