Transition Metal Catalyzed Olefin Polymerizations: Mechanistic Studies and Catalyst Design

莫里斯·布鲁克哈特博士，北卡罗来纳大学教堂山分校化学系，由化学部无机、生物无机和有机金属项目支持，并由数学和物理科学局多学科活动办公室提供仪器支持，用于后期过渡金属烯烃聚合催化剂的机理和设计研究。该项目的主要目的将是研究体积庞大的阿尔法二亚胺的镍(II)和钯(II)络合物，例如，这种络合物具有通过配体变化控制聚合物链分支的能力。将对聚合反应进行严格的机理研究，以了解控制催化剂行为和决定所得聚合物性能的因素。为了探索配体结构对聚合物微观结构的影响和单体包结的机理，将合成多种具有不同配体结构的α-二亚胺催化剂。这些催化剂将用于新单体的聚合和共聚。利用这些研究的见解，将制备包含大体积双齿阴离子配体的新的中性Ni(II)和Pd(II)催化剂体系。这些体系应该表现出很好的官能团耐受性，特别是对乙烯和极性烯烃的共聚反应是很好的催化剂。为了了解金属催化的烯烃聚合的基本方面，人们进行了大量的研究，这些研究的结果已被用于开发新的催化剂。这些都是非常重要的贡献，因为美国每年生产的聚烯烃超过300亿磅。大多数商用的烯烃聚合催化剂都是基于早期过渡金属或稀土金属。在本项目中，将研究一系列用途广泛的后过渡金属催化剂。这些将为催化剂在聚合过程中如何将烯烃相互连接以及具有潜在工业应用的新催化剂体系提供基本信息。

Dr. Maurice Brookhart, Department of Chemistry, University of North Carolina - Chapel Hill, is supported by the Inorganic, Bioinorganic, and Organometallic Program of the Chemistry Division, with a contribution for instrumentation from the Office of Multidisciplinary Activities of the Mathematical and Physical Sciences Directorate, for mechanistic and design studies of late transition metal olefin polymerization catalysts. The major thrust of the project will be the study of Ni(II) and Pd(II) complexes of bulky alpha-diimines, which have, for example, the ability to control polymer chain branching through ligand variation. Rigorous mechanistic studies of the polymerization reactions will be carried out in order to gain understanding of the factors that control the behavior of the catalysts and that determine the properties of the resultant polymer. A variety of alpha-diimine based catalysts, with a variety of ligand architectures, will be synthesized with the objective of probing the effect of ligand structure on polymer microstructure and mechanisms of monomer enchainment. These catalysts will be evaluated for the polymerization and copolymerization of new monomers. Using insights from these studies new neutral Ni(II) and Pd(II) catalyst systems will be prepared containing bulky bidentate anionic ligands. These systems should exhibit great functional group tolerance and be especially good catalysts for the copolymerization of ethylene and polar olefins. Intensive research has been directed toward understanding fundamental aspects of metal-catalyzed olefin polymerization and the results of these studies have been used to develop new catalysts. These have been enormously important contributions since over thirty billion pounds of polyolefin are produced in the United States each year. Most of the commercial olefin polymerization catalysts are based on early transition or lanthanide metals. In this project a series of highly versatile late transition metal catalysts will be investigated. These will provide fundamental information on how catalysts join olefins to one another during the polymerization process as well as new catalyst systems with potential industrial applications.