Reductive eliminations – trends across the d block

减少消除 â 整个 d 区的趋势

• 批准号: 430582724
• 负责人: Professor Dr. Konrad Koszinowski
• 金额: --
• 依托单位: Institut für Organische und Biomolekulare Chemie
• 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 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/430582724?language=en
• 关键词: Reductive; eliminations; trends; across; block

Reductive eliminations constitute the product-forming step in transition-metal catalyzed C−C, C−CF3, and C−F coupling reactions. The value and potential of these transformations for organic synthesis are truly outstanding. To optimize these reactions in a rational manner, detailed mechanistic insight into the operating catalytic cycles in general and the elementary step of the reductive elimination in particular is needed. Except for the case of palladium- and platinum-mediated reactions, such insight is largely missing. This lack of understanding results from the instability of most of the relevant transition-metal complexes, which has prevented their isolation and in-depth examination. The project aims at circumventing this problem by probing the unimolecular reactivity of ionic complexes isolated in the gas phase. In previous work, the applicant has demonstrated the suitability of electrospray ionization for transferring intact organometallic ions from solution into the gas phase, where mass selection ensures a well-defined population of reactant ions. Collisional activation of these ions and mass-spectrometric detection of the resulting fragment ions afford detailed information on the tendencies of the reactant ions to undergo reductive eliminations or competing processes and the relative barriers of these reactions. The project will include complexes of the medium and late 3d metals as well as selected late 4d and 5d metals and determine the trends that control their unimolecular reactivity. At the same time, it will systematically examine how the overall charge of the complexes, their aggregation state, the oxidation state of the metal center, the coordination of ligands as well as the electronic and steric properties of the metal-bound organyl substituents affect the reductive elimination. The experiments will be moreover complemented by quantum-chemical calculations to obtain additional energetic and structural information. Thus, the studies will greatly advance our fundamental understanding of reductive eliminations and promise to provide guidelines for improving practically important C−C, C−CF3, and C−F coupling reactions.

在过渡金属催化的C-C、C-CF 3和C-F偶联反应中，还原消除构成了产物形成步骤。这些转化对于有机合成的价值和潜力是非常突出的。为了以合理的方式优化这些反应，需要对一般的操作催化循环和特别是还原消除的基本步骤进行详细的机理分析。除了钯和铂介导的反应，这种认识在很大程度上是缺失的。这种缺乏了解的结果，大多数相关的过渡金属配合物的不稳定性，这阻碍了他们的分离和深入研究。该项目旨在通过探测气相中分离的离子络合物的单分子反应性来规避这个问题。在先前的工作中，申请人已经证明了电喷雾电离用于将完整的有机金属离子从溶液转移到气相中的适用性，其中质量选择确保了反应物离子的明确限定的群体。这些离子的碰撞激活和质谱检测所产生的碎片离子提供详细的信息，反应物离子的倾向进行还原消除或竞争过程和这些反应的相对障碍。该项目将包括中期和晚期3d金属以及选定的晚期4d和5d金属的络合物，并确定控制其单分子反应性的趋势。同时，它将系统地研究如何配合物的总电荷，它们的聚集状态，金属中心的氧化态，配体的配位以及金属键合的有机取代基的电子和空间性质影响还原消除。此外，这些实验还将通过量子化学计算得到补充，以获得更多的能量和结构信息。因此，这些研究将大大推进我们对还原消除的基本理解，并有望为改进实际重要的C-C，C-CF 3和C-F偶联反应提供指导。