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

制备高氧化态钼-亚胺基烷基烷的N-杂环卡宾(NHC)加合物。为此目的，应使用不同的NHC，即小型、大型、强碱性或亲核的NHC。催化剂结构的变化还应包括不同的阴离子配体，如醇盐、苯氧化物、羧酸盐、异硫氰酸酯以及不同的亚胺配体。所选择的方法将有助于阐明NHC对金属亚烷基的活化作用，即配体解离和阳离子亚烷基物种的伴随形成。此外，阴离子配体的作用将被阐明。值得注意的是，具有混合阴离子配体的金属络合物是可以访问的。就不同类型的歧化反应而言，我们希望解决与有机合成和聚合物化学有关的烯烃歧化反应。这些反应包括开环复分解反应(RCM)、交叉复分解反应(CM)、开环交叉复分解反应(ROCM)、烯炔/烯二炔复分解反应和自复分解反应(SM)，以及开环复分解聚合(ROMP)、非环二烯复分解(ADMET)聚合和双炔的环聚反应。有了离子催化剂，所有设想的反应类型，包括聚合反应，都可以在两相条件下进行。除环聚合外，可应用连续支撑离子液体(SILP)条件。在CM，enyne和SM反应中，也在ROMP和环聚反应中，将特别注意立体选择性。这些工作不仅拓宽了人们对高氧化态金属亚烷基NHC络合物的认识，而且为烯烃歧化C-C偶联反应提供了一类新型的可耐官能团、高活性、立体选择性和区域选择性的催化剂。

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.