Synthesis and Reactions of a Stable 1,2-Diaryl-1,2-dibromodisilene: A Precursor for Substituted Disilenes and a 1,2-Diaryldisilyne

摘要

There has been much interest in the chemistry of multiply bonded organosilicon compounds, i.e., disilenes and disilynes. While numbers of kinetically stabilized disilenes have been synthesized and characterized since the isolation of the first stable disilene, Mes_2Si=SiMes_2 (Mes = mesityl), by West and his co-workers, only two examples of stable disilynes have been known up to now. Wiberg et al. and Sekiguchi et al. independently reported the synthesis of disilynes bearing bulky silyl groups, while theoretical studies suggest that a silyl group should afford thermodynamic stabilization toward the low-coordinated organosilicon compounds due to the electropositive silicon atom. Although a carbon-substituted disilyne has been desired as a new standard of a Si≡Si triple-bond compound, no example has been reported so far for a diaryl- or dialkyl-substituted disilyne. On the other hand, unique properties of disilenes prompted many chemists to explore the chemistry of novel systems containing Si≡Si units with extended π-conjugation from the standpoint of material science.6 Accordingly, a proper disilene unit as a "building block" has been desired for the synthetic studies of functionalized disilenes. Recently, the stable disilyne, R_(Si)Si≡SiR_(Si) (R_(Si) = Si[CH(SiMe_3)_2]2(i-Pr)), was evidenced to afford unique disilenes by addition reactions.