Functional Group Tolerant Olefin Metathesis Catalysts Based on N-Heterocyclic Carbene Complexes of High Oxidation State Molybdenum Imido Alkylidenes

应制备高氧化态Mo-亚氨基亚烷基的N-杂环卡宾(NHC)加合物。为此，应使用不同的 NHC，即小、大、强碱性或亲核 NHC。催化剂结构的变化应进一步包含不同的阴离子配体，例如醇盐、酚盐、羧酸盐、异(硫)氰酸盐以及不同的酰亚胺配体。所选择的方法将能够阐明 NHC 对亚烷基金属在配体解离和伴随形成的阳离子亚烷基物种方面的活化作用。此外，还将阐明阴离子配体的作用。值得注意的是，具有混合阴离子配体的金属配合物是可以获得的。就使用新系统的不同类型的复分解反应而言，我们希望解决与有机合成和聚合物化学相关的烯烃复分解反应。这些反应包括闭环复分解（RCM）、交叉复分解（CM）、开环交叉复分解（ROCM）烯炔/烯-二炔复分解和自复分解（SM）反应以及开环复分解聚合（ROMP）、无环二烯复分解（ADMET）聚合和二炔环聚合。使用离子催化剂，所有设想的反应类型，包括聚合反应，都可以在双相条件下进行。除环化聚合外，还可以应用连续负载离子液体相 (SILP) 条件。在 CM、烯炔和 SM 反应中，以及在 ROMP 和环聚合中，将特别关注立体选择性。这项工作不仅将拓宽对高氧化态金属亚烷基NHC配合物的理解，而且还将为基于烯烃复分解的C-C偶联反应提供一类新型的官能团耐受性、高活性立体和区域选择性催化剂。

N-Heterocyclic carbene (NHC) adducts of high oxidation state Mo-imido alkylidenes shall be prepared. For these purposes, different NHCs, i.e. small, large, strongly basic or nucleophilic ones, shall be used. Variations in catalyst structure shall further comprise of different anionic ligands such as alkoxides, phenoxides, carboxylates, iso(thio)cyanates as well as of different imido-ligands. The chosen approach will allow elucidating the activating effect of the NHC on the metal alkylidene in terms of ligand dissociation and concomitant formation of cationic alkylidene species. Furthermore, the role of the anionic ligands will be elucidated. Notable, metal complexes with mixed anionic ligands are accessible. In terms of different types of metathesis reactions for which the novel systems shall be used, we wish to address olefin metathesis reactions relevant to both organic synthesis and polymer chemistry. These will comprise of ring-closing metathesis (RCM), cross-metathesis (CM), ring-opening cross metathesis (ROCM) enyne / ene-diyne metathesis and self-metathesis (SM) reactions as well as of ring-opening metathesis polymerization (ROMP), acyclic diene metathesis (ADMET) polymerization and the cyclopolymerization of diynes. With ionic catalysts, all the envisaged reaction types including polymerization reactions can be carried out under biphasic conditions. With the exception of cyclopolymerization, continuous supported ionic liquid phase (SILP) conditions can be applied. In CM, enyne and SM reactions, but also in ROMP and cyclopolymerization, special attention will be devoted to stereoselectivity. The proposed work will not only broaden the understanding about high oxidation state metal alkylidene NHC complexes, but also offer a new class of functional group tolerant, highly active stereo- and regioselective catalysts for olefin metathesis-based C-C coupling reactions.