Alkene polymerization by a cationic zirconium diamide complex formed by ligand cyclometallation

Reaction of {(Me(3)Si)(2)N}Zr-2(CH(2)Ph)(2) 1 with B(C6F5)(3) gives a cationic benzyl complex, which at -25 degrees C, expels toluene to afford {(Me(3)Si)(2)N}Zr(CH(2)SiMe(2)NSiMe(3)){eta(n)-PhCH(2)B(C6F5)(3)} 2; strong anion coordination to zirconium in cyclometallation product 2 suppresses alkene polymerization, whereas the analogous cationic NMe(2)Ph adduct 3, formed by protonolysis of 1, polymerizes both ethene and propene.