Alkane Oxidation Catalyzed by Mononuclear Non-Heme Iron Complexes

无机化学、生物无机化学和金属有机化学项目的这一奖项支持加州大学圣克鲁斯分校化学系的普拉迪普·K·马斯查拉克博士对烷烃氧化的研究。将合成一系列具有生物相关给体基团的非卟啉配体，并将其用于制备具有C-H键功能化功能的铁配合物。其中一些配体是以博莱霉素为模板的，其铁络合物已被证明具有单加氧酶活性。第二个配体子集包含强场给体基团，以稳定模型络合物中涉及的高价铁中心。第三个配体子集可以容纳基于配体的自由基。所有的配体都是五齿的，它们都会形成扭曲的四方锥形Fe(II)和Fe(III)络合物，当它们与氧气或过氧物反应时，会形成低自旋的过氧铁(III)络合物。正是这种高度氧化的物种有望在温和的条件下促进烷烃和烯烃的快速官能化。系统地改变配体将被用来寻找各种烷烃氧化的最佳条件。将考虑反应速度、产物分布和催化物种的稳定性。反应途径将通过动力学同位素效应研究、自由基捕获和立体化学产物分析来探索。不同的光谱技术(拉曼、X射线、电子顺磁共振、穆斯堡尔谱)将被用来确定中间体的结构和电子特征。本研究的目标是设计新的非血红素单核铁配合物，它可以催化烷烃氧化，也可以用来探索反应途径的细节。烷烃氧化是一个重要的过程，因为甲烷和其他饱和烃含量丰富，有很大潜力作为许多基本化学品的起始原料，但却不易反应。参与该项目的学生将学习合成和仪器分析方面的各种技能，并将在连接生物学和工业催化剂的跨学科努力中获得经验。

This award in the Inorganic, Bioinorganic, and Organometallic Chemistry program supports research on alkane oxidation by Dr. Pradip K. Mascharak of the Chemistry Department, University of California - Santa Cruz. A series of non-porphyrin ligands with biologically relevant donor groups will be synthesized and used to prepare iron complexes that will functionalize C-H bonds. Some of these ligands have been patterned on bleomycin, iron complexes of which have been shown to have monooxygenase activity. A second subset of ligands contains strong field donor groups to stabilize hypervalent iron centers implicated in model complexes. The third subset of ligands can accommodate ligand-based radicals. All the ligands are pentadentate and will afford distorted square pyramidal Fe(II) and Fe(III) complexes that form low spin peroxo Fe(III) complexes when reacted with dioxygen or peroxides. It is this highly oxidizing species that is expected to promote rapid functionalization of alkanes and alkenes under mild conditions. Systematic alteration of ligands will be used to find optimal conditions for oxidation of various alkanes. Reaction rates, product distributions, and stability of the catalytic species will be considered. The reaction pathway will be probed using kinetic isotope effect studies, radical trapping, and stereochemical product analysis. Various spectroscopic techniques (Raman, X-ray, EPR, Mossbauer) will be used to determine the structural and electronic features of the intermediates.The goal of this research is to design new non-heme mononuclear iron complexes that catalyze alkane oxidations and that can also be used to probe the details of the reaction pathways. Alkane oxidation is an important process because methane and other saturated hydrocarbons are abundant and have great potential as starting materials for many essential chemicals, yet are resistant to reaction. Students involved in the project will learn a wide variety of skills in synthesis and instrumental analysis and will gain experience in an interdisciplinary effort that bridges biology and industrial catalyis.