Synthesis of Tetranuclear Complexes of Pd and Pt with Planar Structures and Development of Their Functionalities

本课题旨在合成具有桥接二芳基硅烯配体的新型四核铂钯配合物，并确定其独特的平面结构。用本课题组和美国课题组报道的方法制备了带有桥接硅烯配体的双核Pd和Pt配合物。例如，Pt(PCy_3)_2作为具有两个桥接硅基配体的双核Pt(I)配合物的方便前体。Pd(O)和Pt(O)配合物的混合物也可得到带桥接二苯基硅基配体的杂二核Pd-Pt配合物。螯合二膦配体与双核配合物反应得到Pt_4配合物和Pt_3Pd配合物。这些配合物的分子结构已通过x射线晶体学和详细的核磁共振测量揭示。所得到的配合物有四个Pt(O)或Pd(O)中心与桥接硅烯配体和金属-金属键结合。键长和键角表明配合物具有高度对称的平面结构。配合物的DFT计算表明，四核核心由零价金属中心和中性硅烯配体组成。具有桥接二芳基二甲苯配体的类似钯配合物也被制备和表征。上述反应，形成四核配合物，已被核磁共振波谱跟踪。该反应是由单齿膦配体与螯合的二膦配体交换引起的。随后的双核配合物的缩合伴随着硅基配体转化为硅烯配体或胚基配体转化为二烯配体，从而形成四核配合物。

This research project aims to synthesize novel tetranuclear platinum and palladium complexes having bridging diarylsilylene ligands and to determine the unique planar structures. Dinuclear Pd and Pt complexes with bridging silylene ligands are obtained with the procedure Which were reported by our group as well as the research group in the States. For example, Pt(PCy_3)_2 functions as a convenient precursor of the dinuclear Pt(I) complexes with two bridging silyl ligands. Heterodinuclear Pd-Pt complex with bridging diphenylsilyl ligand is also obtained from a mixture of Pd(O) and Pt(O) complexes. Reaction of a chelating diphosphine ligand with the dinuclear complexes afforded the Pt_4 complexes and Pt_3Pd complexes. The molecular structures of these complexes have been revealed by X-ray crystallography and by detailed NMR measurement of the solutions. The obtained complexes have four Pt(O) or Pd(O) centers bonded with bridging silylene ligands and metal-metal bonding. Bond lengths and angles show high symmetrical planar structures of the complexes. The DFT calculation for the complexes revealed that the tetranuclear core consists of the zero valent metal centers and neutral silylene ligands. Analogous Pd complexes with bridging diarylgermylene ligands have also been prepared and characterized.The above reaction, forming the tetranuclear complexes, has been followed by the NMR spectroscopy. The reaction is induced by exchange of the monodentate phosphine ligand with the chelating diphosphine ligand. The subsequent condensation of the dinuclear complexes accompanies conversion of the silyl ligand to silylene ligand or germyl ligand to digermene ligand, which leads to formation of the tetranuclear complexes.