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上，因为它们的低放射性使这些离子适合于从基本配位和有机金属化学到催化和材料科学的实际应用。在本提案中，我们设想现在开发新的定制配体，它们与低价，中价和高价铀的配位化学，以及这些配位配合物在对硫活化的反应性研究中的应用。在我们小组之前和发表的工作中，我们可以证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，可以观察到单质硫和硒以及杂烯，如二硫化碳和羰基硫化物的活化。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，以激活元素硫原，以合成多硫族化合物桥接的配合物，这些配合物是由各种大小的环和链引起的。项目合作伙伴将用最先进的光谱和理论方法研究这些复合物。进一步的反应性研究，包括原子和基团转移反应、硫族化合物的去除、小分子的活化、氧化还原和电化学等，将为合成配合物的反应性和电子结构提供进一步的见解。从基础研究的角度来看，含有硬铀离子和软硫、硒和碲配体的配合物对于推进对金属配体键共价的理解至关重要，这对于镧系/锕系分离方法的发展或未来的新催化体系至关重要。

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.