Persilastaffanes: silicon frameworks with delocalized sigma electrons

Jan 09, 2012
Persilastaffanes: silicon frameworks with delocalized sigma electrons

(PhysOrg.com) -- Persilastaffanes are an unusual new class of compounds that are introduced in the journal Angewandte Chemie by Japanese researchers led by Takeaki Iwamoto at Tohoku University. They are rod-shaped molecules with a core consisting of one or more tiny “cages” made of silicon atoms. Even more unusual than the name and structure of these materials are the properties of their electrons, which make the materials intriguing candidates as building blocks to make new materials for electronic applications.

Where does the name persilastaffane come from? Persila indicates an organic molecule in which all (“per”) carbon atoms are replaced by silicon atoms (“sila”). A staffane is a special arrangement of five carbon atoms: two “bridgeheads” are bound to each other by way of three “bridges”, each of which has a carbon atom at its center. This results in a cage-like spatial structure. Alternatively, the structure of the cage can be viewed as a wavy ring made of four carbon atoms in which two opposite sides are additionally bridged by another carbon atom. A persilastaffane is a molecule that contains this type of cage made out of silicon atoms.

The Japanese team has developed a synthetic technique to make containing one, two, or three such cages. What is so fascinating about these rod-shaped molecules? To date, there have been few studies of linear chains of silicon-containing ring systems; however theory suggests that there should be significant interactions between the cages. In these cases, the bonding electrons (sigma electrons) in the silicon–silicon bonds should not be localized between the two bonding partners as is usual in chemical bonds; instead, they should be able to move freely (delocalized) over the entire three-dimensional framework of , as in solid silicon.

This property is very interesting because silicon with delocalized sigma electrons absorb light in the UV range, as well as being light-sensitive or conducting. They can also become conducting under light. Iwamoto and his colleagues examined the tiny rods by spectroscopic methods. They were able to confirm considerable delocalization of the sigma electrons over the silicon cages. Iwamoto remarks: “Persilstaffanes are fascinating rod-shaped silicon molecules that could serve as linear connectors for novel silicon-based finely defined materials, such as conductive molecular wires.”

Explore further: New insights on carbonic acid in water

More information: Takeaki Iwamoto, Persilastaffanes: Design, Synthesis, Structure, and Conjugation between Silicon Cages, Angewandte Chemie International Edition, dx.doi.org/10.1002/anie.201106422

Related Stories

Wired up and ready to glow

Dec 10, 2010

Thirty years ago, no one believed that elements other than carbon, nitrogen, and oxygen could form double bonds at room temperature. But the discovery of 'kinetic protection' ligands -- large, bulky molecules ...

A diamond ring sparks a paradigm shift

Jun 06, 2011

The sweet smell of benzene gave birth to the term ‘aromatic’ molecules, but it is the chemical bonds within these compounds that have fascinated researchers for almost 200 years. Encasing alternating ...

Could silicon be ideal in quantum computing?

Sep 16, 2011

(PhysOrg.com) -- "Quantum computing could provide a way to significantly speed up the way we process certain algorithms," Malcolm Carroll tells PhysOrg.com. "The primary issue, though, is that you need a well controlled two-le ...

Recommended for you

World's fastest manufacture of battery electrodes

5 hours ago

New world record: Scientists at the Karlsruhe Institute of Technology (KIT) increased the manufacturing speed of electrode foils coated batch-wise by a factor of three – to 100 meters per minute. This was ...

Waste, an alternative source of energy to petroleum

5 hours ago

The group led by Martín Olazar, researcher in the UPV/EHU-University of the Basque Country's Department of Chemical Engineering, is studying the development of sustainable refineries where it is possible ...

Researchers developing new thermal interface materials

6 hours ago

In the microelectronics world, the military and private sectors alike need solutions to technologic challenges. Dr. Mustafa Akbulut, assistant professor of chemical engineering, and two students lead a project ...

New insights on carbonic acid in water

20 hours ago

Though it garners few public headlines, carbonic acid, the hydrated form of carbon dioxide, is critical to both the health of the atmosphere and the human body. However, because it exists for only a fraction ...

User comments : 0