d-pi Interaction in Transition Metal Cluster Complexes and Their Properties

本文合成了铑、铱与芳香族或氯代桥联配体的过渡金属簇合物，研究了它们的结构和物理化学性质，得到以下结果.双核铑配合物与氯硅烷反应，得到了新型的含氯桥的四核铑配合物。基于X射线结构和密度泛函理论计算，铑双核配合物的单占据分子轨道（SOMO）的对称性和离域性严重依赖于配体。在<RhRh>Rh_2^&lt;5+&gt;轴向膦配体配合物中观察到σ_p和n_p轨道的大混合。π_<RhRh>* 轨道定域在金属原子上，而π_* 轨道适度离域在桥连配体的π系统上.具有桥联氨基吡啶配体的二铱配合物具有较低的氧化电位和较短的金属-金属分离. Rh_2^&lt;5+&gt;与羟基吡啶配合物的δ ~* SOMO离域到芳族桥联配体上的程度约为10%。在晶体中，Rh_2^&lt;4+&gt;和Rh_2^&lt;5+&gt;配合物中填充了π堆积排列的芳香族桥联配体。某些Rh_2^&lt;5+&gt;配合物的电导率在10^<-7>S cm^<-1>（室温，小球）的数量级。分析了芳香族桥联配体Rh_2^&lt;5+&gt;配合物晶体的磁性与晶体结构的关系.正方形平面Pd（II）和Pt（II）与甲硅烷基或甲锡烷基和膦配体的配合物显示出容易的扭转旋转单分子异构化。

Transition metal cluster complexes of rhodium and iridium with aromatic or chloro bridging ligands have been prepared, their structure and physicochemical properties have been studied and following results have been obtained.1. The reaction of dinuclear rhodium complexes with silyl chlorides gave new type of tetranuclear rhodium complexes with chloro-bridges.2. The symmetry and delocalization of the singly occupied molecular orbitals (SOMO) of rhodium dinuclear complexes were shown to be heavily dependent on ligands based on X-ray structures and DFT theoretical calculations. A large mixing ofsiguma_<RhRh> and n_p orbitals were observed for Rh_2^<5+> complexes with axial phosphine ligands. The pi_<RhRh>* orbital is localized on the metal atoms and the orbital is moderately delocalized onto the pi system of the bridging ligands.3. Diiridium complexes with bridging aminopyridine ligands were shown to have low oxidation potentials and short metal-metal separations.4. The delta* SOMO of Rh_2^<5+> complexes with hydroxypyridine ligands were shown to be delocalized onto the aromatic bridging ligands to the extent of about 10 %. In crystal, Rh_2^<4+> and Rh_2^<5+> complexes were packed with pi stacked arrangement of aromatic bridgeing ligands. Electric conductance of some of Rh_2^<5+> complexes were in the order of 10^<-7> S cm^<-1> (room temperature, pellets). Magnetism of crystals of Rh_2^<5+> complexes with aromatic bridging ligands were analyzed in relation to their crystal stucture.5. Square planar Pd(II) and Pt(II) complexes with silyl or stannyl and phosphine ligands showed facile twist-rotational unimolecular isomerization.