Nucleophilic Activation of Sulfur Hexafluoride: Metal-Free, Selective Degradation by Phosphines

The development of new methods for the chemical activation of the extremely inert greenhouse gas sulfur hexafluoride (SF₆ ) not only is of current environmental interest, but also offers new opportunities for applications of SF₆ as a reagent in organic synthesis. We herein report the first nucleophilic activation of SF₆ by Lewis bases, namely by phosphines, which results either in its complete degradation to phosphine sulfides and difluorophosphoranes or in the selective conversion of SF₆ into a bench-stable, crystalline salt containing the SF₅^- anion. Quantum chemical calculations reveal a nucleophilic substitution mechanism (S_N 2) for the initial fluorine abstraction from SF₆ by the phosphine. Furthermore, a scalable one-pot procedure for the complete decomposition of SF₆ into solid, nonvolatile products is presented based on cheap and commercially available starting materials.