High-valent metal oxo species stabilized by polyoxovanadates: synthesis, properties and catalytic activity

多钒酸盐稳定的高价金属氧物种：合成、性能和催化活性

• 批准号: 389183496
• 负责人: Professor Dr. Carsten Streb
• 金额: --
• 依托单位: Lehrstuhl für Anorganische und Allgemeine Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/389183496?language=en
• 关键词: valent; metal; oxo; species; stabilized

High-valent metal oxo species are considered key intermediates in various industrial and biological catalytic processes. This project investigates the formation, reactivity and possible stabilization of high-valent metal oxo and metal-hydroxo species in novel molecular vanadium oxide clusters. Metal-functionalized vanadium oxides [M(L)V12O32X]n- (= {MV12}, M = transition metal, L = terminal ligand, X = halide-template) with a pre-formed metal binding site are used as suitable models for the generation and possible stabilization of high-valent metal species as their oxidative-catalytic activity has been shown previously. In particular, this project is focused on redox-active 3d-transition metals with multiple accessible redox-transitions (FeII, MnII, CoII) as potentially relevant models for industrial catalysts (e.g. Haber-Bosch process) as well as enzymes (e.g. cytochrome P450). In addition, selected 4d/5d metals (RuII, IrII) are employed as they can facilitate the isolation and structural characterization of high-valent oxo complexes. The binding mode of metal centres in {MV12} is fundamentally different to typical metal oxo ligands (often: nitrogen donors with trigonal coordination geometry), therefore new intermediates with a previously un-explored coordination behaviour and new reactivity can be expected. In the first step, the formation of high-valent species by reaction of existing {MV12} complexes with reactive ligands such as peroxides and azides as well as the activation of molecular oxygen by reduced {MV12} species is investigated. High-valent intermediates are characterized using experimental and theoretical methods to understand their electronic structure, binding modes and reactivity. Whenever possible, structural characterization using single-crystal X-ray diffraction will provide detailed insight into the binding situation. The reactivity of the high-valent species as well as their possible use as catalysts will be explored using synthetically important substrate oxidations, e.g. epoxidations, C-H-activations and hydroxylations. In situ stability studies will provide insight into possible cluster rearrangement or colloid formation. The project therefore provides access to a completely new compound class whose reactivity can be rationalized based on the intermediates formed and where reactivity can be tuned by chemical modification of the metal centres present.

高价金属含氧物种被认为是各种工业和生物催化过程中的关键中间体。本计画主要研究钒氧化物分子团簇中高价金属氧合物与金属氢氧化物的形成、反应性与稳定性。具有预先形成的金属结合位点的金属官能化的钒氧化物[M（L）V12 O32 X]n-（= {MV 12}，M =过渡金属，L =末端配体，X =卤化物模板）被用作产生和可能稳定高价金属物质的合适模型，因为它们的氧化催化活性已经在之前被示出。特别是，该项目的重点是氧化还原活性的3d-过渡金属与多种可访问的氧化还原转换（Fe II，Mn II，CoII）作为潜在的相关模型的工业催化剂（例如哈伯-博世过程）以及酶（例如细胞色素P450）。此外，选定的4d/5d金属（RuII，IrII），因为它们可以促进高价氧代配合物的分离和结构表征。{MV 12}中金属中心的结合模式与典型的金属氧代配体（通常：具有三角配位几何结构的氮供体）有根本不同，因此可以预期具有以前未探索过的配位行为和新反应性的新中间体。在第一步中，通过现有的{MV 12}配合物与反应性配体如过氧化物和叠氮化物的反应形成高价物种，以及通过还原的{MV 12}物种活化分子氧。高价中间体的特点是使用实验和理论方法来了解它们的电子结构，结合模式和反应性。只要有可能，使用单晶X射线衍射的结构表征将提供详细的洞察结合的情况。高价物种的反应性以及它们作为催化剂的可能用途将使用合成重要的底物氧化，例如环氧化，C-H-活化和羟基化来探索。原位稳定性研究将提供对可能的簇重排或胶体形成的深入了解。因此，该项目提供了一种全新的化合物类别，其反应性可以根据形成的中间体进行合理化，并且反应性可以通过对金属中心进行化学修饰来调整。