Fluorine-studded cube ensnares electron

Chemists have synthesized perfluorocubane for the first time. The molecule, C₈F₈, consists of a cube of carbon atoms with fluorine atoms attached to each of its eight vertices. The synthetic feat advances fundamental fluorocarbon science, says the University of Tokyo’s Midori Akiyama, who led the research. Akiyama adds that C₈F₈ could have applications in electronic and spintronic materials.

Perfluorocubane has long interested chemists, “not only for its beautiful structure, but also for its electron acceptivity and intermolecular interactions,” Akiyama says in an email.

Her team synthesized perfluorocubane using fluorine gas in a fluorinated solvent to add seven fluorines to a cubane that had a partially fluorinated ester at one of its corners. The chemists then swapped in a different ester and converted the molecule to heptafluorocubane. Finally, they replaced the heptafluorocubane’s lone hydrogen with a fluorine.

Akiyama’s team also showed that the position of C₈F₈’s C–F antibonding orbitals allows the molecule to hold an electron inside the cube, generating a radical anion that ultimately decomposes. Capturing an electron this way contrasts with common π-conjugated electron acceptors, which hold electrons on their surfaces (Science 2022, DOI: 10.1126/science.abq0516).

Karl K. Irikura, a theorist at the US National Institute of Standards and Technology, has studied the electronic properties of perfluorocubane. “It’s exciting to see these molecules created in the real world, and not only studied by theory,” he says in an email.