Featured Research

from universities, journals, and other organizations

Chemists Discover Molecule Considered Too Unstable To Exist

Date:
April 12, 2002
Source:
Northwestern University
Summary:
Organic chemistry textbooks will need to be revised to recognize a chemical species that chemists have discovered at Northwestern University. The species — pentamethylcyclopentadienyl cation — was thought not to exist for long because theory said it was unstable.

EVANSTON, Ill. — Organic chemistry textbooks will need to be revised to recognize a chemical species that chemists have discovered at Northwestern University. The species — pentamethylcyclopentadienyl cation — was thought not to exist for long because theory said it was unstable.

"I’ve said this molecule is unstable and doesn’t exist dozens of times in organic chemistry class, but, as it turns out, the molecule had different ideas," said Joseph B. Lambert, Clare Hamilton Hall Professor of Chemistry at Northwestern. He and graduate student Lijun Lin discovered that the cation (a positively charged ion) is stable in the solid state for weeks at room temperature and in solution.

The preparation of the cation and the solving of its X-ray structure are reported in the April 15 issue of the chemistry journal Angewandte Chemie.

The cyclopentadienyl cation is a common textbook example of an antiaromatic molecule, a molecule so electronically unstable and, therefore, extremely reactive that it should not exist for any length of time. Lambert believes the cation now should be described as nonaromatic.

The last example of the synthesis of a simple, stable molecule with the electronic configuration of antiaromaticity — cyclooctatetraene — was in 1913.

Lambert and Lin discovered the molecule when trying to figure out how to make stable organic cations in the laboratory. When Lin came to Lambert with the crystal structure of a molecule other than the one expected, Lambert quickly recognized the structure as an example of the elusive cyclopentadienyl cation of textbook fame.

They found that the cation was stable in the open atmosphere at room temperature. The cation achieves this stability by avoiding interactions among electrons. This condition is known as localized bonding. Normally molecules are stabilized by delocalization of electrons, whereby they may be located in more than one part of the molecule. For unsaturated, cyclic molecules, delocalization usually results in heightened stability. Such molecules have been termed aromatic.

For certain electron configurations, however, delocalization lessens stability, and such molecules have been called antiaromatic. It was thought that the cyclopentadienyl cation ought to be antiaromatic and hence unstable, because its electronic configuration corresponds to that predicted by theory to be antiaromatic.

"We didn’t realize there would be this localized alternative," said Lambert. "Now we have to rethink the properties of antiaromaticity."

Lambert and Lin currently are studying the chemistry of the pentamethylcyclopentadienyl cation by carrying out reactions with the cation to learn more about its properties.

The third author on the paper is Vitaly Rassolov, of the University of South Carolina, Columbia, who carried out theoretical calculations. The research was supported by the National Science Foundation.


Story Source:

The above story is based on materials provided by Northwestern University. Note: Materials may be edited for content and length.


Cite This Page:

Northwestern University. "Chemists Discover Molecule Considered Too Unstable To Exist." ScienceDaily. ScienceDaily, 12 April 2002. <www.sciencedaily.com/releases/2002/04/020412074739.htm>.
Northwestern University. (2002, April 12). Chemists Discover Molecule Considered Too Unstable To Exist. ScienceDaily. Retrieved October 21, 2014 from www.sciencedaily.com/releases/2002/04/020412074739.htm
Northwestern University. "Chemists Discover Molecule Considered Too Unstable To Exist." ScienceDaily. www.sciencedaily.com/releases/2002/04/020412074739.htm (accessed October 21, 2014).

Share This



More Matter & Energy News

Tuesday, October 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Graphene Paint Offers Rust-Free Future

Graphene Paint Offers Rust-Free Future

Reuters - Innovations Video Online (Oct. 21, 2014) British scientists have developed a prototype graphene paint that can make coatings which are resistant to liquids, gases, and chemicals. The team says the paint could have a variety of uses, from stopping ships rusting to keeping food fresher for longer. Jim Drury reports. Video provided by Reuters
Powered by NewsLook.com
Gulfstream G500, G600 Unveiling

Gulfstream G500, G600 Unveiling

Flying (Oct. 20, 2014) Watch Gulfstream's public launch of the G500 and G600 at their headquarters in Savannah, Ga., along with a surprise unveiling of the G500, which taxied up under its own power. Video provided by Flying
Powered by NewsLook.com
Japanese Scientists Unveil Floating 3D Projection

Japanese Scientists Unveil Floating 3D Projection

Reuters - Innovations Video Online (Oct. 20, 2014) Scientists in Tokyo have demonstrated what they say is the world's first 3D projection that floats in mid air. A laser that fires a pulse up to a thousand times a second superheats molecules in the air, creating a spark which can be guided to certain points in the air to shape what the human eye perceives as an image. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

3BL Media (Oct. 20, 2014) Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-fuel Impala Video provided by 3BL
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins