The Effect Of Axial Ligands On Rh 2 (esp) 2 And The Construction Of Heterogeneous Catalysts And Their Application In The Synthesis Of NH Heterocyclopropane Compounds

Dirhodium complexes are unique di-metal compounds,which may shows different catalysis activities from single metal compounds in organic reactions due to their metal-metal bounds between the two metal centers.With axial ligands modification,the activities of dirhodium compounds can be fine-tuned,which would improve the dirhodium?II?catalyst catalytic activity and selectivity in some reactions.This thesis mainly study the influence of the axial ligands effecting the dirhodium compounds in organic reactions.Dirhodium?II?complexes is also a kind of precious metal compounds.In large scale of homogeneous reaction,it may be resulting in the loss of precious metals and environmental pollution.According to viewpoints of energy and materials saving,diminishment of pollution,and environmental protection based on“Green Chemistry”,it proved easier and more efficient to separate heterogeneous catalysts from reaction system and reuse them in comparison with the corresponding homogeneous catalysts,which could reduce cost of products and also reduce the environmental pollution,such as deleterious heavy metallic ions and harmful organic substance.It consists of two parts:one part is axial ligands coordination on Rh₂?esp?₂and used to synthesis of N-H aziridines from olefins.The another part is one-pot synthesis of ZIF-8 with Rh₂?esp?₂ and their applications for synthesis of N-H aziridines from olefins.1.In order to solve the low yield and selectivity of some reaction in synthesis N-H aziridine.We found axial ligands of containing N?i.e.Imidazole,2-Methylimidazole,2,4-dimethylimidazole?can easily coordinate with dirhodium?II?Complexes.And the ligand will change electron distribution around the dirhodium?II?after coordination,which would improve the catalytic activity and selectivity of Rh₂?esp?₂ in catalytic synthesis N-H aziridine.Then we confirmed the formula through single crystal of axial ligands and Rh₂?esp?₂ after coordination.We used the new Dirhodium?II?catalyst to catalytic synthesis three different types of N-H aziridines and all can obtain higher selectivity and yield than single Rh₂?esp?₂ complexes.2.In order to reduce the loss of precious metals and protect environment,we design one-pot preparation of Rh₂?esp?₂@ZIF-8 catalyst through the coordination-driven encapsulation approach,which firstly obtained the immobilized Rh₂?esp?₂ catalyst with high loading and catalytic reactivity.Next,we used the Transmission electron microscopy?TEM?,X-ray powder diffraction?XRD?,X-ray photoelectron spectroscopy?XPS?to characterize.In this part,the axial ligands have played a vital role.It can simply modify the Rh₂?esp?₂ after coordination.Meanwhile,Rh₂?esp?₂complexes can be grafted on ZIF-8 materials through 2-methylimidazole groups.The heterogeneous catalyst showed highly active in catalytic synthesis N-H aziridine and can be recycled four times without losing its high selectivity and yield.