Development of Novel Transformation Reactions of Silicon Compounds Utilizing Specific Reactivity of Transition Metal-Silylene Complexes

通过用大体积甲酰基稳定的硅基（硅烯）配合物进行机理研究，证明了在温和条件下，取代基从硅基配体向硅烯配体的1,3迁移和硅基配体从金属向硅烯配体的1,2迁移是可逆的。我们还发现在一些钨配合物中芳基配体在金属中心和硅烯配体之间可逆迁移。利用大体积烷基的空间保护作用，合成并稳定了一种硅烯配体上有氢的硅烯钨配合物，并首次成功地确定了该类配合物的晶体结构。这种晶体结构分析表明，氢化物配体桥接在钨硅双键上。该氢硅烯配合物可与各种极性有机分子如腈、酮、烯酮、甲醇等反应生成硅氢化、[4+2]cy、更多的氯加成等产物。通过这些研究，我们证明了在一些硅烯配合物上，金属-硅双键在诱导特定的相互作用和重排方面起着重要的作用，并在硅化合物上引起了新型的化学转化。首次合成了由硅、磷、铁组成的三元金属环，并对其结构、重排反应、二聚化反应以及与各种极性分子的反应进行了研究。这些反应都伴随着硅磷键的解理，可能是因为在这些金属环中，典型形式的磷化物（硅烯）配合物的贡献很大，导致硅磷键的强极化，并且环应变激活了键。在含硫或含碲而不是含磷的体系中也观察到类似的金属环形成和反应，而在含氮的体系中，发现发生了一个有趣的反应，涉及氨基硅基配体迁移到负原子上。少

Through the mechanistic studies using silyl(silylene) complexes stabilized by bulky mesityl groups, we proved that the 1,3-migration of a substituent from the silyl ligand to the silylene ligand and the 1,2-migration of the silyl ligand from the metal to the silylene ligand proceed reversibly under mild conditions. We also found that an aryl ligand migrates reversibly between a metal center and a silylene ligand in some tungsten complexes. With the help of steric protection of a bulky alkyl group, we synthesized and stabilized a silylenetungsten complex having a hydrogen on the silylene ligand, and succeeded in determining the crystal structure for the first time for this type of complex. This crystal structure analysis revealed that a hydride ligand bridges over the tungsten-silicon double bond. This hydrosilylene complex was found to react with various polar organic molecules such as nitriles, ketones, enones, and methanol to give the products formed through hydrosilylation, [4+2] cy … More cloaddition, etc. By these researches, we demonstrated that, on several silylene complexes, the metal-silicon double bond plays an important role to induce specific interactions and rearrangements, and causes new types of chemical conversions on silicon compounds.Three-membered metallacycles composed of silicon, phosphorus, and iron were first synthesized, and the structure, rearrangement reaction, dimerization reaction, and reactions with various polar molecules were investigated. These reactions all proceeded accompanied by the cleavage of the silicon-phosphorus bond, probably because, in these metallacycles, contribution of the canonical form of phosphide(silylene) complex is substantial and causes strong polarization of the silicon-phosphorus bond, and also the ring strain activates the bond. An analogous formation and reactions of metallacycles were also observed in the systems containing sulfur or tellurium instead of phosphorus, whereas in the system containing nitrogen, an interesting reaction involving migration of the aminosilyl ligand onto a negative atom was found to occur. Less