Unravelling the Origins of Hydroboration Chemoselectivity Inversion Using an N,O-Chelated Ir(I) Complex: A Computational Study

It has been widely reported that the transition metal catalysts can invert the chemoselectivity of hydroboration of multifunctional substrates, but the fundamental reasons for this inversion have rarely been studied. In this work, mechanistic details and chemoselectivity of the hydroboration of various E–C (E = CH, CH2, O, N, etc.) multiple bonds has been explored through density functional theory calculations, including reactions using free HBCy2 or captured HBCy2 by an N,O-chelated Ir(I) complex which includes a phosphoamidate group. The computational results demonstrate the formation of a 3-center π complex before the 4-center transition state when using free HBCy2. When the Ir(I) complex is added, the HBCy2 would be captured to form a metallaheterocyclic Shimoi-type intermediate in which a δ-[M]…H–B agostic interaction appears. Afterwards, the E–C functional group goes to intersect this hemilabile interaction rather than the P=O…B coordination bond, and the following hydride transfer is figured out to...