Ligand Replacement—An Efficient Strategy For Synthesizing Iron-sulfur Clusters Of Nitrogenase-related Heteroligands

Molybdenum nitrogenase can convert ammonia gas to ammonia under mild conditions in azotobacter.The active center of nitrogenase(iron-molybdenum-coenzyme)is a weak-field complex with an internal core cluster[MoFe7S9C].This hetrometallic iron-sulfur cluster consists of two moieties[Fe4S3]and[MoFe3S3C]which was bridginged by the terminal sulfur atoms and six coordinated carbon atom.Simulation of FeMo-cofactor structure by chemical synthesis methods has always been one of the most important challenges in bioinorganic chemistry.In order to solve this synthesis problem,chemists explored many synthetic strategies and methods.We have introduced the development of synthesis strategies and related clusters that were been synthesized.Furthermore,a novel synthesis strategy is put forward to develop synthetic exploration.My research consisted of two issues under the thesis that is related to the new strategy and the synthesis of clusters.On the basis of template-assisted assembly,an entirely new core ligand replacement strategy was introduced.Firstly,halogen bridged cuboidal structure iron-sulfur cluster([(Tp*)WFe1S3Q3]z)was synthesized.The bridge site is a halogen atom.The introduction of a metrologically controlled reducing agent benzophenone sodium carbonyl radical solution modulates the equivalent of halogens and reducing agents turn out a high yield from the template compound[(Tp*)WS3]1-.Incomplete cubane halogen bridged clusters was treated as precursors,through the method of direct ligand substitution,azide,methoxide,mercaptan and thiophenol bridged incomplete cubane type clusters were synthesized.Lighter atoms such as N and O that were firstly introduced into the system at the core bridging position of the heterometal heteroleptic incomplete cubane type iron-sulfur clusters core.The cubane type halogen bridged iron-sulfur clusters([(Tp*)WFe3S3Q4]z)were synthesized under the guidance of the above strategies that regulate the reducing agent benzophenone sodium carbonyl radicals and iron sources to precisely controlling halogens and electrons.When halogen-bridged cubane type clusters were used as precursors,ligand replacement strategies by redox atoms were introduced.Oxidizing donors such as TMS-N3,S8 were introduced to the reactions to utilize the strong reducibility of the cubane type precursors.The strong reducibility of the compounds results in the replacement of triple bridged ligands clusters[(Tp*)WFe3S3(μ3-Q)Cl3]z(Q = Me3SiN2-,S2-);this strategy gave further possibility to the synthesis of nitrogenase related clusters.The cluster[(Tp*)WFe3S3(μ3-Ntms)Cl3]1-,one of the very few instances of a synthetic Fe-S cluster containing a light atom(C,N,O)in the core,which constitutes the first close mimic of the[MoFe3S3C]fragment in FeMo cofactor.Superposition of them and comparison of metric information disclose a clear structural relationship...