Reactions of Bis(pentafluorophenyl)borane with Phosphine Olefin Complexes of Zirconocene

Zirconocene olefin complexes Cp₂Zr(PPh₂Me)(η²-RCHCH₂) (R = H, Et, Ph) react rapidly with 2 equiv of [HB(C₆F₅)₂]_n to give the zwitterionic products Cp₂Zr{η³-[CH(R)CH₂BH(C₆F₅)₂]} (R = H (2a), Et (2b), Ph (2c)) and the borane−phosphine adduct Ph₂MeP· HB(C₆F₅)₂. Spectroscopic and structural evidence confirms an interaction between zirconium and the β-carbon attached to boron, resulting in pentacoordinated carbon.