Theoretical Investigation On The Intermolecular Interactions In Halogen, Chalcogen And Nitrogen Complexes

Abstract:Although the research on the intermolecular interaction has been developed by leaps and bounds in recent years, there is still a blank in the investigation on hydrogen bond and haogen bond in the dimer and trimer between different molecules, and the study on the cooperativity of halogen bond and hydrogen bond is not deep enough, too. Consequently, the theoretical investigations on geometric configuration, interaction energy and the cooperativity in hydrogen bonds or between hydrogen bond and halogen bond in halogen, chalcogen and nitrogen complexes have been carried out with the second order perturbation theory (MP2) method in this paper. The natures of the intermolecular interaction are discussed through the electrostatic analysis and "atoms in molecules"(AIM) analysis. The conclusions in this paper can not only enrich the theoretical knowledge of halogen bond and hydrogen bond, but can promot the experiment researches and applications in related fields of them. The concrete research contents are as follows:1. The theoretical computations are carried out on the intermolecular interactions between (HCl/HBr)n and BrX (X=F, Cl, Br; n=1,2) with aug-cc-pVDZ basis set. The following conclusions are obtained. There are four types of interactions between HC1and BrX which are hydrogen bond, halogen bond, unusual hydrogen bond and unusual halogen bond, respectively. The interaction energies of usual bonds increase with the increase of the electronegativity of X atoms. The interaction energies of unusual bonds decline with the increase of the electronegativity of X atoms. These characteristics can be explained by the electrostatic distribution on the surface of HCl/HBr and BrX molecules. The computational conclusions of geometric structures and interaction energies of the trimers show that the stability of molecular structure depends on the type of trimer's structure, the relative strength of the hydrogen bond and hydrogen bond, and the number of the unusual bonds. The values of the cooperative energies and the synergetic contributions all demonstrate that the cooperativity plays an important role in the formation process of these three-body compounds. The absolute values of cooperative contribution are in the range of0.80%to21.59%. The conclusions of AIM analysis indicate that the electrostatic (closed-shell) interactions occupy a dominant position in these compounds.2. The theoretical investigations are carried out on the HX--(BrCl)n (X=F, Cl, Br; n=1;2) system with aug-cc-pVTZ basis set. The results of the structural parameters, interaction energies and electrostatic potentials on the molecular surfaces of HX and BrCl suggest that HBr can form the strongest halogen bond acting as donor of halogen bond, while HF can form the strongest hydrogen bond acting as donor of hydrogen bond. The research results of the trimers showed that the stronger the electronegativity of halogen atom is, the more stable the trimer is. The factors of affecting the stability of different configurations are the strength of the halogen and hydrogen bond and the mode of intermolecular interactions between HX and two BrCl. The absolute values of cooperative contributions in trimers are in the range of0.86%?15.31%. The AIM analysis demonstrates that these intermolecule interactions are electrostatic interaction in essential.3. The theoretical computations have been carried out for the monomers, dimers (HX-H2Y) and trimers (H2Y…HX…H2Y, H2Y…HX…H2Y) between HX and H2Y with aug-cc-pVTZ basis. According to the calculation results, the stability of the compound has direct contact with the electronegativity of X and Y atom. The stronger the electronegativity of negatively charged atom is, the greater the stability of the corresponding compound is. The positive cooperativities are found between the different hydrogen bonds in all three-body complexes. Cooperative contributions are in the range of14.59-21.26%, indicating that the cooperativites in these complexes are highly significant. The conclusions of AIM analysis demonstrate most of the intermolecular interactions are typical closed-shell interactions. However, the H…O bonds in H2O…HF…H2O, H2O…HBr…H2O and HF…H2O…HF are stabilized by local charge concentration which is between the closed-shell and opened-shell interactions.4. Theoretical investigation about the influences of F/Cl substitution on the geometries, energies and cooperativites of intermolecular interactions between HX and H2Y are investigated with aug-cc-pVTZ basis set. The conclusions demonstrate that the structural parameters and stabilities of all complexes are directly related to the electronegativity of X atom. The favorable cooperativities are observed in diffeent intermolecular interaction of three-body complexes. The cooperative contributions of HX…FY…HX and HX…HClY…HX exist in the ranges of18.19?23.45%and11.27?22.03%respectively, while the cooperative contributions of HFY…FX…HFY and HCl1Y…HX…HClY are in the ranges of12.87?20.17%and12.09?21.33%. AIM analyses indicate that these compounds are closed-shell interactions.5. Aiming at the environmental issues on which world focus in recent years-the climate warming, the chlorine anion (Cl-), guanidine salt cations ((NH2)3C+) and CO2gas molecule system is selected on which the quantum chemical calculation and molecular dynamics simulation has been carried, providing theoretical foundations for designing and developing new guanidinium ionic liquids with high absorption performance. The structure characteristics of guanidinium ionic liquids and the mechanism of guanidinium ionic liquids capturing CO2molecular are discussed. The strong interactions are found between guanidine cation and chlorine anion, whose interaction energy is about100kcal/mol. The function model is given priority to Middle model. The CO2gases dissolve in the gaps of guanidinium ionic liquid, which doesn't obviously influence the structure of the ion pairs. There are35figures,37tables and252references.