Borane to Boryl Hydride to Borylene Dihydride: Explicit Demonstration of Boron-to-Metal α-Hydride Migration in Aminoborane Activation

The sequence of fundamental steps implicit in the conversion of a dihydroborane to a metal borylene complex have been elucidated for an [Ir(PMe3)(3)] system. B-H oxidative addition has been applied for the first time to an aminodihydroborane, H2BNR2, leading to the generation of a rare example of a primary boryl complex, L-n(H)M{B(H)NR2}; subsequent conversion to a borylene dihydride proceeds via a novel B-to-M alpha-hydride migration. The latter step is unprecedented for group 13 ligand systems, and is remarkable in offering alpha-substituent migration from a Lewis acidic center as a route to a two-coordinate ligand system.