CAREER: SusChEM: Metal-Metal Bonds as Active Sites in Catalysis

在这项由化学系化学催化计划资助的项目中，普渡大学化学系教授克里斯托弗·乌耶达研究了含有双核活性中心的分子过渡金属催化剂。在自然界中，包含两种或两种以上金属的高度复杂的系统进行电子转移转换，这是生物合成和能量管理的核心。相比之下，目前用于促进相关反应的分子催化剂结构相对简单，最常见的是只含有一个金属中心。这种单一的金属必须调解所有的键断裂和形成事件。原则上，含有多种金属的新型催化剂可以像自然生成的体系中看到的那样显示出金属协同性。与更成熟的单核化合物相比，这些化合物可能会显示出独特的性质。这项研究旨在发展设计坚固高效的合成多核催化剂的基本原理。该项目还包含一个教育部分，将向高中生和本科生介绍催化研究。在普渡大学提供这样的研究机会对高中生参与尖端研究有积极的影响。这项研究的重点是开发新的氧化还原活性配体结构，以支持特定组成的金属-金属键。通过利用以配体为中心的氧化还原对，所得到的双核配合物能够在许多基本的双电子过程中与有机底物接触(例如，氧化加成和还原消除)，这些过程构成了催化转化的基础。这个项目的主要目标是将金属-金属键的电子特征与它们在催化中的活性和选择性联系起来。因此，通过(1)通过实验和理论相结合的方法建立电子结构模型，(2)表征看似合理的催化中间体，(3)利用反应动力学和其他物理有机技术研究催化过程，以及(4)对单核和双核催化剂进行良好控制的比较研究，寻求对这些体系的详细的机理见解。这些活动与教育部分相结合，重点是为包括当地高中生在内的年轻学生提供参与大学实验室正在进行的催化研究的机会。

In this project supported by the Chemical Catalysis Program of the Chemistry Division, Professor Christopher Uyeda of the Department of Chemistry at Purdue University studies molecular transition metal catalysts containing dinuclear active sites. In nature highly complex systems that contain two or more metals carry out electron transfer transformations that are central to biosynthesis and energy management. In contrast, molecular catalysts that are currently used to promote related reactions have comparatively simple structures, most commonly containing just a single metal center. This single metal must mediate all of the bond-breaking and forming events. In principle, new classes of catalysts that contain multiple metals could exhibit metal cooperativity as seen in the naturally occurring systems. These could exhibit unique properties as compared to their more well-established mononuclear counterparts. This research aims to develop the fundamental principles underlying the design of robust and efficient synthetic multinuclear catalysts. The project also contains an educational component that will introduce high school and beginning undergraduate students to catalysis research. Providing such research opportunities at Purdue positively impacts the engagement of high school students in cutting-edge research. This research focuses on the development of new redox-active ligand architectures that support metal-metal bonds of defined composition. By capitalizing on ligand-centered redox couples, the resulting dinuclear complexes are capable of engaging organic substrates in many of the elementary two-electron processes (e.g. oxidative additions and reductive eliminations) that form the basis for catalytic transformations. An overarching goal of this project is to connect the electronic features of metal-metal bonds to their activity and selectivity in catalysis. As such, detailed mechanistic insights into these systems are sought by (1) developing electronic structure models through a combination of experiment and theory, (2) characterizing plausible catalytic intermediates, (3) studying catalytic processes using reaction kinetics and other physical organic techniques, and (4) conducting well-controlled comparative studies between mononuclear and dinuclear catalysts. These activities are integrated with an educational component that focuses on providing opportunities for young students, including local high school students, to engage in the catalysis research being carried out in university labs.