Activation And Transformation Of Small Molecules Containing Nitrogen Mediated By Thiolate-Bridged Bimetallic Complexes

In this thesis,using thiolate-bridged bimetallic complexes as functional platform,we realizedthe activation and transformation of nitrosobenzene and nitrogen oxides by metal-metal or metal-ligand cooperation effect.It provides important experimental support for understanding the reductive metabolism of nitrosobenzene,nitrate and nitrite in the biological system at the molecular level.Moreover,we also investigated the reactivity of thiolate-bridged diiron complex with cyanides and successfully constructed a series of novel thiolate-bridged anionic isocyanide diiron complexes.Firstly,we synthesized the first diiron benzenesulfinamide-bridged complex by the reaction of[Cp*Fe（μ-η²:η⁴-bdt）FeCp*][PF₆]with nitrosobenzene.In this process,the thiolate ligand serves as electron donors for the four-electron reduction of nitrosobenzene and the iron centers play as electron shuttle mediator.In addition,this thiolate-bridged diiron system can efficiently catalyze the reduction of nitrosobenzene to aniline under mild conditions.The results of further studies demonstrated that,compared to the intact bridging nitrosobenzene ligand,the benzenesulfinamide ligand has priority to convert into aniline,which may imply the formation of the sulfinamide species accelerates the reduction process of nitrosobenzene.This provides experimental support for understanding the reductive metabolism of nitrosoarene in biological system.Secondly,we investigated the activation and functional transformation of nitrogen oxides such as NO₃^-,NO₂^-and NO by mono-or bidentate thiolate-bridged diruthenium complexes.[Cp*Ru（μ-SEt）（MeCN）]₂[PF₆]₂reacted with NO₃^-and NO₂^-to obtain diruthenium nitrate and nitrite complexes,respectively.Among them,nitrate complex is quite stable and difficult to realize the reduction in the presence of protons and electrons,while nitrite complex can realize a continuous conversion process of NO₂^-→NO→N₂O as observed in the late stage of the denitrification process.[Cp*Ru（μ-η²:η⁴-bdt）RuCp*]reacted with NO₃^-to afford a non-chelated nitrate complex,which can simulate a continuous reduction process of NO₃^-→NO₂^-→NO as observed in the early stage of the denitrification process.The above two systems provide new functional models for understanding the denitrification process in nature at the molecular level.Thirdly,[Cp*Fe（μ-SEt）（MeCN）]₂[PF₆]₂ was used as a reaction platform for exploring the activation and functionalization of cyanide.When KCN was used as cyanide source,a facile salt metathesis occurred to generate monocyanide or dicyanide species.However,using trimethylsilyl cyanide as the cyanide source,an anionic nitrile complex with[CNSiMe₃]^-group was obtained by the activation of one non-coordinating anion.Furthermore,using the active group[CNSiMe₃]^-as the reaction site,a series of anionic isocyanide complexes were generated by the interaction with the counter anions in the outer sphere.Finally,a series of novel halogen-bridged trinuclear metal complexes containing cup-shaped sulfur-nitrogen ligand were designed and synthesized.In these complexes,metals and halogens alternately connected to form a structural unit featuring chair-type six-membered ring configuration,which is located in the cavity of cup-shaped ligand.Furthermore,the effect of steric hindrance of the cup-shaped ligand on the structure of polynuclear complexes was also investigated.The experimental results show that when the steric hindrance of the ligand increases,a similar trinuclear structure cannot build,instead of forming a butterfly-type{Co₂Cl₂}binuclear complex.