Binuclear Heteroligated Titanium Catalyst Based on Phenoxyimine Ligands: Synthesis, Characterization, and Ethylene (Co)polymerization

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• 作者：Shuliang Han ; Erdong Yao ; Wei Qin ; Shaofei Zhang ; Yuguo Ma
• 刊名：Macromolecules
• 出版年：2012
• 出版时间：May 22, 2012
• 年：2012
• 卷：45
• 期：10
• 页码：4054-4059
• 全文大小：312K
• 年卷期：v.45,no.10(May 22, 2012)
• ISSN：1520-5835

文摘

A binuclear heteroligated titanium(IV) catalyst based on phenoxyimine ligands (FI²-Ti₂) with its crystal structure elucidated has been developed for the first time for olefin (co)polymerization. In ethylene polymerization, the activity of the binuclear catalyst FI²-Ti₂ can reach 3.0 脳 10⁶ g mol^鈥? h^鈥?, and the polydispersity of the resulting polymers is narrow. In copolymerization of ethylene and other olefins, similar incorporation ratios for monoenes are obtained for FI²-Ti₂ and FI-Ti₁. However, the incorporation ratio of 1,5-hexadiene increases from 3.2% using FI-Ti₁ to 8.8% with FI²-Ti₂. In comparison, the binuclear monophenoxyimine catalyst, [FI²-Ti₂(THF)₂], exhibits higher catalytic activity and incorporates more 伪-olefins than its mononuclear analogue [FI-Ti₁(THF)] in the copolymerization. These results are interpreted as consequences of two effects. First, the cooperativity between the two metal centers facilitates the coordination of olefin. Second, the substitutions near the active sites exert a steric effect by blocking and suppressing the binding of comonomers.