Heterobimetallic Group 9 Complexes for C-F Bond Activation

通过这个奖项，化学系化学合成项目支持明尼苏达大学双城分校化学系的Connie Lu教授研究有机氟化合物；即以碳氟键（C-F）为特征的化合物。有机氟化合物被用作药剂、杀虫剂、制冷剂、消防泡沫和家具和地毯的防污涂料。C−F键特别牢固，不易断裂。因此，有机氟可以在环境和生理上持续存在和积累。该项目寻求通过破坏相对不活泼的C-F键并用H原子取代所有F原子来化学降解有机氟的方法。方法是利用铑和铱催化剂插入C-F键，以分子氢作为还原剂和氢源。该项目包含强大的教育组成部分，其中本科生和研究生为未来的科学和技术职业进行培训。在推广方面，卢博士将与Antwatin中学的科学教师合作，与大多数代表性不足的学生（50%的非裔美国人，26%的西班牙裔）合作，开发与能源和可持续性相关的动手实验。目前正在研究将过渡金属具有正式零价或亚价氧化态的杂双金属9族（Rh或Ir）配合物作为热或光活化氢除氟反应的试剂和催化剂。这些Rh/Ir配合物中的金属中心由sigma受体金属配体支撑，提供富电子特性，并在这些金属中心上产生增强的亲核性，从而促进C-F键的激活。该项目的具体目标是：(1)合成并表征具有M(0)和M（-1）中心的杂双金属9族配合物；(2)研究了杂双金属配合物对C-F键的热、光化学活化作用；最终，以及(3)开发以C-F键活化为关键步骤的催化反应。如果成功，这项研究的一个重要的、长期的、更广泛的科学影响将在于开发全新的化学物质，以满足社会对降解普遍存在的全氟烷基化合物的需求。该奖项反映了美国国家科学基金会的法定使命，并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 this award, the Chemical Synthesis Program of the Division of Chemistry is supporting Professor Connie Lu of the University of Minnesota–Twin Cities, Department of Chemistry, to study organofluorine compounds; that is, chemical compounds that feature a carbon fluorine (C-F) bond. Organofluorine compounds are used as medicinal agents, insecticides, refrigerants, fire-fighting foam and stain-protective coatings for furniture and carpet. The C−F bond is especially strong and resistant to cleavage. As a consequence, organofluorines can persist and accumulate in the environment and physiologically. This project seeks ways to chemically degrade organofluorines by breaking the relatively unreactive C-F bonds and replacing all the F atoms with H atoms. The methods are to utilize rhodium and iridium catalysts to insert into the C-F bond, with molecular hydrogen serving as the reductant and H source. The project contains a strong educational component in which undergraduate and graduate students are trained for future careers in science and technology. For outreach, Dr. Lu will partner with science teachers at Antwatin Middle School with a majority of underrepresented students (50% African American, 26% Hispanic) to develop hands-on experiments related to energy and sustainability.Heterobimetallic Group 9 (Rh or Ir) complexes where the transition-metal has a formally zero or subvalent oxidation state and is braced are being investigated as reagents and catalysts for heat- or light-activated hydrodefluorination reactions. The metal centers in these Rh/Ir complexes are braced by sigma acceptor metalloligands and provide for electron rich character and engender enhanced nucleophilicity upon these metal centers thereby promoting C-F bond activation. The specific objectives of this project are to: (1) to synthesize and characterize heterobimetallic group 9 complexes bearing formal M(0) and M(-1) centers; (2) to investigate stoichiometric heat- and light-driven C-F bond activation facilitated by the heterobimetallic complexes; and, ultimately, and (3) to develop catalytic reactions that feature C-F bond activation as a key step. If successful, an important long term broader scientific impact of this research will reside in the development of fundamentally new chemistry to address the societal need to degrade pervasive perfluoroalkyl compounds.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.