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Nghiên cứu vai trò của các tương tác trong việc làm bền các phức giữa CO2 với C2H3X (X = H, F, Cl, Br)

Nguyễn Tiến Trung, Phạm Ngọc Khánh, Ngô Thị Thanh Phương, Nguyễn Lê Tuấn, Phạm Vũ Nhật, Trần Thành Huế, Nguyễn Thị Thu Trang

Abstract


The interactions of ethylene and its monohalogen–substituted derivatives with CO2 were investigated. Interaction energies of 16 stable complexes obtained range from -1.13 to -5.57 kJ.mol-1 at the CCSD(T)/aug-cc-pVDZ//MP2/aug-cc-pVDZ level. The stability of the C2H4∙∙∙ CO2 complex is determined by the π∙∙∙π interaction which is due to electron density transfer from MO-π(C=C) to MO‑π*(C=O) dominating the transition from MO-π(C=O) to MO-π*(C=C). Remarkably, contribution of the π∙∙∙π interaction to strength of complex of CO2-philic compounds and CO2 has been revealed for the first time. Substitution of an H atom by a halogen in C2H4 makes CO2∙∙∙C2H3X (X = F, Cl, Br) slightly more stable than CO2∙∙∙C2H4, and all the halogenated derivatives have equivalent stability. The strength of CO2∙∙∙C2H3X which is contributed by Lewis acid-base interaction, attractive electrostatic interaction and hydrogen bond, is different from the case of CO2∙∙∙C2H4. The obtained results also show that, upon complexation, a contraction of C-H bond length involved in hydrogen bond and an increase in its stretching frequency are affected by shape of the complex beside predominant dependence on polarity of C-H bond in isolated monomer.


Keywords


Solubility, carbon dioxide, Lewis acid-base interaction, π∙∙∙π interaction

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