Synthesis of Diiron(IV)-Oxo Complexes of Relevance to Methane Monoyxgenase

项目概述：几乎在所有的好氧生物中发现，具有非血红素铁的氧活化酶 中心经常被用来执行要求高的转换。本研究项目的主要目的是 是通过合成铁酶来深入了解氧活化的性质， 模拟关键催化剂的结构和反应性的高价铁-氧代络合物的表征 中间体的特别是，将采用新的策略来产生模拟反应性的复合物。 可溶性甲烷单加氧酶（MMO）是一种利用氧气将甲烷转化为 甲醇。通过允许某些细菌利用甲烷作为其唯一的碳和能量来源， 每年从大气中消除近10亿吨这种强效温室气体。此外，委员会认为， 在工业上复制MMO反应以提供一种 甲醇是一种化学原料和潜在能源，是一种环境清洁的生产方法。 因此，高价二铁物种的研究具有巨大的生物学、环境和技术意义。 影响 sMMO催化循环中的关键步骤涉及甲烷的氧化， 特征在于已知为中间体Q的二铁（IV）-氧代物质。在最近成功地 产生单核铁（IV）-氧代配合物，该提案描述了两种原始路线， 合成中间体Q的小分子模型，其再现其双-氧代-二铁（IV）“金刚石核”。 所得复合物将用各种光谱和结构方法表征，例如 如电子吸收、共振拉曼、穆斯堡尔和X射线吸收光谱，及其 将检查对有机底物的反应性。这些结果有望推动我们目前的 了解中间体Q的几何和电子结构，并提供新的见解， 生物系统中的氧活化机制。此外，该项目可能会导致发展 甲烷氧化的仿生催化剂。 相关性：通过合成小分子铁复合物，复制铁的结构和反应性， 重要的生物物种，这项研究提案旨在更好地了解人类的这些过程 以及其他需要在酶中的铁中心处进行氧活化的生物。此外，该项目可能 导致新的催化剂的发展，这将使化学家使用氧气进行环境- 碳氢化合物的友好转化，从而减少污染和温室气体的水平 气氛

Project Summary: Found in nearly all aerobic organisms, oxygen-activating enzymes with non-heme iron centers are often employed to perform demanding transformations. The major aim of this research project is to gain insights into the nature of oxygen activation at iron enzymes through the synthesis and characterization of high-valent iron-oxo complexes that mimic the structure and reactivity of key catalytic intermediates. In particular, novel strategies will be employed to generate complexes that model the reactive species of soluble methane monooxygenase (MMO), an enzyme that uses oxygen to convert methane to methanol. By allowing certain bacteria to utilize methane as their sole source of carbon and energy, MMOs eliminate nearly a billion tons of this potent greenhouse gas from the atmosphere each year. Moreover, there is considerable interest in replicating the MMO reaction industrially in order to provide an environmentally-clean means of generating methanol, a chemical feedstock and potential energy source. Thus, the study of high-valent diiron species carries enormous biological, environmental, and technological implications. The crucial step in the sMMO catalytic cycle involves the oxidation of methane by a poorly- characterized diiron(IV)-oxo species known as intermediate Q. Building upon the recent success in generating mononuclear iron(IV)-oxo complexes, this proposal describes two original routes for the synthesis of small-molecule models of intermediate Q that reproduce its bis-oxo-diiron(IV) "diamond core". The resulting complexes will be characterized with a variety of spectroscopic and structural methods, such as electronic absorption, resonance Raman, Mossbauer and X-ray absorption spectroscopies, and their reactivites towards organic substrates will be examined. The results are expected to advance our current understanding of the geometric and electronic structures of intermediate Q, and provide new insights into mechanism of oxygen activation in biological systems. Additionally, this project may lead to the development of biomimetic catalysts for methane oxidation. Relevance: By synthesizing small-molecule iron complexes that replicate the structures and reactivities of important biological species, this research proposal aims to better understand those processes in humans and other organisms that require oxygen activation at iron centers in enzymes. Additionally, this project may lead to the development of new catalysts that will allow chemists to use oxygen to carry out environmentally- friendly transformations of hydrocarbons, thereby reducing pollution and levels of greenhouse gases in the atmosphere.