Redox-Active Carborane Clusters for Metal-Free Bond Activation

在化学部化学合成项目的资助下，南卡罗来纳大学哥伦比亚分校化学系的德米特里·佩里什科夫将研究氧化还原活性碳硼烷簇合物的无金属键激活。许多药品、塑料、染料和电子材料的工业制备涉及化学键的精确断裂和形成。执行这些键活化是具有挑战性的，已经开发了各种催化剂来执行它们。其中许多催化剂需要稀有的贵金属化合物，如钯、铑、铱和金。然而，由于对成本、丰度和可持续性的担忧，它们的使用正变得越来越成问题。与这一挑战相关的是，该项目旨在开发不含金属的反应性断键和形成系统。该项目专注于以碳硼烷簇合物为特征的无金属系统，这是一种毒性较低、富含地球资源且价格低廉的元素--硼、碳、磷和氢的化合物。该项目旨在扩大可持续化学转化所涉及的主要族元素化学和反应模式的基础知识。该项目涉及增加大学预科和本科生对研究和化学的参与，特别是那些来自人口统计学领域通常在科学、技术、工程和数学(STEM)领域代表性较低的学生，包括来自历史上一直是黑人的学院和大学，如克拉夫林大学，南卡罗来纳州最古老的HBCU。该项目的主要重点是合成无金属碳硼烷框架，这些框架能够通过供体位置捐赠和接受电子，并在两电子氧化还原状态之间循环。这些具有氧化还原活性的碳硼基簇合物的化学性质被用来实现键活化反应。将研究双(膦)-闭合碳硼烷笼子在断裂底物上的键时接受两个电子并成为一个双阴离子开放的NIDO-簇的能力，以及两个膦转化为膦离子的能力。总的反应性可以描述为底物氧化加成到整个Carboranyl双膦分子上。这项工作将努力建立基于电化学数据、结构和光谱参数以及计算的增强反应性的设计原则。为了建立由这些簇合物促进的键活化反应的热力学和动力学参数，将对不饱和羰基化合物无金属还原过程中的电子和质子转移进行研究。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

With funding from the Chemical Synthesis program in the Chemistry Division, Dmitry Peryshkov from the Department of Chemistry at the University of South Carolina at Columbia, will investigate redox-active carborane clusters for metal-free bond activation. The industrial preparation of many pharmaceuticals, plastics, dyes and electronic materials involves the precise breaking and forming of chemical bonds. Performing these bond activations is challenging and a diverse range of catalysts have been developed to perform them. Many of these catalysts require compounds of scarce, precious metals such as palladium, rhodium, iridium, and gold. However, their use is becoming increasingly problematic due to concerns around cost, abundance, and sustainability. Relevant to this challenge, this project is directed toward developing reactive bond-breaking and forming systems that do not contain metals. The project is focused on metal-free systems featuring carborane clusters, which are compounds of less toxic, earth-abundant, and inexpensive elements – boron, carbon, phosphorus, and hydrogen. The project is directed toward expanding fundamental knowledge of main group element chemistry and reactivity patterns involved in sustainable chemical transformations. The project involves increased participation of pre-college and undergraduate students in research and chemistry, especially those from demographics typically underrepresented in science, technology, engineering, and mathematics (STEM) fields, including from Historically Black Colleges and Universities, such as Claflin University, the oldest HBCU in South Carolina.The main focus of this project is the synthesis of metal-free carborane frameworks that have the ability to donate and accept electrons through donor sites and to cycle through two-electron redox states. The chemical properties of these redox-active carboranyl clusters are utilized to enable bond activation reactions. The ability of the bis(phosphino)-closo-carborane cage to accept two electrons and become a dianionic open nido-cluster while breaking a bond in a substrate and the two phosphines converting to phosphonium cations will be studied. The overall reactivity may be described as the oxidative addition of a substrate to the whole carboranyl diphosphine molecule. This work will endeavor to establish the design principles for enhancing reactivity based on electrochemical data, structural and spectroscopical parameters, and computation. In order to establish the thermodynamic and kinetic parameters for bond activation reactions promoted by these cluster compounds, studies of the transfer of electrons and protons in the metal-free reduction of unsaturated carbonyl compounds will be conducted.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.