Theoretical Study On The Activation Of Small Molecules By The Transition Metal Zr And Ni~+ In Gas Phase

The essence of the chemical reaction is the breaking of the old bond and the formation of the new bond.It is a long-term goal for researchers to achieve the targeted chemical bond cleavage and synthesis with high selectively.In recent years,the activation of C-C,C-H and C-O bonds by various transition metal atoms(M),ions(M+),oxides(MO)and oxide ions(MO+)in the gas phase draw wide attentions from experimental chemists and theoretical chemists.Experimental research has provides abundant information,such as intrinsic binding properties and thermodynamic data.Theoretical research not only gives a reasonable explanation of the experimental results,but also reveals the nature of the catalytic process mechanism at the molecular level.This provides an important mechanism information and reaction model for people to study similar reactions.In the paper,on the basis of the density functional theory,the two-state reactivity theory in quantum chemistry as well as the experimental results of Lester Andrews,Darrin J.Beller,Carlos Silva López et al.,the Gaussian 09,Crossing 2004,Games and Multiwfn programs are used to study the reaction of the transition metal atoms /ions with small organic molecules in the gas phase.The geometric structures of all reactants,intermediates,transition states and products in the reaction are optimized.The configuration data of the stationary points and the thermodynamic data as well as molecular orbital information are obtained.Finally,the reaction mechanisms and the lowest energy path are identified.This article is divided into five chapters.The first chapter briefly introduces the development of quantum chemistry,research background,and the purpose and content of this study.The second chapter mainly introduces some basic theories and calculation methods of quantum chemistry used in this paper,which provide the theoretical basis for the research of this paper.In the third chapter,the gas phase reaction mechanism of PH3 catalyzed by Zr on singlet and triplet potential energy surfaces(PESs)is studied.The configuration of the stationary points on the reaction potential surface is optimized.The crossing point(CP)and the lowest energy crossing point(MECP)of different spin state potential energy surfaces are determined.The spin-orbit coupling constants(SOC)and the probability of intersystem crossing are calculated.In addition,the bonding properties during the reaction process are studied by three different analytical methods including electronic localization function(ELF),atoms in molecule(AIM)and natural bond orbital(NBO).In the fourth chapter,the reactions of Ni~+ assisted C-C and C-H bond activations of propionaldehyde in the gas phase is studied.The configuration of the stationary points involved in the reaction system is optimized.The reaction mechanisms are determined.The initial complex is analyzed by charge decomposition analysis(CDA).And the evolution of the chemical bond in the reaction is studied using different analytical methods.In the fifth chapter,the reaction of Ni~+-catalyzed ethyl acetate in the gas phase is taken as the object of study.The activation reaction mechanism of C-O bonds in the reaction is analyzed.The initial reaction sites are predicted.All possible reaction paths are identified.The competitive reaction paths are analyzed using the Curtin-Hammett principle,and the minimum energy paths and major products are determined.The evolution of the chemical bond during the reaction is analyzed using different analytical methods.