High-Valent Metal-Oxo Species: Beyond the Oxo Wall

高价金属氧化物种：超越氧化墙

• 批准号: 1900380
• 负责人: Nicolai Lehnert
• 金额: $ 45万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-01 至 2023-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1900380&HistoricalAwards=false
• 关键词: Valent; Metal; Oxo; Species; Beyond

With funding from the Chemical Structure, Dynamics and Mechanisms B Program of the NSF Chemistry Division, the collaborative research team of Professor Lehnert of University of Michigan and Professor Shearer of Trinity University investigates different Cobalt- and Nickel-based oxo complexes to improve the understanding of the structural and electronic properties of these unstable species. Metal-oxo species are often implicated in enzymatic and synthetic catalysis and play key roles in hormone biosynthesis, drug metabolism, and in photosynthesis. In the chemical and pharmaceutical industry, reactive metal-oxo complexes are used as catalysts for the production of chemical feedstocks and in the synthesis of fine chemicals and pharmaceuticals. Currently, scientists are lacking a detailed understanding of the properties of late-transition metal oxo species, which show great potential for applications in chemical catalysis, but which are underutilized as scientists cannot control their reactivity well. Professor Lehnert is the director of the D-RISE program, which provides 7-weeks, full-time summer research opportunities to high school students from Detroit that belong to underrepresented minority (URM) groups in science, technology, engineering and math (STEM) disciplines. The activities include funding for one high school student to participate in D-RISE. Professor Shearer conducts research exclusively with undergraduate students recruited through mechanisms that aim at increasing the participation of URM students in the sciences (in particular, Trinity University's McNair Scholar's program). Professor Lehnert and Professor Shearer are developing an understanding of the structural and electronic properties of a number of high-valent Co- and Nickel-oxo complexes. Especially the effect of the spin state on the electronic properties of these complexes is underappreciated; yet, as demonstrated for iron-oxo complexes, the spin state has a pivotal influence on the reactivity of these species. In the case of Co-oxo complexes, spin state also provides a potential pathway for a true violation of the "oxo wall", a concept that is considered a holy grail in high-valent metal-oxo chemistry. Another important dichotomy of metal-oxo complexes is the question of whether they are best represented as metal-oxo or metal-oxyl species, and how this influences their reactivity. Therefore, the research on the fundamental properties of high-valent Co- and Nickel-oxo complexes addresses many important fundamental questions about high-valent metal-oxo complexes with general (conceptual) implications for this area of research. The proposed research has broad implications with respect to further developing late first-row transition metal catalysts for water oxidation and the functionalization of organic molecules. In particular, bioinspired catalysts for the functionalization of organic molecules are highly sought after as industrial catalysts for the production of chemical feedstocks and pharmaceuticals. This project employs a large array of spectroscopic and theoretical methods, including electron paramagnetic resonance, magnetic circular dichroism, resonance Raman, and X-ray absorption spectroscopy. Theoretical methods (density functional theory and multi-reference quantum-chemical calculations) are used to interrogate the spectroscopic results, and connect them to electronic structure and reactivity. Professor Lehnert is actively engaged in STEM outreach programs focused on recruiting underrepresented minority (URM) high school students from Detroit to STEM fields. Professor Shearer's laboratory works exclusively with undergraduate (UG) students, which are recruited through mechanisms that aim at increasing the participation of URM UG students in the sciences (in particular, Trinity University's McNair Scholar's program). Both of these activities support the broader impacts of the 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.

在美国国家科学基金会化学部化学结构、动力学和机理B计划的资助下，密歇根大学的Lehnert教授和三一大学的Sheeller教授组成的合作研究小组研究了不同的钴和镍基氧化合物，以提高对这些不稳定物种的结构和电子性质的了解。金属氧物种通常涉及酶催化和合成催化，并在激素生物合成、药物代谢和光合作用中发挥关键作用。在化工和制药工业中，活性金属氧络合物被用作生产化学原料以及合成精细化学品和药物的催化剂。目前，科学家们对后过渡金属氧物种的性质缺乏详细的了解，这些物种在化学催化中显示出巨大的应用潜力，但由于科学家无法很好地控制其反应活性，因此没有得到充分的利用。Lehnert教授是D-Rise项目的负责人，该项目为底特律的高中生提供为期7周的全日制暑期研究机会，这些学生属于科学、技术、工程和数学(STEM)学科中代表不足的少数群体(URM)。这些活动包括资助一名高中生参加D-RISE。希勒教授专门针对通过机制招募的本科生进行研究，这些机制旨在增加URM学生对科学的参与(特别是三一大学的麦克奈尔学者计划)。Lehnert教授和Sheeller教授正在发展对一些高价钴和镍氧化合物的结构和电子性质的理解。特别是自旋态对这些化合物的电子性质的影响被低估；然而，正如铁-氧化合物所证明的那样，自旋态对这些物种的反应活性有关键的影响。在Co-oxo络合物的情况下，自旋态也为真正破坏“氧代壁”提供了一条潜在的途径，这一概念被认为是高价金属-氧代化学中的圣杯。金属氧络合物的另一个重要的二分法是，它们是金属氧基还是金属氧基物种，以及这如何影响它们的反应活性的问题。因此，高价钴镍氧络合物基本性质的研究解决了高价金属氧络合物的许多重要的基本问题，对这一领域的研究具有普遍的(概念)意义。该研究对进一步开发晚期第一排过渡金属水氧化催化剂和有机分子功能化具有广泛的指导意义。特别是，用于有机分子功能化的仿生催化剂作为生产化学原料和药品的工业催化剂而备受追捧。该项目使用了大量的光谱和理论方法，包括电子顺磁共振、磁圆二色谱、共振拉曼光谱和X射线吸收光谱。理论方法(密度泛函理论和多参考量子化学计算)被用来询问光谱结果，并将它们与电子结构和反应性联系起来。Lehnert教授积极参与STEM推广计划，重点是从底特律招募代表不足的少数族裔(URM)高中生到STEM领域。希勒教授的实验室专门面向本科生(UG)，这些学生是通过旨在增加UG学生对科学的参与度的机制招募的(特别是三一大学的麦克奈尔学者计划)。这两项活动都支持该项目更广泛的影响。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。

项目成果

Preparation and Characterization of a Formally Ni IV –Oxo Complex with a Triplet Ground State and Application in Oxidation Reactions

具有三重基态的形式 Ni IV -Oxo 配合物的制备和表征及其在氧化反应中的应用

• DOI: 10.1021/jacs.2c10196
• 发表时间: 2022
• 期刊: Journal of the American Chemical Society
• 影响因子: 15
• 作者: Karmalkar, Deepika G.;Larson, Virginia A.;Malik, Deesha D.;Lee, Yong-Min;Seo, Mi Sook;Kim, Jin;Vasiliauskas, Dovydas;Shearer, Jason;Lehnert, Nicolai;Nam, Wonwoo
• 通讯作者: Nam, Wonwoo