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

本研究项目旨在合成具有桥联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合成了具有桥联硅烯配体的双核Pd和Pt配合物。例如，铂(PCy_3)_2可以方便地作为双核铂(I)与两个桥联硅基配体的配合物的前体。从Pd(O)和Pt(O)的混合物中还得到了桥联二苯基硅基配体的异双核Pd-铂配合物。双膦配体与双核配合物反应生成了铂配合物和铂3Pd配合物。这些化合物的分子结构已通过X射线结晶学和溶液的详细核磁共振测量得到了揭示。得到的配合物具有四个铂(O)或钯(O)中心，通过桥联硅烯配体和金属-金属键连接。键长和键角显示出高度对称的平面结构。密度泛函理论计算表明，四核核由零价金属中心和中性硅烯配体组成。还合成了桥联二芳基锗配体的类似钯配合物，并对其进行了表征。上述反应形成了四核配合物。该反应是由单齿膦配体与螯合双膦配体交换引起的。随后双核配合物的缩合伴随着硅基配体转化为硅烯配体或Germyl配体转化为双烯配体，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.