Synthesis, Structures, and Olefin Polymerization Characteristics of Group 4 Catalysts [Zr{(OAr)2py}Cl2(D)] (D = O-Donors, Cl[HPR3]) Supported by Tridentate Pyridine-2,

详细信息    查看全文

• 作者：Michael C. W. Chan ; Ka-Ho Tam ; Nianyong Zhu ; Pauline Chiu ; and Shigekazu Matsui
• 刊名：Organometallics
• 出版年：2006
• 出版时间：January 30, 2006
• 年：2006
• 卷：25
• 期：3
• 页码：785 - 792
• 全文大小：178K
• 年卷期：v.25,no.3(January 30, 2006)
• ISSN：1520-6041

文摘

The Zr(IV) complexes [Zr(L¹)X₂(D)] [H₂L¹ = 2,6-di(3-tert-butyl-5-methylphen-2-ol)pyridine; X =Cl, D = thf (1), OEt₂ (2), acetophenone (3), benzophenone (4), 2-acetonaphthone (5), Cl[HPR₃] {R =Me (6), Et (7); R₃ = Me₂Ph (8)}; X = CH₂Ph (9)] have been synthesized, and the crystal structures of3, 4, and 7 have been determined. These catalysts, assisted by the robustness and chelating strength ofthe pyridine-bis(phenolate) moiety, exhibit excellent activities for ethylene polymerization in conjunctionwith MAO. Studies to assess the impact of the donor group during the catalytic process suggest that thesame active species is generated by 1-8/MAO and the donor group does not play an active role. Evenhigher activities are observed for the 1/ⁱBu₃Al/Ph₃CB(C₆F₅)₄ system in ethylene polymerization andpropylene copolymerization reactions (36 590 and 15 700 g of polymer (mmol of catalyst)^-1 h^-1,respectively), with the latter displaying good C3 incorporation (25.4 mol % C3). Insight into the catalyticbehavior of the 1/MAO system has been derived from GPC and NMR characterization of the polymersprepared under different reaction conditions. ¹H and ¹³C NMR end-group analyses reveal resonances forsaturated methyl chain-end groups only and undetectable or negligible levels of unsaturated vinyl chainends. This indicates that for the polymerization chain-transfer mechanism, the conventional -H transferreactions to the metal/monomer are insignificant and the unusual chain transfer to Al pathway is vastlydominant.