Theoretical Studies Of The Interations Between CFCs And Some Atmospheric Gas Molecules

The intermolecular interactions of CFCs with some atmospheric gas molecules binary systems were investigated with Ab initio methods. According to the calculation results of all these complexes, we have taken the systematically analysis about the principle and mechanism at MP₂/aug-cc-pVDZ and MP₂/aug-cc-pVTZ levels.First, ab initio calculations were carried out for system of CFCs (CFC-11, CFC-12, CFC-13) with CO₂, and twelve stable configurations were obtained with no imaginary frequencies. The geometric structures, interaction energy, charge transfer and bond characteristics of the mentioned complexes were calculated. The results of theoretical calculation indicate that there is the weak interaction and that the presence of C–Cl···O and C–F···O bonds in these complexes. The complex of three non-covalent bindings is the most stable according to interaction energies.Then, ten stable complexes of CFCl3 with SO₂ were carried out. According to geometry optimization, frequency, interaction energy, second-order perturbation natural bond orbital and the atoms in molecules theory (AIM) analyses, the Cl···O, F···O, Cl···S and F···S interactions are the main form in these complexes. The NBO analysis has revealed that the n(Cl)→σ*(S–O) interactions give the strongest stabilization to these complexes, furthermore, Cl···O and Cl···S non-covalent bonds are the major interaction forces in these complexes. Similarly, we have been performed on binary supramolecular systems of CF₂Cl₂ with NO and SO₂. It has analyzed the stability of twelve complexes through configuration and interaction energy, natural bond orbital (NBO) analyzes charge transfer and change of dipole for these complexes. The atoms in molecules theory has been used to analyze the nature of the interaction. The results indicate that Cl···N and Cl···O interactions occupy bigger proportion for CF₂Cl₂-NO system, and Cl···O, Cl···S and F···S interactions occupy bigger proportion for CF2Cl2-SO₂ system, and also it is main form of three non-covalent bindings in these complexes. The interactions seem to be very significant as a driving force influencing the arrangement of molecules, especially CF2Cl2-SO₂ system.Based on the above observations, there is the interaction between these atmospheric gas molecules with the mentioned of CFCs, which provide some valuable information and data for studying the environment problem and correlated aspects of chemistry.