Taming the Lewis Superacidity of Non-Planar Boranes: C-H Bond Activation and Non-Classical Binding Modes at Boron

The rational design of a geometrically constrained boron Lewis superacid featuring exceptional structure and reactivity is disclosed. It enabled the formation of non-classical electron deficient B-H-B type of bonding, which was supported by spectroscopic and structural parameters as well as computational studies. Taming the pyramidal Lewis acid electrophilicity through weak coordinating anion dissociation enabled a series of highly challenging chemical transformations, such as Csp² -H and Csp³ -H activation under a frustrated Lewis pair regime and the cleavage of Csp³ -Si bonds. The demonstration of such rich chemical behaviour and flexibility on a single molecular compound makes it a unique mediator of chemical transformations generally restricted to transition metals.