CAREER: Cavity-Enforced Structure and Reactivity of High-Valent Iron Oxo, Nitrosyl, and Superoxo Complexes

在化学系化学合成项目的支持下，罗切斯特大学的布兰登·r·巴内特正在研究生物启发的铁配合物的合成，这种配合物可以在化学反应中促进强碳氢键的断裂。这一过程对于化学工业是必不可少的，因为许多重要的过程需要在通常的化学原料中打破这种键。提出的工作旨在开发方法来执行这样的反应，并施加精细控制的碳-氢裂解过程。这些研究将进一步制定战略，使新的铁化合物能够用作催化剂，并使原料能够有效地转化为增值产品。协同作用是，拟议的工作将培养早期职业受训者的基本技术和非技术技能，并促进来自代表性不足背景的学生参与现代化学研究。此外，该项目非常适合不同教育水平和社区的学生进行外展和培训。除了将本科生的研究纳入该项目之外，PI还将启动一个夏季系列研讨会，旨在培养本科生化学研究人员的“软技能”。与此相辅相成的是一项计划，旨在将市中心的高中生与拟议的研究联系起来，并将虚拟现实技术纳入研究生课程。拟议的研究将进行C-H活化的腔封闭铁(IV)-氧的机制调查，这将大大有助于处理这些配合物在环境和适度升高的温度的能力。重要的是，预计空腔的刚性性质允许C-H活化的空间选择性，因此区域选择性是由键的空间可及性而不是其强度决定的。将启动对净碳氢功能化的调查，以及能够实现催化周转的有针对性的方法。作为范围的延伸，拟议的工作还将阐明空间限制对铁超氧和亚硝基配合物的电子和几何结构的影响。目标高价铁配合物将使用一个配体系统，该配体系统包含一个有机大环，顶部是一个三角形金属螯合平台。这些被设计用来包围并在动力学上稳定活性金属结合碎片。提出的工作旨在利用空腔强制低热力学稳定性构象、抑制常见降解途径和控制底物途径之间的相互作用，从而实现区域选择性碳氢化合物功能化，如果成功，可能具有广泛的科学影响和应用。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 support from the Chemical Synthesis program of the Division of Chemistry, Brandon R. Barnett of the University of Rochester is investigating the synthesis of biologically-inspired iron complexes that can facilitate the breaking of strong carbon-hydrogen bonds during chemical reactions. This process is essential for the chemical industry where many important processes require the breaking of such bonds in the usual chemical feedstocks. The proposed work aims to develop ways to perform such reactions and exert fine control over the carbon-hydrogen cleavage process. These studies will further develop strategies that enable the new iron compounds to be employed as catalysts and enable the efficient conversion of feedstocks to value-added products. Synergistically, the proposed work will develop essential technical and non-technical skill sets of early career trainees and facilitate the engagement of students from underrepresented backgrounds in modern chemistry research. Additionally, this project is well suited for outreach and training of students from across multiple educational levels and communities. Beyond the incorporation of undergraduate research into this project, the PI will initiate a summer workshop series, with the aim of developing the “soft skills” of undergraduate chemistry researchers. Complementing this effort is a plan to interface inner-city high school students with the proposed research, and to incorporate virtual reality technology into the graduate level curriculum.The proposed research will undertake mechanistic investigations of C-H activation by cavity-enclosed iron(IV)-oxos, which will be greatly aided by the ability to handle these complexes at ambient and moderately elevated temperatures. Importantly, the rigid nature of the cavity is anticipated to allow for steric selectivity in C-H activation, whereby regioselectivity is determined by the steric accessibility of the bond rather than its strength. Investigations into net C-H functionalization will be initiated, as will targeted approaches that can enable catalytic turnover. As an extension of scope, the proposed work will also elucidate the effects of spatial confinement on the electronic and geometric structures of iron superoxo and nitrosyl complexes. The targeted high-valent iron complexe will be built using a ligand system that contains an organic macrocycle atop a trigonal metal-chelating platform. These are designed to surround and kinetically stabilize the reactive metal-bound fragments. The proposed work aims to exploit an interplay between the ability of the cavity to enforce conformations of low thermodynamic stability, to suppress common degradation pathways, and to control substrate approach so as to achieve regioselective C-H functionalization, with potentially broad scientific impact and application, if successful.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.