Superhalogens as Building Blocks of Super Lewis Acids.

Lewis acids play an important role in synthetic chemistry. Using first-principle calculations on some newly designed molecules containing boron and organic heterocyclic superhalogen ligands, we show that the acid strength depends on the charge of the central atom as well as on the ligands attached to it. In particular, the strength of the Lewis acid increases with increasing electron withdrawing power of the ligand. With this insight, we highlight the importance of superhalogen-based ligands in the design of strong Lewis acids. Calculated fluoride ion affinity (FIA) values of B[C2 BNO(CN)3 ]3 and B[C2 BNS(CN)3 ]3 show that these are super Lewis acids.