Formation of Zirconocene Fluoro Complexes: No Deactivation in the Polymerization of Olefins by the Contact‐Ion‐Pair Catalysts [Cp′₂ZrR]⁺[RB(C₆F₅)₃]⁻

Abstract

Not a catalyst killer: In the reaction of 2 with B(C6F5)3, a nucleophilic aromatic substitution with CF bond cleavage leads to the unexpected difluoride 1. Although the formation of ZrF species during olefin polymerization by [Cp′2ZrR]+[RB(C6F5)3]− (Cp′=substituted or unsubstituted η5‐cyclopentadienyl; R=Me, H) catalysts is often described as a deactivation, the catalyst precursor 2 can be regenerated from 1 through treatment with iBu2AlH.

Synthesis and reactivity of di(silylamido)cyclopentadienyl titanium and zirconium complexes

“…This is a slow reaction that takes place when the cationic complexes 30 and 32 are heated at 80°C for 7 days to give complex 34. In agreement with this proposal we never observed conversion of 34 into 33 [53].…”

Evidence of Fluoride Transfer from the Anion of [Zr{C5H3[SiMe2(η1‐NtBu)]2}]+[RB(C6F5)3]− Complexes to the Zirconocenium Cation

“…A similar fluoride transfer was reported very recently for the reaction of the dinuclear hydride complex [{rac-(ebthi)ZrH-(m-H)} 2 ] with B(C 6 F 5 ) 3 . [15] The thermal fluoride transfer observed for complexes 1 and 2 may occur by nucleophilic addition of PPh 3 to the p-C À F bond of one of the electron-deficient C 6 F 5 rings of the metal-coordinated alkylborate counteranion [RB(C 6 F 5 ) 3 ] À with immediate transfer of the generated fluoride to the zirconocenium cation to give 3.…”

Activation of Aromatic, Aliphatic, and Olefinic Carbon–Fluorine Bonds Using Cp*2HfH2

“…[10] Rosenthal et al have shown that cationic zirconocene complexes can abstract fluoride from perfluorophenyl groups to give Zr-F species. [11] In most cases where suggested, fluoride transfer is thought to likely occur through a cyclic transition state [Equation (2)]. Furthermore, olefinic fluorocarbons have been shown to participate in β-fluoride elimination following insertion into metal-hydride bonds, leading to the generation of a new fluorocarbon or small fluorine-containing molecule.…”