Calculations suggest that a new kind of chemical bond proposed in the 1980s might have occurred in a 2012 experiment that coupled two bromine atoms to an exotic form of hydrogen.

The molecule BrHBr is held together by weak electrostatic attractions known as Van der Waals' forces. Jörn Manz at Shanxi University in Taiyuan, China, and his colleagues calculated what would happen if the hydrogen were swapped for a lighter isotope called muonium, in which a positively charged elementary particle called an antimuon takes the place of the proton.

They predict that the BrMuBr molecule would be held together not by electrostatic forces but with a vibrational bond. The muonium shuttling between the bromine atoms would form a lower-energy system than the vibrations of MuBr alone.

These calculations suggest that the bond might have been produced in the earlier experiment, which combined muonium and bromine.

Angew. Chem. Int. Ed. http://doi.org/f2vjn6 (2014)