Bis(Pentafluorophenyl) (2-perfluorobiphenylyl)borane. A new perfluoroarylborane cocatalyst for single-site olefin polymerization

Bis(pentafluorophenyl)(2-perfluorobiphenylyl)borane, (C₆F₅)₂B(C₁₂F₉) (BPB), has been synthesized and characterized to serve as a new strong organo-Lewis acid cocatalyst for single-site olefin polymerization. BPB efficiently activates a variety of group 4 dimethyl complexes to form highly active homogeneous Ziegler-Natta olefin polymerization catalysts. Reaction of BPB with Cp₂ZrMe₂, rac-Me₂Si(Ind)₂ZrMe₂) and (CGC)MMe₂ (M = Zr, Ti; CGC = Me₂Si(n⁵Me₄C₅)(^tBuN)) (1:1 molar ratio) rapidly and cleanly produces the base-free cationic complexes Cp₂ZrMe⁺[MeB(C₁₂F₉)(C ₆F₅)₂]^- (1), rac-Me₂Si(Ind)₂ZrMe⁺[MeB(C₁₂F ₉)(C₆F₅)₂]^- (2), and (CGC)MMe⁺[MeB(C₁₂F₉)(C₆F ₅)₂]^- (M = Zr, 3; M = Ti, 4), respectively. These complexes have been characterized by NMR and elemental analysis and are shown to be competent for ethylene and propylene polymerization. In general, BPB-derived catalysts exhibit polymerization activities comparable to or higher than those of the B(C₆F₅)₃-derived analogues, with the products exhibiting higher molecular weights but comparable polydispersities, polypropylene isotacticities, and, for ethylene + 1-hexene, comonomer incorporation.