Behold the single-electron carbon-carbon bond

Chemists at Hokkaido University have experimentally confirmed the existence of a single-electron carbon-carbon bond for the first time ( Nature 2024, DOI: 10.1038/s41586-024-07965-1 ). Linus Pauling proposed the concept of one-electron covalent bonds in 1931, but direct evidence of their existence in carbon systems had proved elusive. Single-electron C–C bonds have particularly low bond strengths and are consequently highly reactive, which makes them difficult to isolate and study. But electron-rich alkanes such as hexaphenylethane (HPE) derivatives are promising substrates to probe this phenomenon, as their adjacent π systems should stabilise the electron-deficient radical cation product. But actually accessing the transient one-electron state is itself a challenge, because HPEs typically undergo two-electron oxidation, breaking the C–C bond to form a pair of cations. Takuya Shimajiri , who is now at the University of Tokyo, and colleagues hoped to influence this redox chemistry using structural modifications. The team started with a highly