Dehydrocoupling catalyst development

Woo recently developed a rapid, highly linear-selective dehydrocoupling catalyst system of phenylsilane CpjMCL/Hydride (C p = C5H5 or C5Me5 M = Ti, Zr, Hf Hydride = Red-Al, Selectride, Super Hydride) combination catalysts [Eq. (2)].11,17... 

Because of these limitations, considerable effort has been focused on the development of new synthetic routes to polysilanes. The early transition metal-catalysed dehydrocoupling process discovered in 1985 [eqn (10.8)] is potentially very attractive however, the molecular weights of the polysilanes formed to date are generally fairly low (Mn<8000)." The catalysts used for these coupling reactions are usually titanocene or zirconocene derivatives." " " ... 

The future challenges in this area will be the development of catalyst sytems that promote the formation of higher molecular weight material and that also have the ability to control the microstructure of the polymer. Other features for new catalyst systems would involve the ability to distinguish between primary, secondary, and tertiary centers and couple both alkylsilanes and arylsilanes efficiently. To achieve these goals will require a better understanding of the mechanistic pathways for dehydrocoupling than is currently available. 

Jiang Y, Blacque O, Fox T, Freeh CM, Berke H (2009) Development of rhenium catalysts for amine borane dehydrocoupling and transfer hydrogenation of olefins. Oiganometallics 28 5493-5504... 

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