| Noncovalent interactions play a critical role in molecular recognition, crystal engineering, and biological systems, especially in supramolecular chemistry, as molecular assemblies are usually held together through weak interactions. Interest in new types of intermolecular interactions, such as σ-hole and π-hole interactions has recently grown. The applications of halogen bonding in molecular recognition, crystal engineering, and biological systems are affected mainly by the strength of halogen bond. One of the most important and interesting issues on halogen bond is how to strengthen it. The previous studies on the cooperativity have demonstrated the halogen bonds can display cooperative effect with other types of intermolecular interactions.In this work,We mainly research the Group V σ-hole Interaction by the Method of quantum chemistry calculation, analysising the property of the σ-hole Interaction, the halogen bond and the weak Noncovalent interactions. The geometries and the frequencies of the monomers and the complexes, were performed with the Gaussian 03 and Gaussian 09 program package. The molecular electrostatic potentials and topological properties were computered by WFA and AIMALL software,The density difference of molecular formation and Vn were analyzed using Multiwfn software, The main researches are as follows:1. In this work, NCF···O=PX3···(NCF)n(X=F,Cl,Br,H,CH3);n=0,1,2) complexes were constructed and studied based on the second-order M?ller-Plesset perturbation theory(MP2) calculations and the density difference of molecular formation(MFDD) analys1 is, to investigate the enhancing effects of group V σ-hole interactions on the F···O halogen bond. With the number of n increases, the F···O halogen bond becomes stronger, indicating that the group V σ-hole interactions could enhance the F···O halogen bond. With the capacity of donating electrons of X becomes greater and greater, the most negative electrostatic potentials outside the oxygen atom of O=PX3···(NCX)n(n = 0, 1, 2) becomes more and more negative, resulting in stronger F···O halogen bond. In the formation of F···O halogen bond, along the sequence of X = F, Cl, Br, H, CH3 of the negative sites O=PX3, the electric field of lone pair of oxygen becomes greater and causes more decrease of electron density outside the fluorine atom. On the other hand, with n increases from 0 to 2, the group V σ-hole interactions also make electric field of lone pair of oxygen become greater and results in more decrease of electron density outside the fluorine atom.2. The Group V σ-hole interactions, which could be formed between the Phosphorus derivatives and X-CN(X=F, Cl, Br), have attracted more and more attention. In this work, MP2/aug-cc-p VDZ calculations have been carried out for studying the P···N Group V σ-hole interaction in the bimolecular complexes O=PH3···NCX, and the termolecular complexes NCY···O=PH3···NCX and O=PH3···NCX···NCY(X, Y = F, Cl, Br) were designed to investigate the enhancing effects of Y···O and X···N halogen bonds on the Group V σ-hole interaction.(1) When the capacity of donating electrons of Y becomes greater, the VS, max values outside the σ-hole region of O=PH3 becomes increasingly positive with the addition of Y···O halogen bond in NCY···O=PH3, the VS, min values outside the nitrogen atom of NCX becomes increasingly negative with the addition of X···N halogen bond in NCX···NCY, which result in a stronger Group V σ-hole interaction in the NCY···O=PH3···NCX and O=PH3···NCX···NCY(X, Y = F, Cl, Br) termolecular complexes.(2) The P···N Group V σ-hole interaction belongs to the characteristics of closed-shell and a non-covalent interaction, the electrostatic contribution is dominant to the total interaction energy.(3) The larger of the P···N interaction energy, the more polarizable of the P···N interaction. Both the Y···O halogen bonds and X···N halogen bonds strengthen the polarization extent for P···N interaction in the NCY···O=PH3···NCX and O=PH3···NCX···NCY complexes. The Y···O halogen bonds affect the σ-hole region(decreased density region) outside the phosphorus atom more than the P···N internuclear region(increased density region outside the nitrogen atom), while it is contrary for the X···N halogen bonds.3. the pseudo π-hole interactions, which could be formed between the Cyclopropane and the Cyclopropane derivatives M3H6(M=C,Si,Ge) and F-CN, have attracted more and more attention. In this work, MP2/aug-cc-p VTZ calculations have been carried out for studying the pseudo π-hole interaction in the bimolecular complexes M3H6···NCF(M=C,Si,Ge), and the termolecular complexes M3H6···(NCF)2 and tetramolecular complexes M3H6···(NCF)3 were designed to investigate the enhancing effects of the F···N halogen bonds on the pseudo π-hole interaction. the pseudo π-hole interaction belongs to the characteristics of closed-shell and a non-covalent interaction, the electrostatic contribution is dominant to the total interaction energy. with NCF increases from 1 to 3, the VS, min values outside the nitrogen atom of NCF becomes increasingly negative with the addition of F···N halogen bond in(NCF)n(n=1,2,3), the electric field of lone pair of nitrogen becomes greater and causes more decrease of electron density outside the pseudo π-hole region and more increase of electron density outside the nitrogen atom, resulting in stronger the pseudo π-hole interaction.The innovations in this thesis:1. NCF···O=PX3···(NCF)n(X=F,Cl,Br,H,CH3;n=0,1,2) complexes were constructed based on the density difference of molecular formation(MFDD) analys1 is, to investigate the enhancing effects of group V σ-hole interactions on the F···O halogen bond.The electric field of lone pair of oxygen become greater and results in more decrease of electron density outside the fluorine atom.2. the P···N Group V σ-hole interaction in the bimolecular complexes O=PH3···NCX, and the termolecular complexes NCY···O=PH3···NCX and O=PH3···NCX···NCY(X, Y = F, Cl, Br) were constructed by the nuclei centered quantity(Vn) based on the Molecular electrostatic potentials, the greater of the P···N interaction energy, the larger of the quantity ΔΔVn, the more polarizable of the P···N interaction.3. the pseudo π-hole is found in the Cyclopropane and the Cyclopropane derivatives M3H6(M=C,Si,Ge), and we make the more polarizable of the pseudo π-hole interaction to enhance the pseudo π-hole interaction. |
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