Group 4 Metal Complexes of Boron Heterocycles

阿瑟·J·阿什博士，III，密歇根大学化学系，由化学部无机、生物无机和有机金属计划支持，用于研究涉及第13和15族元素的杂环化合物及其过渡金属络合物。以往的研究表明，硼苯锆络合物可以作为烯烃聚合的均相催化剂。在这一结果的基础上，通过类比已知的活性催化剂反式茂金属，将设计一系列含有杂芳烃配体的金属络合物，以获得高活性和立体专一性的烯烃聚合催化剂。具体地说，将制备具有不同电子和空间需求的侧基的硼苯络合物和一系列桥联的硼苯络合物。这些化合物将利用杂芳族配体可能存在的给电子能力的变化来微调和开发更有效的聚合催化剂。最后，将制备新的含硼杂环化合物，以扩大可用作配体的杂环化合物的范围。过渡金属络合物促进有机化合物非常选择性的催化和化学计量转化。金属中心的许多独特的反应性反映了金属周围的电子密度，这种电子密度可以通过调节连接到金属上的基团来控制。一个非常常见的‘基团’包含一个碳氢单元环，这种环被称为‘芳香族’排列。在这个项目中，将制备一系列金属络合物，其中一个由碳、氢和硼物种组成的‘芳香’基团连接到金属上。这将允许仔细调整金属的电子密度，以促进特定的化学和催化行为，并将为了解现有工艺和合理设计新工艺奠定基础。

Dr. Arthur J. Ashe, III, Department of Chemistry, University of Michigan, is supported by the Inorganic, Bioinorganic, and Organometallic Program of the Chemistry Division for the study of heteroaromatic compounds involving group 13 and 15 elements and their transition metal complexes. Previous research has demonstrated that boratabenzene zirconium complexes can serve as homogeneous catalysts for the polymerization of olefins. Building on this result and by analogy to ansametallocenes that are known to be active catalysts, a series of metal complexes containing heteroaromatic ligands will be designed with the goal of obtaining highly active and stereospecific olefin polymerization catalysts. Specifically boratabenzene complexes which bear pendant substituents of varying electronic and steric demand and a series of bridged boratabenzene complexes will be prepared. These compounds will exploit variations in electron donating ability possible with the heteroaromatic ligands to fine tuning and develop more effective polymerization catalysts. Finally new boron containing heterocycles will be prepared in order to extend the range of heteroaromatic compounds available to be used as ligands. Transition metal complexes promote very selective catalytic and stoichiometric transformations of organic compounds. Much of the unique reactivity at the metal center is a reflection of the density of electrons surrounding the metal and this electron density can be controlled by adjusting the groups that are attached to the metal. A very common 'group' contains a ring of carbon-hydrogen units in what is called an 'aromatic' arrangement. In this project a series of metal complexes will be prepared in which an 'aromatic' group composed of carbon-hydrogen and boron species is attached to a metal. This will permit the electron density about the metal to be carefully adjusted in order to promote specific chemical and catalytic behavior and will set the ground work both to understand existing processes and to rationally design new ones.