CAS: Structure, Bonding and Mechanism in Iron-Catalyzed C-H Functionalization

发展可持续、更高效、更有选择性的催化仍然是化学基础研究的关键目标之一。为了实现这一目标，能够直接将碳-氢(C-H)键转化为新的感兴趣的化学键的铁催化剂是一种特别有吸引力的方法，无论是在反应效率方面，还是铁的广泛可获得性、低成本和最小毒性方面都是特别有吸引力的方法。不幸的是，由于缺乏对催化物种和反应步骤的基本了解，这类反应的发展目前受到阻碍。在这个项目中，罗切斯特大学的内迪格博士正在确定哪些铁物种负责有效的催化，这些铁物种如何反应形成所需的反应产物，以及催化剂结构和成键与反应活性的关系。这些研究的基本结论将有助于合理设计和开发在先进化工制造中提高C-H官能化性能的铁催化剂。内迪格博士积极参与多项外展活动，以促进学生对科学、技术和数学学科的培训和参与。这些活动包括为当地社区大学和代表性不足的高中生提供研究机会，旨在鼓励下一代学生追求科学事业。罗切斯特大学的内迪格在化学系化学结构、动力学和机理B项目的资助下，正在对铁催化的C-H官能化中的活性催化剂种类和潜在的催化分子机理进行详细的基础了解。这一认识是通过多种无机光谱(磁圆二色谱、穆斯堡尔谱、电子顺磁共振和共振拉曼光谱)、密度泛函理论、合成以及动力学和反应研究相结合的方法实现的。具体研究包括确定铁(II)/铁(III)/铁(I)机制循环的细节及其在其他C-H官能化反应中的更广泛作用，以及评估拟议的铁(III)/铁(I)和低价铁反应歧管用于C-H官能化，以确定和定义有针对性的合理方法开发的替代机制框架。进一步的研究正在研究还原的铁-膦络合物、反应中间体和在没有导向基团的情况下实现有效的C-H官能化催化的机理，包括使有效的C-H官能化的关键配体性质。内迪格博士在罗切斯特市学区与当地社区大学生和教师以及代表不足的高中生积极参与STEM外展研究项目，以支持该项目的更广泛影响。该奖项反映了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。

The development of sustainable, more efficient and selective catalysis remains one of the key fundamental research goals in chemistry. Towards this goal, iron catalysts that can directly transform carbon-hydrogen (C-H) bonds into new chemical bonds of interest is a particularly attractive method, both in terms of reaction efficiency as well as the wide availability, low cost and minimal toxicity of iron. Unfortunately, the development of such reactions is currently hindered by the lack of fundamental understanding of the catalytic species and reaction steps involved. In this project, Dr. Neidig from the University of Rochester is identifying which iron species are responsible for effective catalysis, how these species react to form the desired reaction products, and how catalyst structure and bonding relates to reactivity. The fundamental insight obtained in these studies will serve to facilitate and inspire the rational design and development of iron catalysts with improved performance in C-H functionalization in advanced chemical manufacturing. Dr. Neidig is actively engaged in several outreach activities that promote student training and engagement in science, technology and mathematics disciplines. These activities, which include research opportunities for both local community college and underrepresented high school students as well, are aimed at encouraging the next generation of students to pursue careers in science.Dr. Neidig of the University of Rochester, with funding from the Chemical Structure, Dynamics and Mechanisms-B Program of the Chemistry Division, is developing a detailed fundamental understanding into the active catalyst species and underlying molecular mechanisms of catalysis in iron-catalyzed C-H functionalization. This insight is achieved through an approach combining multiple inorganic spectroscopies (magnetic circular dichroism, Mössbauer, electron paramagnetic resonance, and resonance Raman), density functional theory, synthesis and kinetic and reaction studies. Specific studies include defining the details of the iron(II)/iron(III)/iron(I) mechanistic cycle and its broader role across additional C-H functionalization reactions, as well as evaluating proposed iron(III)/iron(I) and low-valent iron reaction manifolds for C-H functionalization in order to identify and define alternative mechanistic frameworks for targeted, rational methods development. Further studies are investigating the reduced iron-phosphine complexes, reaction intermediates and mechanism enabling effective C-H functionalization catalysis in the absence of directing groups, including key ligand properties that enable effective C-H functionalization. Dr. Neidig is actively engaged in STEM outreach research programs with local community college students and faculty as well as underrepresented high school students in the Rochester City School District, in support of the broader impacts of this project.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.