Science sees miracle as first-ever single electron carbon bond spotted

About 90 years ago, American chemical engineer Linus Pauling proposed a unique concept. He suggested that two atoms don’t necessarily require two or more electrons to form a bond, one electron covalent bond can also exist.

Back then Pauling didn’t have access to the tools required to observe such bonds. His theory was proven right in 1998 when scientists discovered a single electron bond in phosphorus for the first time.

Since then such bonds have also been detected in hydrogen and other elements , but no scientists ever came across a single electron carbon-carbon bond.

However, for the first time, a team of researchers from Japan’s Hokkaido University has identified a single electron covalent bond between two carbon atoms. Some experts see this discovery as miracle.

Isolating a single electron carbon bond

Two carbon atoms tend to form bonds with two electrons sharing. Single electron covalent bonds are highly reactive and less stable as they have low bond strength. All these factors make it very tricky to isolate carbon atoms bonded via a single electron.

This is why, “Although several pioneering studies have reported one-electron bonds between heteroatoms, direct evidence for one-electron bonds between carbon atoms remains elusive,” the study authors note .

The only possible way to do this is to create a compound that could stabilize the bond. To achieve this, the study authors performed an oxidation reaction of a derivative of hexaphenylethane using iodine. This derivative contained a very elongated paired-electron covalent bond between two carbon atoms.

The reaction resulted in the formation of violet-colored crystals. When the researchers used X-ray diffraction to examine the crystals, they noticed that the two elongated carbon atoms had come closer due to the formation of a single-electron covalent between them.

These results were further checked using Raman spectroscopy, a method used to study the molecular makeup and arrangement of materials. The results of this analysis confirmed the presence of the single electron C-C bond.

“These results thus constitute the first piece of experimental evidence for a carbon-carbon single-electron covalent bond, which can be expected to pave the way for further developments of the chemistry of this scarcely-explored type of bonding,” Takuya Shimajiri, first author of the study and an assistant professor at Tokyo University, said .

The significance of this discovery

Carbon is the essential ingredient for life and most of the things that support life on Earth. From the cells in your body to the car you drive, and the food you eat, nearly everything you see and use is made of carbon.

The current finding holds importance as “elucidating the nature of single-electron sigma-bonds between two carbon atoms is essential to gain a deeper understanding of chemical-bonding theories and would provide further insights into chemical reactions,” Yusuke Ishigaki, one of the study authors and a professor at Hokkaido University, said.

However, the study authors aren’t sure whether their research could result in some practical applications, but they do suggest that “it will be in the textbooks.”

The study is published in the journal Nature .