Synthesis, Structure, and Reactivity of (C5H4SiMe3)2Y{(μ-FC6F4)(μ-Me)B(C6F5)2}:  Tight Ion Pairing in a Cationic Lanthanide Complex

The reaction of [Cp‘2YMe]2 (Cp‘ = C5H5, C5H4SiMe3) with B(C6F5)3 affords the complexes Cp‘2Y{MeB(C6F5)3}. The anion is coordinated in a chelating fashion via one ortho-fluorine atom and agostic interactions to two of the methyl hydrogens; the complexes are highly fluxional in solution. They act as initiators for the carbocationic polymerization of isobutene.