Journal of the American Chemical Society, Vol.132, No.2, 452-452, 2010
Reactive Intermediates Formed During Olefin Polymerization by Methylalumoxane-Activated ansa-Zirconocene Catalysts: Identification of a Chain-Carrying Intermediate by NMR Methods
Addition of 1-hexene to methylalumoxane-activated catalyst systems based on rac-Me2Si(ind)(2)ZrMe2 causes, concurrent with polyhexene formation and diminution of the otherwise prevalent cation [rac-Me2Si(ind)(2)-Zr(mu-Me)(2)AlMe2](+), formation of a hitherto unobserved species [rac-Me2Si(ind)(2)Zr(mu-R)(mu-Me)AlMe2](+), where R is a Zr-bound polyhexyl chain. As hexene is increasingly consumed, this cation decays, mainly back to [rac-Me2Si(ind)(2)Zr(mu-Me)(2)AlMe2](+) and, in part, to some species containing a Zr-bound allylic chain end.