Dehydrocoupling of Ethylene Disilanes Catalyzed by Group 4 Metallocene Combination

다국어 초록 (Multilingual Abstract)

Inorganic polymers such as polycarbosilanes and polysilanes have been employed for many special applications. Polycarbosilanes have been used as SiC ceramic precursor. Polysilanes possess peculiar optoelectronic properties due to σ-conjugation along the silicon backbone and have received great attention as silicon-containing ceramic precursors, luminesecnt materials, deep-UV positive photoresists, electroconductors, and photoinitiators. The conventional synthetic method to prepare high-molecular-weight polysilanes is the Wurtz coupling reaction of dichlorosilanes using an alkali metal dispersion in either toluene-refluxing temperature or supersonic activation. However, the heterogeneous reductive dehalocoupling method has some limitations such as intolerance of some functional groups, lack of reproducibility, and difficulties in controlling stereochemistry and molecular weight. Recently, the group 4 metallocene-catalyzed dehydrocoupling of hydrosilanes to polysilancs was discovered. Considerable efforts have been made to increase the molecular weight of the polysilanes in the homogeneous catalytic dehydrocoupling of hydrosilanes.
We reported the dehydropolymerization of various hydrosilanes catalyzed by group 4 metallocene complexes generated in situ from Cp_(2)MCI_(2)/Red-Al combination. Hydrosilation has been used to increase the molecular weight of polysilanes containing both Si-H and olefin moieties. Corriu et al. recently accounted the tunable dchydropolymerization of an ethylene disilane, 1,4-disilapentane to highly cross-linked insoluble polysilane as a silicon carbide precursor. We preliminarily noted the hydrogenation/dehydrocoupling of ethylene disilanes catalyzed by the Cp_(2)TiCl_(2)/Red-Al combination. Here we report the hydrogenation/hydrosilatiom/dehydrocoupling of 2,5-disilaoct-7l-ene (1) and the dehydrocoupling of 2,5-disilahexane (2), catalyzed by group 4 metallocene complexes generated in situ from Cp'_(2)MCl_(2)/ Hydride [Cp' = η^(5)-C_(5)H_(5)(Cp), η^(5)-C_(5)Me_(5)(Cp*); M=Ti, Zr, Hf; Hydride = Red-Al, N-Selectride] combination.

목차 (Table of Contents)

• Experimental Section
• Result and Discussion
• References