Redox-Active Carborane Clusters for Metal-Free Bond Activation

在化学部化学合成项目的资助下，哥伦比亚南卡罗来纳州大学化学系的Dmitry Peryshkov将研究氧化还原活性碳硼烷簇合物的无金属键活化。许多药物、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。 执行这些键活化具有挑战性，并且已经开发了多种催化剂来执行它们。这些催化剂中的许多需要稀有贵金属如钯、铑、铱和金的化合物。然而，由于对成本、丰度和可持续性的担忧，它们的使用变得越来越成问题。与这一挑战相关，该项目旨在开发不含金属的反应性键断裂和形成系统。该项目的重点是以碳硼烷簇为特征的无金属系统，碳硼烷簇是毒性较低、地球丰富且廉价的元素-硼、碳、磷和氢的化合物。该项目旨在扩大主族元素化学和可持续化学转化中所涉及的反应模式的基础知识。该项目涉及增加大学预科和本科生在研究和化学方面的参与，特别是那些来自科学，技术，工程和数学（STEM）领域的人口统计学通常代表性不足的学生，包括来自历史上的黑人学院和大学，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金属的合成，自由碳硼烷骨架，其具有通过供体位点提供和接受电子以及通过两电子氧化还原态循环的能力。利用这些氧化还原活性碳硼烷基簇的化学性质来实现键活化反应。 将研究双（膦基）-闭合碳硼烷笼接受两个电子并在基底中断裂键的同时成为双阴离子开放巢状簇的能力以及两个膦转化为鳞阳离子的能力。整体反应性可描述为底物氧化加成至整个碳硼烷基二膦分子。本工作将奋进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。为了确定这些簇合物促进的键活化反应的热力学和动力学参数，将进行不饱和羰基化合物的无金属还原中电子和质子转移的研究。该奖项反映了NSF的法定使命，通过使用基金会的知识价值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.