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.