Chemistry of open-shell metal complexes: Tuning spin density distributions between P-ligands and metals

由于目前关于开壳p配体金属配位化学的知识匮乏，本项目将努力获得新的基础见解。我们想要探索两类氧化还原活性阴离子p配体的氧化SET反应，根据形式电荷位置进行分类，即在磷或邻近的杂原子（如O或n）上。配体中心反应应产生具有不同电子自旋密度分布的三重态自由基；后者由本项目的两条主要研究线A和B来解决。此外，在b部分，N-O键均解将被确立为可行的途径。这些自由基的不同反应机会将通过改变阴离子配合物前体的取代模式以及所使用的氧化SET试剂的性质来揭示：有机氧化剂可能提供干净的捕获机会，而无机氧化剂可能开辟全新的途径。为了研究和调节金属电子组态对自旋密度分布的影响，我们将对相关的6-10族金属配合物的金属配合物碎片在这些自由基成键中的作用进行比较研究。中间体将通过循环伏安法（与R. boer<s:1>合作）、EPR、核磁共振或低温红外光谱进行研究，理论支持将加深对键合的见解（与A. Frontera和Z.-W合作）。曲)。该研究项目的长期目标是确定金属p配体在氧化还原反应中的协同作用的基本方面，同时也有助于为自由基催化的应用做准备。

Due to the scarcity in knowledge about metal coordination chemistry of open-shell P-ligands, this project will endeavor to achieve new fundamental insights. We want to explore oxidative SET reactions of two classes of redox-active anionic P-ligands, categorized according to the formal charge location, i.e., at phosphorus or an alpha-neighbouring heteroatom such as O or N. The ligand-centered reactions shall generate triplet radicals that possess different electron spin density distributions; the latter is addressed by the two main research lines A and B of this project. Additionally, N-O bond homolysis will be established as viable route in part B. The different reaction opportunities of such radicals shall be disclosed by varying the substitution pattern of the anionic complex precursors as well as by the nature of the employed oxidative SET reagents: organic oxidants may provide clean trapping opportunities, whereas inorganic oxidants may open entirely new pathways. The role of the metal complex fragment in the bonding of such radicals will be comparatively studied for related group 6-10 metal complexes in order to study and modulate the influence of the metal electron configuration on the spin density distribution. Intermediates will be investigated by cyclic voltammetry (collaboration with R. Boeré), EPR, NMR or IR spectroscopy at low temperatures, and theoretical support will deepen insights into the bonding (collaboration with A. Frontera and Z.-W. Qu). The long-term goal of this proposed research project is to identify fundamental aspects of interest for metal P-ligand cooperativity in redox reactions, but also help preparing for applications in radical catalysis.