Ligand-Metal Electron Transfer Processes in Complexes of Late Transition Metals with Redoxactive Guanidine Ligands: Fundamental Understanding and Applications in Redox Catalysis

具有氧化还原活性配体的配位化合物目前正在深入研究，因为配体氧化还原活性产生了额外的可能性。在催化应用中，氧化还原活性配体可以作为电子储层来提高底物的活性。此外，氧化还原活性配体通常以自由基配体的形式存在，并且配体上增加的自旋密度导致了特殊的、以配体为中心的反应性。最后，直接与氧化还原活性配体结合的金属的性质（例如刘易斯酸度）随着氧化还原活性配体的氧化还原状态而变化。我的课题组研究具有氧化还原活性胍配体的配位化合物。这些配体可分为两类，一类是由两个或多个胍基直接连接到芳香核上的胍基功能化芳烃（gfa），另一类是由两个胍基（或相关基）通过N-N键直接连接在一起的脲嘧啶及其相关化合物。这两个复合类都与计划的研究相关。该项目由TP1和TP2两个子项目组成。各种不同刺激物对分子内电子转移过程的定向刺激是TP1的主要主题。与第一个资助期集中于较小的双胍和四胍配体不同，由两个或多个电子偶联的氧化还原活性单元构成的氧化还原活性低聚胍被纳入研究。TP1的基础研究为TP2在键活化和与氧化还原活性胍配体配合物的催化应用方面的一些工作奠定了基础。此外，在TP2中研究了游离氧化还原活性胍与质子耦合的电子转移反应。

Coordination compounds with redox-active ligands are currently intensively studied, due to the additional possibilities that arise from ligand redox-activity. A redox-active ligand could act as electron reservoir to enhance substrate activation in catalytic applications. Moreover, redox-active ligands often are present as radical ligands, and the increased spin density on the ligand leads to a special, ligand-centered reactivity. Finally, the properties (e.g. Lewis acidity) of a metal directly bound to a redox-active ligand change with the redox state of the redox-active ligand. My research group studies coordination compounds with redox-active guanidine ligands. These ligands could be devided into two classes, the Guanidino-Functionalized Aromatics (GFAs), consisting of two or more guanidino groups directly attached to an aromatic core, and the urea azines and related compounds, consisting of two guanidinyl groups (or related groups) that are directly connected to each other via an N-N bond. Both compound classes are of relevance for the planned studies. The project is composed of two sub-projects, TP1 and TP2. The directed stimulation of intramolecular electron-transfer processes by a variety of different stimulants is the main topic in TP1. In difference to the first funding period that concentrated on preferably small bis- and tetrakisguanidine ligands, redox-active oligoguanidines, built of two or more electronically coupled redox-active units, are included into the studies. The fundamental studies in TP1 are the basis for some of the work in TP2 on bond activations and catalytic applications with coordination compounds with redox-active guanidine ligands. Moreover, proton-coupled electron transfer reactions with free redox-active guanidines are studied within TP2.