COMPARATIVE PHOTO-INDUCED OXIDATIVE ADDITION OF B-H, C-H, Si-H AND B-B BONDS

B-H、C-H、Si-H 和 B-B 键的比较光诱导氧化加成

基本信息

批准号：
EP/F037740/1
负责人：
Robin Perutz
金额：
$ 65.71万
依托单位：
University of York
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2008
资助国家：
英国
起止时间：
2008 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FF037740%2F1
关键词：
COMPARATIVE PHOTO INDUCED OXIDATIVE ADDITION

项目摘要

A knowledge of reaction mechanisms is what enables chemists to predict the outcome of new reactions and work out how to make new compounds most effectively. Transition-metal compounds containing metals such as rhodium and ruthenium are used extensively as catalysts for organic and industrial processes. Oxidative addition reactions form a well-known class of reactions of such catalysts. There are two major developments in oxidative addition reactions that this project addresses: (1) the development of catalytic reactions of the simplest hydrocarbons (e.g. benzene or pentane) with boron compounds that yield very useful products for further reactions (2) the realisation that oxidative addition reactions sometimes proceed via non-classical intermediates called sigma complexes ; for instance, a silane may bind to the metal without breaking the silicon-hydrogen bond in the intermediate sigma-complex, although it is completely broken in the product. Firstly, in proof of principle experiments, we have demonstrated that we can make rhodium compounds that contain right-handed ligands. We can then obtain oxidative addition products that have metal centres that are either right-handed or left-handed and can monitor exchange of these two isomers. This exchange process tells us about the existence of intermediates (or transition states) with a mirror plane. With the help of theory and experiment we can infer the existence of sigma complexes. Secondly, this proposal addresses the question of what is special about boron by measuring the rates of reaction of carefully selected transition metal compounds with the boron compounds using a short light pulse to initiate the reactions. The results will be interpreted with the aid of theoretical calculations carried out in collaboration with Eisenstein, a well-known theorist. Thirdly, we will use NMR spectroscopy to determine the distribution of products when different combinations of reagents are in competition, for instance allowing silicon and boron compounds to compete for the same transition metal species. Finally, we will investigate transition metal complexes that are claimed to be suitable for two oxidative addition reactions in succession. These precursor complexes react on irradiation of light and it would be especially interesting for applications if they can be initiated with visible light rather than ultra-violet light. Overall, this study will give us a detailed picture of the relationships between different types of oxidative addition reactions that can be fed into catalyst design.

了解反应机制使化学家能够预测新反应的结果并找出最有效地制造新化合物的方法。含有铑和钌等金属的过渡金属化合物广泛用作有机和工业过程的催化剂。氧化加成反应形成此类催化剂的一类众所周知的反应。该项目重点关注氧化加成反应的两个主要进展：(1) 开发最简单的碳氢化合物（例如苯或戊烷）与硼化合物的催化反应，产生对进一步反应非常有用的产物 (2) 实现氧化加成反应加成反应有时通过称为西格玛络合物的非经典中间体进行；例如，硅烷可以与金属结合，而不会破坏中间σ络合物中的硅氢键，尽管它在产品中完全断裂。首先，在原理实验证明中，我们证明了我们可以制造含有右手配体的铑化合物。然后我们可以获得具有右旋或左旋金属中心的氧化加成产物，并且可以监测这两种异构体的交换。这个交换过程告诉我们具有镜面的中间体（或过渡态）的存在。借助理论和实验，我们可以推断西格玛复合体的存在。其次，该提案通过使用短光脉冲引发反应来测量精心选择的过渡金属化合物与硼化合物的反应速率，解决了硼的特殊性问题。结果将借助与著名理论家爱森斯坦合作进行的理论计算来解释。第三，我们将使用核磁共振波谱来确定不同试剂组合竞争时产物的分布，例如允许硅和硼化合物竞争相同的过渡金属物种。最后，我们将研究据称适合连续进行两个氧化加成反应的过渡金属配合物。这些前体配合物在光照射下发生反应，如果它们可以用可见光而不是紫外光引发，那么它们的应用将特别有趣。总的来说，这项研究将为我们提供不同类型氧化加成反应之间关系的详细描述，这些反应可以用于催化剂设计。