Reactive Cationic Zr(IV) and Ti(IV) Complexes Containing Labile Ligands

Ziegler-Natta催化剂作为工业催化剂被广泛使用 用于聚合物的合成。 锆和钛 本项目将研究的化合物与 可溶性齐格勒-纳塔催化剂。 该项目预计将 更好地了解这些催化剂的功能 并提供所需的信息，以设计更具体和 更有效的聚合物合成催化剂。 合成和分离阳离子表面活性剂的一般方法 bis-Cp-Zr（R）（L）型有机锆络合物，其中L 是一种不稳定的配体 有机锆 络合物具有高活性。 它们的Zr-R键经历快速的 酮、腈和其它极性不饱和的插入 底物，和THF络合物中的乙烯 不存在A1助催化剂。 这些观察结果支持了最近 提出了阳离子钛、锆配合物是活性物种的观点 在可溶性齐格勒-纳塔催化剂体系中。 阳离子 有机锆络合物也容易氢化， 合成有用的阳离子染料。 研究计划是综合一系列广泛的 Cp_2M（R）（L）配合物（M = Ti，Zr）的研究 它们与烯烃和其他 不饱和底物和氢。 这些新颖 化合物提供了一个机会，研究基本的 研究了M-R键（M = Ti，Zr）在Ti，Zr中的插入反应特征， 没有A1助催化剂引起的许多并发症。 该项目还包括研究开发不对称 基于手性阳离子Cp 2 M（R）（L）配合物的有机合成。

Ziegler-Natta catalysts are used widely as industrial catalysts for the synthesis of polymers. The zirconium and titanium compounds which will be studied in this project are related to soluble Ziegler-Natta catalysts. This project is expected to provide a better understanding of how these catalysts function and to provide information needed to design more specific and more efficient catalysts for polymer synthesis. General methods for the synthesis and isolation of cationic organozirconium complexes of the type bis-Cp-Zr(R)(L) where L is a labile ligand have been discovered. The organozirconium complexes are highly reactive. Their Zr-R bonds undergo rapid insertion of ketones, nitriles and other polar unsaturated substrates, and the THF complexes polymerize ethylene in the absence of an A1 cocatalyst. These observations support recent proposals that cationic Ti and Zr complexes are active species in soluble Ziegler-Natta catalyst systems. The cationic organozirconium complexes are also easily hydrogenated to synthetically useful cationic hydrides. The research plan is to synthesize an extensive series of Cp2M(R)(L) complexes (M = Ti, Zr) and to study the scope and mechanisms of their reactions with olefins and other unsaturated substrates, and with hydrogen. These novel compounds provide an opportunity to study the fundamental features of insertion reactions of M-R bonds (M = Ti, Zr) in the absence of the many complications caused by A1 cocatalysts. Also included in this project is research to develop asymmetric organic syntheses based on chiral cationic Cp2M(R)(L) complexes.