Intramolecular Ion-Ion Interactions in Zwitterionic Metallocene Olefin Polymerization Catalysts Derived from 'Tucked-In' Catalyst Precursors and the Highly Electrophilic Boranes XB(C_6F_5)_2 (X = H, C_6F_5)

摘要

The reactions of so called :tuck-in" permethyl zirconocene compounds Cp~*(η~5-η~1-C_5Me_4CH_2)ZrX(X= Cl (1a), C_6H_5 (1b), CH_3 (1c)) with the highly electrophilic boranes HB(C_6F_5)_2 and B(C_6F_5)_3 are described. The products are zwitterionic olefin polymerization catalysts. Reactions with 1a and 1b yielded single products cleanly, but reactions with tuck-in methyl starting material 1c gave mixtures. Spectroscopic and structural studies showed that the electrophilic zirconium center in the product zwitterions was stabilized by a variety of mechanisms.