High Oxidation State Tungsten Oxo, Tungsten Thio, and Tungsten Imido Alkylidene NHC Complexes for Olefin Metathesis of Functional Olefins

制备中性和阳离子高氧化态钨氧、钨硫和钨亚胺烷基基n杂环碳（NHC）配合物，其通式为W(E)(CHCMe2R)(NHC)X2和[W(E)(CHCMe2R)(NHC)X+ Y-] （E = O， S, NR1; R1 = tBu, Ad, Ar; R = CH3, Ph）。除了用S和NR1取代氧外，还应研究具有显著不同的sigma供体能力的不同NHCs的使用。变化应包括但不限于NHC =咪唑-2-酰基，咪唑烷-2-酰基，环烷基氨基羰基（CAACs），环（氨基）（芳基）羰基（caarc），四唑啉-2-酰基，吡唑啉-4-酰基，三唑-2-酰基和r6 -碳二磷烷（R =烷基，苯基）。阴离子x配体方面，弱配体和强配体，如（氟化）烷氧化物、硫代酸盐、硫代酚酸盐和碘化物应使用。这将有助于确定E-、NHC-和x -配体对各种烯烃复分解反应的反应活性和官能团耐受性的影响。这些反应将包括闭环复分解（RCM），同质复分解，交叉复分解（CM），自复分解（SM），开环交叉复分解（ROCM）和乙烯-二炔复分解反应以及开环复分解聚合（ROMP）。在HM， SM， CM，烯-二炔和ROCM反应中，以及ROMP反应中，将特别关注立体选择性，这一问题将借助新型ansa型NHCs和具有不同sigma给体能力的NHCs来解决。特别地，研究了z选择性问题，阐明了钨环丁烷的结构（TB和SP）。本文的研究不仅拓宽了人们对钨氧/硫/亚胺烷基基NHC配合物的认识，而且为烯烃合成的C-C偶联反应提供了一类新的官能团耐受、高活性、立体和区域选择性的催化剂。最后但并非最不重要的是，我们将通过ROMP将阐述的概念应用于高度立体规则聚合物的合成。

Both neutral and cationic high-oxidation state tungsten oxo, tungsten thio and tungsten imido alkylidene N-heterocyclic carbene (NHC) complexes of the general formula W(E)(CHCMe2R)(NHC)X2 and [W(E)(CHCMe2R)(NHC)X+ Y-] (E = O, S, NR1; R1 = tBu, Ad, Ar; R = CH3, Ph) shall be prepared. Besides of the substitution of oxygen by S and NR1, the use of different NHCs with substantially different sigma-donor capability shall be investigated. Variations shall include but not be limited to NHC = imidazol-2-ylidenes, imidazolidin-2-ylidenes, cyclic alkyl aminocarbenes (CAACs), cyclic (amino)(aryl)carbenes (CAArCs), tetrazolin-2-ylidenes, pyrazolin-4-ylidenes, triazol-2-ylidenes and R6-carbodiphosphoranes (R = alkyl, phenyl). In terms of the anionic X-ligand, both weak and stronger sigma-donor ligands such as (fluorinated) alkoxides, thiolates, thiophenolates and iodide shall be used. This will allow identifying the influence of the E-, NHC- and the X-ligand on both the reactivity and functional group tolerance in various olefin metathesis reactions. These will comprise of ring-closing metathesis (RCM), homo-metathesis, cross-metathesis (CM), self-metathesis (SM), ring-opening cross-metathesis (ROCM) and ene-diyne metathesis reactions as well as of ring-opening metathesis polymerization (ROMP). In HM, SM, CM, ene-diyne and ROCM reactions, but also in ROMP, special attention will be devoted to stereoselectivity, an issue that shall be addressed with the aid of novel ansa-type NHCs and NHCs with different sigma-donor capability. In particular, the issue of Z-selectivity shall be addressed and the structure (TB vs. SP) of the tungstacyclobutane shall be elucidated. The work proposed here is not only intended to broaden the understanding about tungsten oxo/thio/imido alkylidene NHC complexes, but also to offer a new class of functional group tolerant, highly active, stereo- and regioselective catalysts for olefin metathesis-based C-C coupling reactions. Last but not least, we will apply the elaborated concept to the synthesis of highly stereoregular polymers via ROMP.