Polysilane rings: Selective cyclopolymerization using transition metals

May 28, 2013
(a) Nickel-catalyzed polymerization to afford linear or cyclic polysilanes and (b) one of possible intermediates in the cyclopolymerization.

Polysilanes, composed of the Si–Si linkage, exhibit unique electronic and optical properties that result from the extensive delocalization of σ-electrons along the polymer backbones.

Transition-metal-catalyzed dehydrocoupling polymerization of organosilanes is the most common method for the synthesis of polysilanes. Early transition metals such as titanium and are effective catalysts to provide the linear polysilanes, while use of late transition metals (rhodium, palladium, etc.) have been much rarer than the early metals.

Now, Makoto Tanabe and his colleagues at Chemical Resources Laboratory of Tokyo Institute of Technology have found that a nickel complex is very effective for dehydrocoupling reactions of organosilanes, forming the cyclic polysilanes selectively.

The Ni/PMe3 catalytic system, prepared in situ, led to polycondensation of phenylsilanes to produce the linear polysilanes, similar to the results catalyzed by early transition metals. Similar reactions using a Ni/PMe2(CH2)2PMe2 system resulted in selective cyclopolymerization to yield cyclic polysilanes involving the 9-11 silicon units. Formation of a palladium tetrasilane ring complex implies it being a possible intermediate for formation of the cyclic polymers.

This study demonstrates the first controlled to produce linear or cyclic polysilanes by the appropriate choice of catalysts. The cyclic polysilanes might be interested in exhibiting the attributed to the cyclic conjugated structure.

Explore further: Recycling industrial waste water: Scientists discover a new method of producing hydrogen

More information: Tanabe, M. et al. Nickel-Catalyzed Cyclopolymerization of Hexyl- and Phenylsilanes, Organometallics 32, 1037 (2013). DOI: 10.1021/om301052f

add to favorites email to friend print save as pdf

Related Stories

Life's origins in need of metals

Sep 10, 2010

Scientists have proposed a new potential catalyst for jump-starting metabolism, and life itself, on the early Earth. Transition metals like iron, copper and nickel along with small organic molecules could ...

Photosynthesis: The last link in the chain

Jan 04, 2013

For almost 30 years, researchers have sought to identify a particular enzyme that is involved in regulating electron transport during photosynthesis. A team at Ludwig-Maximilians-Universität (LMU) in Munich has now found ...

Recommended for you

A greener source of polyester—cork trees

15 hours ago

On the scale of earth-friendly materials, you'd be hard pressed to find two that are farther apart than polyester (not at all) and cork (very). In an unexpected twist, however, scientists are figuring out ...

A beautiful, peculiar molecule

18 hours ago

"Carbon is peculiar," said Nobel laureate Sir Harold Kroto. "More peculiar than you think." He was speaking to a standing-room-only audience that filled the Raytheon Amphitheater on Monday afternoon for the ...

Metals go from strength to strength

Apr 15, 2014

To the human hand, metal feels hard, but at the nanoscale it is surprisingly malleable. Push a lump of metal with brute force through a right-angle mould or die, and while it might look much the same to the ...

User comments : 0

More news stories

Breakthrough points to new drugs from nature

Researchers at Griffith University's Eskitis Institute have developed a new technique for discovering natural compounds which could form the basis of novel therapeutic drugs.

A greener source of polyester—cork trees

On the scale of earth-friendly materials, you'd be hard pressed to find two that are farther apart than polyester (not at all) and cork (very). In an unexpected twist, however, scientists are figuring out ...