Boranes, perfluorinated

At the end of considerations of the role of alkylaluminoxanes as activators for metallocenes as Ziegler-Natta olefin polymerisation catalysts, it should be noted that the analogy between methylaluminoxane and simple acidic moieties does not appear to hold. For example, highly Lewis acidic perfluorinated boranes, such as Bf CgFs, show enhanced activity as activators when compared with [Al(Me)0]x, but the stability of the resulting zirconocene-based catalyst is drastically lower than that of the catalyst formed with [Al(Me)0]x [98]. 

The first polymer containing fluorinated arylborane substituents has recently been reported. The highly functionalized soluble polymer (195) was obtained in good yield by treatment of poly(4-dibromoborylstyrene) with equimolar amounts of pentafluorophenylcopper at low temperature. Polymer (195) shows a slightly lower Lewis acidity than the perfluorinated borane B(C6F5)3 as determined by complex-ation with crotonaldehyde (equation 41). However, in this... 

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