abstracts - Институт катализа им. Г.К. Борескова

KS-II-6KEY INTERMEDIATES OF METALLOCENES AND POST-METALLOCENESCATALYZED OLEFIN POLYMERIZATIONTalsi E.P., Bryliakov K.P., Bochmann M. 1 , Semikolenova N.V., Zakharov V.A.Boreskov Institute of Catalysis SB RAS, Novosibirsk, Russia1 University of East Anglia, Norwich, United KingdomE-mail: talsi@catalysis.ruMethylaluminoxane (MAO) remains the most widely used co-catalyst for metallocene andpost-metallocene based catalysts. Information on the structure of “cation-like” species formedupon activation of these catalysts with MAO is crucial in the understanding of polymerizationactivities. We present here the 1 H and 13 C NMR spectroscopic study of the cationicintermediates formed upon activation of various metallocene and post-metallocene catalystswith MAO. The following metallocene catalysts have been investigated: (Cp-R) 2 ZrCl 2 (R= H,Me, 1,2-Me 2 , 1,2,3-Me 3 , 1,2,4-Me 3 , Me 4 , Me 5 , nBu, tBu), rac-C 2 H 4 (Ind) 2 ZrCl 2 ,rac-Me 2 Si(Ind) 2 ZrCl 2 , rac-Me 2 Si(1-Ind-2-Me) 2 ZrCl 2, rac-Me 2 Si(2-Me-Benzind) 2 ZrCl 2 ,rac-Me 2 Si(1-Ind-2-Me-4-Ph) 2 ZrCl 2, rac-C 2 H 4 (1-Ind-4,5,6,7-H 4 ) 2 ZrCl 2 , (1-Ind-2-Me) 2 ZrCl 2 ,Me 2 C(Cp)(Flu)ZrCl 2 , Me 2 C(Cp-3-Me)(Flu)ZrCl 2 , Me 2 Si(Flu) 2 ZrCl 2 , Si 2 Me 4 (2-Ind)ZrCl 2 ,Si 2 Me 4 (2-Ind-4,5,6,7-H 4 ) 2 ZrCl 2 , Cp 2 TiCl 2 , rac-C 2 H 4 (Ind) 2 TiCl 2 , rac-Me 2 Si(2-Me-Benzind) 2 TiCl 2 , (C 5 Me 5 )TiCl 3 and [(Me 4 C 5 )SiMe 2 N t Bu]TiCl 2 . It has been found that inconditions approaching to real polymerization (Al/Zr or Al/Ti > 200), intermediates [L 2 M(μ-Me) 2 AlMe 2 ] + [Me-MAO] − (III) and L 2 MMe (+) ←Me−Al (-) ≡MAO (IV) (M = Zr or Ti) arepresent in the reaction solution. For the more restricted coordination gap aperturemetallocenes, heterobinuclear ion pairs of type III strongly dominate in the reaction solution,whereas in the more open half-sandwich, disilyl bridged and constrained-geometrycomplexes, a closer approach of [Me-MAO] - is favored to give mainly ‘zwitterion-like’species of type IV upon activation with MAO._+MAOMe Me _MeAlTiAl MeMAO+Me MeTiMeIIIEthene polymerization activity strongly depends on the Al/Zr ratio (Al/Zr = 200-1000) for thesystems (Cp-R) 2 ZrCl 2 /MAO (R = H, Me, nBu, tBu), while it changes insignificantly in thesame range of Al/Zr ratios for the catalytic systems (Cp-R) 2 ZrCl 2 /MAO (R = 1,2-Me 2 , 1,2,3-48IV