XAS STUDIES OF HIGH-VALENT FE MODEL COMPLEXES RELEVANT TO METHANE MONOOXYGENASE

甲烷单加氧酶相关高价FE模型复合物的XAS研究

• 批准号: 7954370
• 负责人: SERENA D DE BEER GEORGE
• 金额: $ 0.56万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-03-01 至 2010-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7954370
• 关键词: Amines; Biomimetics; Catalysis; Complex; Computer Retrieval of Information on Scientific Projects Database; Data; Drug Formulations; Funding; Grant; Institution; Iron; Laboratories; Ligands; Methane; Methane hydroxylase; Methanol; Modeling; Mononuclear; Reaction; Relative (related person); Research; Research Personnel; Resources; Ribonucleotide Reductase; Ribonucleotides; Solutions; Source; Structure; United States National Institutes of Health; Work; analog; cold temperature; electronic structure; oxidation; phenolate; phenoxy radical; structural biology; synchrotron radiation

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. High-valent iron intermediates are invoked as the active oxidizing species in both methane monooxygenase (MMO) and ribonucleotide reductase (RNR). In MMO, intermediate Q is thought to consist of an FeIV(mu-O)2FeIV core which converts methane to methanol. Whereas in RNR, an oxo-bridged FeIIIFeIV species, intermediate X is the active species in ribonucleotide reduction. The importance of these reactions and the potential utility of synthetic analogues in biomimetic homogeneous catalysis have driven efforts to synthesize analogues. Recent work in our laboratory has focused on the synthesis and characterization of dinuclear Fe-oxo complexes utilizing strongly pi- and sigma- donating phenolates and t-amines as donors. The resultant [LFe(mu2-O)FeL] complex (1) can be oxidized to the monocation [LFe(mu2-O)FeL]+ (1+) and to the dication [LFe(mu2-O)FeL]2+ (12+). EPR data of 1+ suggests an oxo-bridged-FeIIIFeIV formulation. However comparison of UV-vis data for 1+ and 2+ to mononuclear analogues suggests a ligand-centered oxidation occurs in both complexes, forming a diferric phenoxyl radical in 1+ and a diferric diphenoxyl radical in 12+. The greater stability of the dication relative to the monoanionic species is thought to result from a symmetric strengthening of the Fe-oxo bonds in the former (12+), as opposed to the asymmetric situation which is generated in the later (1+). As these species can only be generated at low temperature in solution, XAS provides an ideal means for characterizing the electronic structure and local geometric structure of these complexes.

该副本是利用众多研究子项目之一 由NIH/NCRR资助的中心赠款提供的资源。子弹和 调查员（PI）可能已经从其他NIH来源获得了主要资金， 因此可以在其他清晰的条目中代表。列出的机构是 对于中心，这不一定是调查员的机构。 高价值铁中间体被称为甲烷单加氧酶（MMO）和核糖核苷酸还原酶（RNR）中的活性氧化物种。在MMO中​​，中间Q被认为由FEIV（MU-O）2FEIV核心组成，该核心将甲烷转化为甲醇。 而在RNR中，含氧桥的Feiiiiviv物种，中间X是核糖核苷酸还原的活性物种。这些反应的重要性以及合成类似物在仿生均匀催化中的潜在实用性促进了综合类似物的努力。我们实验室的最新工作集中在利用强烈的pi-oxo oxo络合物的合成和表征上，利用强烈的pi-pi-oxo氧化酚和sigma捐赠酚酸酯和T-胺作为捐助者。所得[LFE（MU2-O）FEL]复合物（1）可以氧化为单位[LFE（MU2-O）FEL]+（1+），并氧化为[LFE（MU2-O）FEL] 2+（12+）。 1+的EPR数据表明含氧桥的含量。然而，将1+和2+的UV-VIS数据与单核类似物进行比较表明，在两个复合物中都会发生以配体为中心的氧化，从而形成1+中的差异苯氧基自由基，而在12+中形成了差异的二脑氧基自由基。人们认为，与单​​氨基离子物种相对的稳定性较高，这是由于前者（12+）中的Fe-oxo键的对称增强而导致的，而不是后来（1+）产生的不对称情况。由于这些物种只能在溶液中的低温下生成，因此XAS提供了表征这些复合物的电子结构和局部几何结构的理想手段。