马欧的分子表亲的作用机制
Gaia Urciuoli1,2,3, Francesco Zaccaria1,3, Cristiano Zuccaccia2,3
1Department of Chemical Sciences, Federico II University of Naples, Napoli 80126, Italy.
-基酸盐 (AAB) 盐AlHAl_DMA激活了烯聚合催化剂并清除了杂质. 它的明确结构揭示了化物抽取和化物交换的机制,产生活跃的Zr-H物种.
科学领域:
- 有机金属化学 有机金属化学
- 聚合催化法 聚合催化法
- 材料科学 材料科学 材料科学
背景情况:
- 甲基氨酸 (MAO) 是烯聚合中广泛使用的共催化剂,但缺乏明确的分子结构.
- -基酸盐 (AAB) 盐,AlHAl_DMA,为MAO提供了一个明确的分子替代品,用于催化剂激活和杂质清理.
- 了解AlHAl_DMA作为共催化剂的机制对于优化烯聚合过程至关重要.
研究的目的:
- 研究-基酸盐 (AAB) 盐AlHAl_DMA作为olefin聚合中的共催化剂的作用机制.
- 阐明AlHAl_DMA在从前催化剂中提取化物和生成活性催化物种中的作用.
- 探索AlHAl_DMA的清除杂质的特性,特别是其μ-H片段的作用.
主要方法:
- 前催化剂 (Me2SiCp2) -ZrCl2与AlHAl_DMA和一个模型物种[AliBu2(L) ]+的反应.
- 反应中间体的分离和表征,包括Zr-(μ-Cl) -Al异核添加物和多核Zr/Al添加物与桥接μ-Cl和μ-H片段.
- 深度2DNMR光谱和单晶X射线衍射用于介质和产品的结构阐明.
主要成果:
- 一种罕见的Zr-(μ-Cl) -Al异质核添加物的分离 (2),在化物抽取中是一种合理的中间体.
- 在将DIBAL-H添加到中间体2后,形成多核Zr/Al添加物 (3-6),表明化物/化物交换.
- 通过X射线衍射测定[(Me2SiCp2) -Zr]2 ((μ-H) - ((μ-Cl) - ((μ2-iBu2AlH2) (5) 的结构性确定.
- 证据表明,AlHAl_DMA中的μ-H片段有助于其与大气中的氧气和水分快速反应,增强了杂质清理.
结论:
- AlHAl_DMA通过促进化物抽取和化物交换,产生聚合活性Zr-H物种,起到协催化剂的作用.
- AlHAl_DMA的明确结构允许进行机械研究,提供了对催化剂激活途径的见解.
- 在AlHAl_DMA中的μ-H片段是其高效的杂质清理能力的关键,超过了Al-iBu部分.
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