Activation of Chalcogens by Uranium Centers - Reactivity Control via Ligand Architecture

在过去的几十年里，锕系元素的无水化学是一个活跃的研究领域。这些研究活动主要集中在铀和钍的化学方面，因为它们的低放射性使这些离子适合于实际应用，从基本配位和有机金属化学到催化和材料科学。在这个建议中，我们设想现在的发展新的量身定制的配体，它们的配位化学与低，中，高价铀，和应用这些配位络合物的反应性研究对硫族元素活化。在我们小组以前和已发表的工作中，我们可以表明，我们的签名螯合配体可以在铀介导的还原转化中作为非常有效的支持配体，可以观察到元素硫和硒以及杂联烯（如二硫化碳和硫化羰）的活化。基于这些发现，我们建议在这个联合研究项目中进一步开发我们现有的配体系统，以激活元素硫族元素，用于合成多硫族化合物桥连的络合物，这是由连接到各种大小的环和链产生的。这些复合物将由项目合作伙伴通过最先进的光谱和理论方法进行研究。进一步的反应性研究，包括原子和基团转移反应、硫属化物的去除、小分子的活化、氧化还原和电化学等，将提供进一步的洞察力的反应性和合成的配合物的电子结构。从基础研究的角度来看，含有硬铀离子和软硫、硒和碲配体的络合物对于促进对金属配体键中的共价性的理解是根本重要的，这对于镧系元素/锕系元素分离方法或未来的新催化体系的开发是必不可少的。

During the last decades, the anhydrous chemistry of actinides was an active field of research. These research activities have mainly focused on the chemistry of uranium and thorium because their low radioactivity renders these ions suitable for use in practical application, ranging from fundamental coordination and organometallic chemistry to catalysis and material science. In this proposal, we envisage now the development of new tailor-made ligands, their coordination chemistry with low-, mid-, and high-valent uranium, and the application of these coordination complexes in reactivity studies towards chalcogen activation. In previous and published work of our groups we could show that our signature chelating ligands can act as very efficient supporting ligands in uranium-mediated reductive transformations, activation of elemental sulfur and selenium as well as heteroallenes, like carbon disulfide and carbonyl sulfide, could be observed. Based on these findings we propose in this joint research project to develop our existing ligand systems further in order to activate the elemental chalcogens for the synthesis of polychalcogenide-bridged complexes, which result from catenation to rings and chains of various sizes. These complexes will be studied by state-of-the-art spectroscopic and theoretical methods by the project partner. Further reactivity studies, including atom and group transfer reactions, removal of chalcogenides, activation of small molecules, redox and electrochemistry, etc., will provide further insight in the reactivity and electronic structures of the synthesized complexes. From a fundamental research point of view, complexes containing the hard uranium ion and soft sulfur, selenium, and tellurium ligands are fundamentally important to advance understanding of covalency in the metal ligand bond that is essential for the development of lanthanide/¬actinide separation methodologies or future, new catalytic systems.