Bond activation reactions by means of metal ligand cooperation in carbene complexes

卡宾配合物中金属配体合作的键活化反应

• 批准号: 428484823
• 负责人: Professorin Dr. Viktoria H. Däschlein-Geßner
• 金额: --
• 依托单位: Lehrstuhl für Anorganische Chemie II: Metallorganische Chemie und Katalyse (AG Gessner)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/428484823?language=en
• 关键词: Bond; activation; reactions; means; metal

The activation of element element and element hydrogen bonds is a fundamental process in many transition metal catalyzed transformations. Typically, these processes directly occur at the metal center via an oxidative addition step. In the last years however, mechanisms involving both the metal as well as the ligand as active sites in the bond breaking and making steps have become an alternative tool in bond activation chemistry. The development of novel ligand systems has led to the incorporation of this metal ligand cooperativity into stoichiometric as well as catalytic transformations, thus opening new possibilities for future processes in homogenous catalysis. Well-established examples for such cooperating ligands are imido, amido or carbonyl-functionalized ligands. In contrast, carbene ligands are by far less explored in this chemistry and their application limited to only few examples. Goal of the present research proposal is to overcome this lack in carbene chemistry and to establish carbene complexes in cooperative bond activation reactions and catalysis. To this end, the systematic design of complexes with cooperating carbene ligands, their application in bond activation reactions as well as an understanding of the electronic demands on the M=C interaction will be addressed. Thereby two different types of carbene systems will be targeted: i) methandiide-derived carbene complexes as well as ii) complexes based on PCD pincer ligands. Variation of the substituents in the ligands will influence the electronics of the metal carbon interaction and thus allow for controlled E–E- and E–H bond activation reactions via addition across the M=C bond. Systematic experimental as well as computational studies will provide a profound understanding of the relations between the molecular and electronic structures of the designed systems and their applicability as cooperating ligands. Thus, reversible activation processes of different E–E- und E–H bonds as well as their transfer to organic substrates will be realized. This will be basis for the final development of catalytic transformations. Here, we will also focus on acceptor-less dehydrogenation reactions for the production and storage of dihydrogen.

元素、元素氢键的活化是许多过渡金属催化转化的基本过程。通常，这些过程通过氧化加成步骤直接发生在金属中心。然而，在过去的几年中，涉及金属以及配体作为键断裂和键形成步骤中的活性位点的机制已经成为键活化化学中的替代工具。新型配体系统的发展导致将这种金属配体协同性纳入化学计量以及催化转化，从而为未来均相催化过程开辟了新的可能性。此类配合配体的公认实例是亚氨基、酰胺基或羰基官能化配体。相比之下，碳烯配体在该化学中的探索要少得多，并且它们的应用仅限于少数实例。本研究的目标是克服卡宾化学中的这一缺陷，并在协同键活化反应和催化中建立卡宾络合物。为此，配合物的系统设计与合作的卡宾配体，它们在键活化反应中的应用，以及对M=C相互作用的电子需求的理解将得到解决。因此，将靶向两种不同类型的卡宾体系：i）甲烷二亚胺衍生的卡宾络合物以及ii）基于PCD钳形配体的络合物。配体中取代基的变化将影响金属碳相互作用的电子学，从而允许通过跨M=C键的加成进行受控的E-E-和E-H键活化反应。系统的实验以及计算研究将提供一个深刻的理解之间的关系的分子和电子结构的设计系统和它们的适用性作为合作配体。因此，将实现不同的E-E-和E-H键的可逆活化过程以及它们向有机基底的转移。这将是催化转化最终发展的基础。在这里，我们还将关注用于生产和储存氢的无受体脱氢反应。