Single-Electron Bonds Observed Between Carbon Atoms

For over a century, chemists have believed that when atoms share one or more pairs of electrons, they form covalent bonds, a strong interatomic connection. Now, researchers have observed for the first time a single-electron covalent bond between two carbon atoms.

While this rare bonding behavior has been noted between certain atoms before, its presence between carbon atoms is particularly exciting for scientists given that carbon is a fundamental element of life on Earth and a crucial component in many industrial chemicals. This groundbreaking discovery has been published in the latest issue of the journal Nature.

The key to observing the single-electron carbon bond was the creation of a molecule designed to stabilize it. An international research team led by the University of Tokyo in Japan devised a molecule with a stable carbon ring "shell" that helped bring the central carbon-carbon bonds together. Unlike conventional carbon-carbon bonds, this central bond is longer, making it easier to lose an electron in oxidation reactions, thus forming the rare single-electron bond.

To capture this compound in a stable, observable form, researchers crystallized it. Under iodine conditions, oxidation reactions produced a purple salt, where the stable shell aided in maintaining the internal single-electron carbon-carbon bond. Subsequently, the researchers characterized the molecule and the carbon bond using various analytical techniques, revealing that this compound is highly stable at room temperature.