Building a Lewis Acidic Phosphorus

In recent years, the synthesis and structural elucidation of mononuclear main group polycations has been achieved by employing electron rich substituents. However, the majority of these polycations are either coordinatively saturated or resemble classical Lewis bases, rendering them inactive as Lewis acids. This certainly holds true with respect to the recently reported NHCstabilized dicationic (I, Figure 1) and tricationic (II, Figure 1) P(III)-centered compounds which resemble neutral Lewis basic phosphines (III, Figure 1).