Mechanistic insights into formation and oxidation catalysis of/by FeIV=O and FeV=O: effects of spin state, redox active quinol or oxygen-rich ligands

FeIV=O 和 FeV=O 的形成和氧化催化的机理见解：自旋态、氧化还原活性对苯二酚或富氧配体的影响

• 批准号: 495517454
• 负责人: Professorin Dr. Ivana Ivanovic-Burmazovic
• 金额: --
• 依托单位: Lehrstuhl für Anorganische Chemie
• 依托单位国家: 德国
• 项目类别: Research Units
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/495517454?language=en
• 关键词: Mechanistic; insights; into; formation; oxidation

Nature utilizes extraordinarily reactive high-valent iron oxo species (Fe(IV)=O or Fe(V)=O) in combination with redox-active ligands and second-sphere environment to perform extremely efficient oxygenation reactions. Inspired by this biological approach, in this project we will synthesize a series of mono- or dimeric Fe(II)/Fe(III) complexes containing phenol or quinol redox non-innocent units. Taking advantage of our mechanistic understanding, drawn from our previous research, together with a strong expertise in the application of rather unconventional cryo- and high-pressure-techniques, we will employ the synthesized iron complexes to clarify still-open questions or dichotomies existing in the field. Special attention will be paid to the mechanisms of substrate oxidation by intermediate-spin (IS) and high-spin (HS) Fe(IV)=O species and to the factors affecting the generation and reactivity of Fe(V)=O species in comparison to those of IS and HS Fe(IV)=O intermediates. The iron complexes synthesized for this purpose also represent suitable systems to investigate possible participation of redox non-innocent quinol moieties and/or potential involvement of a (L•)Fe(IV)=O/(L- )Fe(V)=O valence tautomerism in the reactivity of Fe(IV)=O. In addition, they will allow us to explore effects of introducing oxygen donor atoms that provide a weak ligand field around the Fe center, on the spin state and reactivity of the resulting high-valent intermediates. With the aim of mechanistic elucidations and modulation of reaction rates, we will introduce, for the first time in this particular research area, pressure effect studies and combine them with trapping and detecting reaction intermediates by cryo-MS investigations. It should be highlighted that the accomplishment of the objectives intended in this project is only achievable within the collaborative work with other research groups involved in this Research Unit that will share with us their strong expertise in various spectroscopic and/or theoretical methods. Vice versa, our knowledge related to mechanistic investigations and application of rather rare methodologies will be offered to our research collaborators within this Research Unit. A synergic interaction between syntheses and application of a variety of physicochemical methodologies anticipated in the present project will not only advance our understanding of what happens at the active iron center, but can directly provide valuable feedback for the redesign of new generations of functionalized iron complexes displaying more desirable catalytic features.

大自然利用极其活跃的高价铁氧物种（Fe(IV)=O 或 Fe(V)=O）与氧化还原活性配体和第二球体环境相结合来进行极其有效的氧化反应。受这种生物学方法的启发，在这个项目中，我们将合成一系列含有苯酚或对苯二酚氧化还原非无害单元的单聚或二聚 Fe(II)/Fe(III) 配合物。利用我们从之前的研究中得出的机理理解，再加上在非常规低温和高压技术应用方面的强大专业知识，我们将利用合成的铁配合物来澄清该领域中存在的仍然悬而未决的问题或二分法。将特别关注中间自旋（IS）和高自旋（HS）Fe（IV）=O物种的底物氧化机制，以及与IS和HS Fe（IV）=O中间体相比影响Fe（V）=O物种的生成和反应性的因素。为此目的合成的铁配合物也代表了合适的系统，用于研究氧化还原非无辜对苯二酚部分的可能参与和/或 (L•)Fe(IV)=O/(L-)Fe(V)=O 价互变异构在 Fe(IV)=O 反应性中的潜在参与。此外，它们将使我们能够探索引入氧供体原子（在 Fe 中心周围提供弱配体场）对所得高价中间体的自旋态和反应性的影响。为了阐明机理和调节反应速率，我们将在这一特定研究领域首次引入压力效应研究，并将其与通过冷冻质谱研究捕获和检测反应中间体相结合。应该强调的是，该项目预期目标的实现只有在与参与该研究单位的其他研究小组的合作中才能实现，这些研究小组将与我们分享他们在各种光谱和/或理论方法方面的强大专业知识。反之亦然，我们与机械研究和相当罕见的方法学应用相关的知识将提供给该研究单位的研究合作者。本项目中预期的各种物理化学方法的合成和应用之间的协同相互作用不仅将增进我们对活性铁中心发生的情况的理解，而且可以直接为重新设计显示出更理想的催化特性的新一代功能化铁配合物提供有价值的反馈。