Sigmatropic Rearrangement on M-E Single and Double Bond System (M = Transition Metal, E = Main Group Element

在本研究项目中，我们研究了(1)金属与主族元素之间具有不饱和键的过渡金属配合物的合成，如硅烯和二甲苯配合物；(2)不饱和键的反应性，特别是M-E和M=E键之间的异位重排（M =过渡金属，E =主族元素）。硅基（硅烯）配合物被认为是过渡金属化合物介导的有机硅化合物转化的关键中间体。然而，由于硅烯配体的缺电子性质，这种配合物太不稳定而无法分离。我们成功地利用体积较大的Mes取代基（Mes = 2,4,6- c_6h_2me_3）对硅基（硅烯）配合物进行了动力学稳定，并分离出了第一个硅基（硅烯）钨、钼和铁配合物。分离得到的硅基（硅烯）铁配合物与'BuNC反应生成二硅氧烷配合物，该配合物由1,3取代基从硅基迁移到硅烯配体，然后由1,2-硅基从铁迁移到硅烯配体。在（2-N， n -二甲氨基苯基）二甲基硅烷存在下，Cp^*W(CO)_3Me （Cp^* = η-C_5Me_5）光照射得到一个硅基配合物，其中氨基与钨原子配位。硅基配合物进一步辐照后，1,2-芳基从硅基向钨基迁移，形成碱稳定的硅基配合物。磷基硅氧烷配合物CpFe(CO)_2SiMe_2PPh_2辐照后形成了一种新型的Fe-Si-P三元环金属环配合物。由于与膦配位硅烯配体的共振形式的贡献，Fe-Si键具有不饱和性质。因此，配合物与丙酮的反应通过丙酮氧与硅炔配体的配位进行，然后插入Si-P键，形成Fe-Si-O-C-P五元环。

In this research project, we have investigated (1) synthesis of transition-metal complexes with unsaturated bonding between metal and main group elements such as silylene and germylene complexes and (2) reactivities of the unsaturated bonding, especially sigmatropic rearrangement between the M-E and M=E bonds (M = transition metal, E = main group element).Silyl(silylene) complexes have been proposed as key intermediates in many transformations of organosilicon compounds mediated by transition metal compounds. However, such complexes are too unstable to isolate due to the electron-deficient nature of the silylene ligand. We have succeeded to stabilize the silyl(silylene) complexes kinetically using bulky Mes substituents (Mes = 2,4,6-C_6H_2Me_3) and isolated the first silyl(silylene)tungsten, molybdenum, and iron complexes. Reaction of the isolated silyl(silylene)iron complex with 'BuNC afforded a disilanyliron complex produced by 1,3-substituent migration from silyl to silylene ligand followed by 1,2-silyl migration from iron to silylene ligand.Photo-irradiation of Cp^*W(CO)_3Me (Cp^* = η-C_5Me_5) in the presence of (2-N,N-dimethylaminophenyl)dimethylsilane gave a silyl complex in which the amino group was coordinated to the tungsten atom. Further irradiation of the silyl complex caused 1,2-aryl migration from silyl to tungsten to form abase-stabilized silylene complex.Irradiation of phosphinosilyliron complex CpFe(CO)_2SiMe_2PPh_2 afforded a novel metallacycle complex with Fe-Si-P three-membered ring. The Fe-Si bond bears unsaturated character due to the contribution of a resonance form with a phosphino-coordinated silylene ligand. Thus reaction of the complex with acetone proceeded via coordination of acetone oxygen to the silylene ligand followed by insertion into the Si-P bond to form a Fe-Si-O-C-P five-membered ring.