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

本课题主要研究了（1）金属与主族元素之间存在不饱和键的过渡金属配合物的合成，如硅烯配合物和锗烯配合物;（2）不饱和键的反应性，特别是M-E键和M=E键之间的σ迁移重排反应（M =过渡金属，E =主族元素）硅烷基（亚硅烷基）配合物被认为是过渡金属化合物介导的许多有机硅化合物转化反应的关键中间体。然而，由于亚甲硅烷基配体的缺电子性质，这种络合物太不稳定而不能分离。我们成功地用大体积的Mes取代基（Mes = 2，4，6-C_6H_2Me_3）使硅（亚硅基）配合物动力学稳定，并分离出第一批硅（亚硅基）钨、钼和铁配合物。分离的甲硅烷基（亚硅基）铁与BuNC的配合物通过1，3-取代基从硅基向亚硅基配体的迁移和1，2-硅基从铁向亚硅基配体的迁移得到二硅基铁配合物（Cp^* = η-C_5Me_5）（2-N，N-二甲氨基苯基）二甲基硅烷与钨原子配位，得到了氨基与钨原子配位的硅烷基配合物。进一步辐照硅基配合物，使1，2-芳基从硅基向钨基迁移，形成碱基稳定的硅烯配合物，再辐照膦基硅铁配合物CpFe（CO）_2SiMe_2PPh_2，得到一种新型的含Fe-Si-P三元环的金属配合物。Fe-Si键具有不饱和特征，这是由于与膦基配位的亚甲硅烷基配体的共振形式的贡献。因此，配合物与丙酮的反应通过丙酮氧与硅烯配体配位，然后插入Si-P键形成Fe-Si-O-C-P五元环来进行。

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.