Unexpected Reactions between Ziegler–Natta Catalyst Components and Structural Characterization of Resulting Intermediates

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• 作者：Piotr Sobota ; Józef Utko ; Tadeusz Lis ; Łukasz John ; Rafał Petrus ; Anna Drąg-Jarząbek
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：May 2, 2016
• 年：2016
• 卷：55
• 期：9
• 页码：4636-4642
• 全文大小：500K
• 年卷期：0
• ISSN：1520-510X

文摘

In this work, we investigated precursors and procatalysts with well-defined crystal structures and morphologies in Ziegler–Natta systems to improve our understanding of the nature of the active metal sites. Molecular cluster precursors such as [Mg₄Ti₃(μ₆-O)(μ₃-OH)₃(μ-OEt)₉(OEt)₃(EtOH)₃Cl₃], [Mg₄Ti₃(μ₆-O)(μ₃-OH)(μ₃-OEt)₂(μ-OEt)₉(OEt)₃(EtOH)₃Cl₃], and [Mg₆Ti₄(μ₆-O)₂(μ₃-OH)₄(μ-OEt)₁₄(OEt)₄(EtOH)₂Cl₂] were prepared via simple elimination of the cyclopentadienyl ring from Cp₂TiCl₂ as CpH in the presence of magnesium metal and ethanol. Titanocene dichloride acts as both a source of titanium and a magnesium-chlorinating agent. The resulting novel complexes were characterized using single-crystal X-ray diffraction. In these compounds, Ti(OEt)₄ molecules are grafted onto Mg₄ and Mg₆ ethoxide cubane-like surfaces; this strongly affects the procatalyst morphology, which is transferred to the polymer. Mg₄(OR)₈ units act as carriers for the AlR₃ co-catalyst, resulting in return of alkyl functions to the Ti center.