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 September 19, 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 September 19, 2014).

Share This



More Matter & Energy News

Friday, September 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

MIT BioSuit A New Take On Traditional Spacesuits

MIT BioSuit A New Take On Traditional Spacesuits

Newsy (Sep. 19, 2014) The MIT BioSuit could be an alternative to big, bulky traditional spacesuits, but the concept needs some work. Video provided by Newsy
Powered by NewsLook.com
Virtual Reality Headsets Unveiled at Tokyo Game Show

Virtual Reality Headsets Unveiled at Tokyo Game Show

AFP (Sep. 18, 2014) Several companies unveiled virtual reality headsets at the Tokyo Game Show, Asia's largest digital entertainment exhibition. Duration: 00:48 Video provided by AFP
Powered by NewsLook.com
Apple's iOS8 Includes New 'Killswitch' To Curb Theft

Apple's iOS8 Includes New 'Killswitch' To Curb Theft

Newsy (Sep. 18, 2014) Apple's new operating system, iOS 8, comes with Apple's killswitch feature already activated, unlike all the models before it. Video provided by Newsy
Powered by NewsLook.com
Stocks Hit All-Time High as Fed Holds Steady

Stocks Hit All-Time High as Fed Holds Steady

AP (Sep. 17, 2014) The Federal Reserve signaled Wednesday that it plans to keep a key interest rate at a record low because a broad range of U.S. economic measures remain subpar. Stocks hit an all-time high on the news. (Sept. 17) Video provided by AP
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:
from the past week

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