Aldiminium Cations as Countercations to Discrete Main Group Fluoroanions

The reactions of group 14 tetrafluorides (SiF₄, GeF₄, and SnF₄) and group 15 pentafluorides (PF₅, AsF₅, and SbF₅) with the CAAC-based trifluoride reagent [^MeCAACH][F(HF)₂] led to the isolation of salts containing discrete 5- or 6-coordinated fluoroanions. The syntheses of [^MeCAACH][SiF₅], [^MeCAACH][GeF₅], [^MeCAACH][(THF)SnF₅], and the structurally related [^MeCAACH][(dioxane)SnF₅], [^MeCAACH][PF₆], [^MeCAACH][AsF₆], and [^MeCAACH][SbF₆] are effective, selective and in high yield. All compounds were characterized by X-ray single-crystal structure analysis, NMR and Raman spectroscopy. It is worth noting that the synthesized [^MeCAACH][GeF₅] is a rare example of a structurally characterized compound with discrete [GeF₅]^- anion, while [^MeCAACH][(THF)SnF₅] and [^MeCAACH][(dioxane)SnF₅] represent the first compounds with discrete octahedrally coordinated tin fluoride anions with incorporated solvent molecules. Finally, the aldiminium-based cation [^MeCAACH]⁺ proved to be suitable for the stabilization of rare discrete main group fluoride anions.