Development of novel ligands occupying the specified positions and their application to the synthesis of new hypervalent compounds

本研究的目的是开发新的配体，利用空间和电子稳定效应占据超价主族化合物的特定位置，并利用这些配体合成具有新型骨架的超价化合物。主要是，我们已经开发了几个五配位的主族元素化合物的配体，如平面三齿配体，占据两个顶点位置和一个赤道位置，四齿配体，占据三个赤道位置和一个顶点位置，一个庞大的树枝状聚合物型的配体，占据赤道位置，和二硫代羧酸根配体的桥梁两个高度协调的主族元素。结果，我们成功地应用了四配位的1，2-碘杂环丁烷作为热稳定氧化剂，合成了三个氧原子和一个碳原子分别占据赤道和顶点位置的碳磷杂三环和碳杂硅杂三环，并合成了五配位硅原子之间和七配位硅原子之间具有键的二硅烷。我们还成功地合成了它们的相关化合物，例如含磷和铝的丙磷杂氮杂三环，具有烯烃聚合活性的阳离子硅醇合锆络合物，和迄今已知的相关卡宾中具有最高供电子能力的氨基（叶立德）卡宾。如上所述，我们利用我们自己开发的配体，通过对它们的结构、成键模式和反应性的阐明，构建了具有化学上不利构型的新型超价化合物。我们可以获得基于新结构的新知识，这将大大有助于主族化学新范式的发展。

The object of this study is to develop novel ligands, which occupy the specific positions of hypervalent main group compounds on the basis of the steric and electronic stabilization effects, and synthesize the hypervalent compounds with novel frameworks by use of these ligands. Mainly, we have developed several ligands for pentacoordinated main-group-element compounds, such as a planar tridentate ligand which occupies two apical positions and one equatorial position, tetradentate ligands which occupy three equatorial positions and one apical position, a bulky dendrimer-type ligand which occupies the equatorial position, and the dithiocarboxylato ligand which bridges two highly coordinate main-group elements. As a result, we succeeded in applying tetracoordinated 1,2-iodoxetane as a thermally stable oxidant, synthesizing carbaphosphatranes and a carbasilatrane where three oxygen atoms and one arbon atom occupy the equatorial and apical positions, respectively, and synthesizing disilanes with bonds between pentacoordinated silicon atoms and between heptacoordinated silicon atoms.In addition, we also succeeded in synthesizing their related compounds such as prophosphaalatrane containing phosphorus and aluminum, a cationic silanolatozirconium complex that has olefin polymerization activity, and an amino(ylide)carbene having the highest electron donating ability among the related carbenes known to date. As mentioned above, we achieved the construction of the novel hypervalent compounds bearing a thermodynamically unfavorable configuration by taking advantages of the ligands that we developed by ourselves and elucidation of their structures, bonding modes, and reactivities. We could obtain new knowledge based on new structures that would contribute significantly to the development of a new paradigm in main group chemistry.