C−H Activation of the Trimethylsilyl-Substituted Cyclopentadienyl Ligand in the “Cation-like” Complex [Cp‘ ‘‘2ZrMe][Me(B(C6F5)3] (Cp‘ ‘‘ = η5-C5H2-1,2,4-(SiMe3)3)

The substituted cyclopentadienyl zirconium complex [Cp‘ ‘‘ 2 ZrMe 2 ] ( 1; Cp‘ ‘‘ = η 5 -C 5 H 2 -1,2,4-(SiMe 3 ) 3 ) reacts with tris(perfluorophenyl)borane, B(C 6 F 5 ) 3, in pentane to give the two species [Cp‘ ‘‘ 2 ZrMe][MeB(C 6 F 5 ) 3 ] ( 2 ) and [Cp‘ ‘‘(η 5 -C 5 H 2 -2,4-(SiMe 3 ) 2 -1-η 1 -SiMe 2 CH 2 )Zr][MeB(C 6 F 5 ) 3 ] ( 3 ). Complex 3 was characterized by an X-ray structure determination, showing the C−H activation of a SiMe 3 group attached to the cyclopentadienyl ligand. Complexes 2 and 3 could be described, respectively, as the active and inactive species which both arise from 1 and B(C 6 F 5 ) 3 in the cationic polymerization.