Sulfur hexafluoride (SF₆) is fairly inert, which makes it useful for different applications, e.g, as an electrical insulator. However, it also is a potent greenhouse gas with a very long lifetime in the atmosphere. Thus, methods for its degradation are interesting research targets—in particular, catalytic approaches.

Josep Cornella, May Planck Institute for Coal Research, Mülheim an der Ruhr, Germany, and colleagues have found that certain pincer bismuthinidene complexes can degrade both SF₆ and the related compound PhSF₅. The team first reacted a symmetric N,C,N-bismuthnidene featuring two tert-butyl substituents with SF₆ in the presence of lithium triflate. This led to new bismuth species, a Bi(II) dimer formed from the pincer complex and a sulfide-bridged Bi(III) dimer. Thus, the pincer complex can activate SF₆. A reaction of the same pincer complex with PhSF₅ gave a new bismuth(III) thiophenolate species.

The researchers then switched to a bismuthinidene with an asymmetric pincer ligand (pictured), in which one imine unit was replaced with a dimethyl-substituted amine. This species was able to catalytically degrade both SF₆ and PhSF₅ in the presence of PMe₃ as a reducing agent, giving S=PMe₃ and F₂PMe₃ or PhSH and O=PMe₃, respectively. According to the researchers, this represents the first example of the catalytic degradation of PhSF₅.

• Activation and Catalytic Degradation of SF₆ and PhSF₅ at a Bismuth Center,
  Vanessa A. Béland, Nils Nöthling, Markus Leutzsch, Josep Cornella,
  J. Am. Chem. Soc. 2024.
  https://doi.org/10.1021/jacs.4c07044