The Theoretical Study Of Some New Type Of Weak Interaction

Noncovalent interactions play a critical role in a wide range of chemical and biological processes,such as molecular recognition,conformation transformation,and molecular packing in crystal engineering.The intermolecular interactions have been recognized as starting from conventional hydrogen bonds.In recent years,some novel intermolecular interactions such as halogen bonds,?-hole interactions,especially the ?-hole interactions and pseudo ?-hole interactions have attracted more and more attention.However,little attention has been paid to the formation of halogen bonds containing metal atoms.In particular,there are no reports on the ?-hole interactions containing the new inorganic heterocyclic molecules.Therefore,we have carried out further research on these areas.The geometries,frequencies and intermolecular interaction energies of all the complexes were calculated by using the Gaussian 09 program packages.The WFA-SAS program was used to compute the electrostatic potential of the surface of the monomer molecules.The QTAIM theory and AIMALL program were used to analyze the topological properties of the electron density at the saddle point.The NBO 6.0 program was used to analyze the natural bond orbital,and the difference of molecular formation density was calculated by Multiwfn program.This paper is divided into the two following parts:1.The platinum complexes of trans-PtX₂?NH₃?₂…ClF?X = OH,F,Cl,Br?and cis-PtX₂?NH₃?₂…ClF?X = OH,F,Cl,Br?were constructed and the optimized with the method of MP2 with the aug-cc-pvDZ basis sets.Based on the analysis of the electrostatic potential of the monomer complexes,the interaction energy,the density difference of the complexes and the QTAIM analysis,a negative electrostatic potential region on the platinum monomer complex was found,indicating that it could act as the halogen bond acceptor,and the intensity of the interaction of the dimer complexes depends on the nature and configuration of the platinum ligands,which are somewhat more stable than the trans-complexes,and the weak interactions are stronger than hydrogen bond.It was found that it has some covalent bond characteristics by the QTAIM analysis.The analysis of natural bond orbital shows that the amount of charge transfer between molecular orbital is obvious when the dimer complex were formed.In addition,there is a very good linear relationship between the density difference and the two-body interaction energy,demonstrating that the polarization effect plays a key role in the formation of the complex.2.In recent years,inorganic main-group heterocycles have attracted great interest incomputational and synthetic chemistry,as well as in materials science.In this section,according to the positive electrostatic potentials above the surface of heterocyclic compounds S₂N₂,SN₂P₂?Here we named: SN₂P₂-1,SN₂P₂-2 and SN₂P₂-3?,and the negative electrostatic potential outside the X atom of XH₃?X=N,P,As?,the S₂N₂/SN₂P₂···XH₃?X=N,P,As?complexes were constructed and optimized at the MP2/aug-cc-pVTZ level.The X atom of XH₃?X=N,P,As?is almost perpendicular to the ring of heterocyclic compounds.The ?-hole interaction energy becomes greater as the trend of S₂N₂,SN₂P₂-1,SN₂P₂-2,SN₂P₂-3.QTAIM shows that the ?-hole interactions are weak and belong to “closed-shell” noncovalent interactions,and the exchange energy contributes the most according to the energy decomposition analysis?EDA?.The polarization effect also plays an important role in the formation of ?-hole complexes with the phenomenon that the decrease of electronic density in the ?-hole region and the increase of electric density outside the X atom of XH₃?X=N,P,As?.The innovation of this paper:1.For the first time,it has been found and studied that in the platinum-platinum complex,there is a negative electrostatic potential region above the platinum atom.Platinum can be used as an acceptor of the halogen bond and form the halogen bond.The intensity of the interaction depends on the nature of the platinum ligand and structure.The charge transfer between PtX₂?NH₃?₂ molecule and ClF molecule-related molecular orbital is also very large,and the interaction force is stronger than the hydrogen bonding and has some covalent characteristics.The stronger the interaction force of Pt?II?… Cl,the more the contribution of polarizing energy and dispersion energy to the total interaction energy.The more the electron density on the outside of Pt atom decreases,the more the charge density increases between Pt atom and Cl atom.This indicates that the polarization effect plays a very important role in the formation of the Pt?II?… Cl interaction system.2.There are positive electrostatic potential regions in the inorganic heterocyclic S₂N₂,SN₂P₂ and its isomers: ?-hole,through which the interaction with XH₃?X = N,P,As?molecules forms ?-hole.This type of ?-hole interaction and hydrogen bonds are similar,all belong to the shell non-covalent interaction.The results of energy decomposition and molecular generation density difference show that in this kind of ?-hole interaction,the dispersion energy can be the main component.In addition,the polarization is also negligible,in the formation of ?-hole interaction,the electronic rearrangement...