Tris(ortho‐carboranyl)borane: An Isolable, Halogen‐Free, Lewis Superacid

The synthesis of tris(ortho‐carboranyl)borane (BoCb(3)), a single site neutral Lewis superacid, in one pot from commercially available materials is achieved. The high fluoride ion affinity (FIA) confirms its classification as a Lewis superacid and the Gutmann‐Beckett method as well as adducts with Lewis bases indicate stronger Lewis acidity over the widely used fluorinated aryl boranes. The electron withdrawing effect of ortho‐carborane and lack of pi‐delocalization of the LUMO rationalize the unusually high Lewis acidity. Catalytic studies indicate that BoCb(3) is a superior catalyst for promoting C−F bond functionalization reactions than tris(pentafluorophenyl)borane [B(C(6)F(5))(3)].