Theoretical Investigation On The Activation Of C-C Bonds And C-H Bonds In Ethene By Rare Earth Metals La And Actinide Metals U In Gas Phase

In recent years,people have discovered through extensive experiments that transition metals can be used as catalysts for many reactions.In particular,as a catalyst for chemical reactions involving organic small molecules,many chemical workers have drawn eager attention.Numerous studies have shown that transition metal catalyzed reactions of organic small molecules often have the phenomenon that the ground states of reactants and products are different spin states,that is,such reactions are two-state or multiple-state reactions that do not obey the law of conservation of spin(TSR/MSR).In order to deeply explore the microscopic mechanism of this type of reaction,to achieve the target reaction with high selectivity and to avoid the occurrence of side reactions,the chemists conducted a lot of experimental research and theoretical exploration.Due to the fact that the electrons in the d orbital of the transition metal are not filled up and the ground state is mostly in a high spin state,it is easy to undergo intersystem crossing in the catalytic reaction process,resulting in potential energy planes of different spin states.There is a cross between,that is,spin flipping occurs.Therefore,understanding the reaction mechanism of transition metal catalyzed organic small molecules can provide important mechanistic information for the study of similar reactions,which is extremely meaningful for understanding such reactions.Based on the basic theory and basic methods such as Density Functional Theory(DFT),Natural Bond Orbit(NBO)theory,and Density of State(DOS)analysis in quantum chemistry,this paper uses the procedures of Gaussian 09 and Multiwfn to Rare Earth Metals Lanthanum-Catalyzed dehydrogenation and the coupling of C-C bonds of ethylene molecules in the gas phase and the reaction of Actinide Metals U the Activation of C-H Bonds in Ethylene molecules have been systematically studied theoretically,the geometry of all reactants,intermediates and transition states in the reaction system was optimized,and the stable configuration and energy information of each stagnation point were obtained.Using electronic localization function(ELF),atoms in molecules(AIM)and natural bond orbital(NBO)theory etc.methods were used to analyze the structure of various stagnation points in the reaction process,and the density of states(DOS)and orbital composition of important intermediates wereanalyzed.Finally,the reaction mechanism was determined.The full text consists of four chapters.In the first chapter,we briefly introduced the development background and application of quantum chemistry,summarized the theory of two-state reaction and polymorphism and its research progress,finally,the main contents of this article's research work are summarized.In the second chapter,we mainly introduce basic assumptions of quantum forces,density functional theory,reaction potential energy surface,transition state theory,intrinsic reaction coordinate theory,density of states,and atoms in molecules theory.These basic theories and basic methods have laid a solid theoretical foundation for the third and fourth chapters of this paper.In the third chapter,we use the B3 LYP method in density functional theory to study the microscopic mechanism of the Rare Earth Metals Lanthanum-Catalyzed dehydrogenation and the coupling of C-C bonds of ethylene molecules in the gas phase.The full-parameter optimization analysis and energy calculation of the reactants,intermediates,transition states,and product geometries of the two-and fourfold potential energy surfaces in the reaction system were performed,and potential energy surface maps were plotted.The transition states of the reaction are confirmed by the vibration frequency calculation and the intrinsic reaction coordinate(IRC)analysis.The bonding properties of the species involved in the reaction was discussed by atoms in molecules(AIM)theory and natural bond oribtal(NBO)analysis methods.And 2IM1 and 2IM3 were analyzed by density of states(DOS).In Chapter 4,we studied the reaction mechanism of Actinide Metals U activates C-H bond in ethylene on the surface of One triple and triplet potential energy,all reactants,intermediates,transition states,and product geometries were optimized during the reaction process,and vibration frequencies at each stagnation point were calculated and analyzed at the same theoretical level.Using electron localization function(ELF),atoms in molecules(AIM),and natural bond orbital(NBO)theory different analytical methods were used to study the bonding properties during the reaction and density of states(DOS)analysis of the orbits of each intermediate.