A Theoretical Study Of Intermolecular Interactions In Metal-π Complexes

Intermolecular interactions in metallo-organic compounds play important roles in organic chemistry,biological chemistry,soft matter,supramolecular chemistry and so on.Understanding the orgin of this kind of interactions is a hot topic in theoretical chemistry.Among the interactions in metallo-organic compounds,metal-7t interactions have been received widespread attentions.Because of the complexity in metal-πcompounds,the nature of their interactions is still unclear.It is the motivation of the thesis.In chapter 3,the nature of metal cation-π interaction is explored.The valence bond energy decomposition analysis scheme(VB-EDA)proposed by our group recently is used to study a series of metal cationic complexes(metal cations=Li+,Na’,K+,Mgt+,Ca2+;π=ethylene and benzene).A new covalency index,which is proposed based on the VB-EDA results,is used to study the covalent characters of the cation-π interactions.It is shown that only the C2H4-Mg2+ complex can be considered as a covalent bond complex,while other complexes are typical ionic complexes.It is found that a large portion of non-electrostatic interaction in total interaction enrgy does not always indicate a covalent bond.In chapter 4,the physical origin of the interactions in metal-biphenyl complexes is studied.AIM,NBO,and genelized Kohn-Sham energy decomposition anlysis(GKS-EDA),which was developed by our group,are empolyed to analyze M/Mn+-C12H10(M=Li.Na,Mg,Sc,Ti;Mn+=Li+,Na+,Mg2+,Sc+,Ti2+).It is concluded that:1.π back donor plays an important role in the formation of clamshell geometry,M/Mn+-C12H10(M=Mg,Sc,Ti;Mn+=Sc+,Tie2+);2.There is metal-ligand interaction in the clamshell complexes,and there is σ donor and-π back donor effect in the interactions.