Lanthanoid Transition Metal Bonding - from Unsupported Metal-Metal Bonds to the Controlled Synthesis of Highly Aggregated Systems

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Subject of the project are covalent bonds between Rare Earth Metals (RE) and Transition Metals (TM). Unsupported RE-TM bonds are difficult to access due to their high reactivity. They are highly polar or better the most polar metal-metal bonds and, thus, represent an extreme in that field of research. The reactivity of RE-TM bonds and their bond polarity allow the access to metallic RE-TM clusters. They lay in terms of chemical bonding between bimetallic complexes and the intermetallic RE-TM compounds. The latter have divers, for instance, energy technology relevant applications - high performance batteries and H2 storage materials. The state of the art in the fields of unsupported RE-TM bonds and metallic RE-TM clusters is dominated by our work since 2008. In the last (first) funding period, six manuscripts have been published and on book chapter has been submitted.The following subprojects are proposed for the second period of funding:1. Novel TM complex moieties able to form unsupported bonds to REThe identification of TM complex moieties, able to form stable unsupported bonds to RE, is essential for the further development of the research planned here and the field of polar metal-metal bonds in general. Further work is consequently based on results obtained in the first period of funding.2. Reactivity studies of RE-TM bondsIn the first period of funding, novel bismetallocenes have been prepared. They should allow a more focused study of the reactivity of RE-TM bonds. Furthermore, the reactivity of two times TM-bonded two-valent RE is of interest. 3. Generation of metallic RE-TM clusters via C-H bond activation and their supporting in nitride matrixes for catalytic applicationsThe synthesis of metallic SE-TM clusters via C-H activation has been one of the most productive subprojects of the first funding period. These investigations will be continued with regard to the systematization of the reactions and the synthesis of novel clusters. In addition, supporting of RE-TM clusters in thermally robust and chemically inert nitride matrixes is planned. The so formed hybrid materials are used as robust bimetallic heterogeneous catalysts. 4. f-Element TM multiple bondingMultiple bonding between f-elements and TM are not known but promising in a few regards. In the last 50 years, monoanionic bidentate N ligands have been successfully used to stabilize supported multiple bonds. We propose the synthesis of N ligand stabilized heterobimetallic complexes in which RE or U can form multiple bonds with TM.