11-14-07
Chemists Discover Molecule Considered Too Unstable To Exist
EVANSTON, Ill., (2002), Chemists Discover Molecule Considered Too Unstable To Exist
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 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 non aromatic. 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.
By reading this article, I learned that a new molecule was discovered. People thought it was too unstable to exist but found that at certain temperatures, the molecule is stable.
