The hydrogen-bonded complexes formed from interaction of trihalomethanes CHX₃ (X = F, Cl, Br) with nitrosyl hydride HNO were studied using ab initio MO calculations at the second-order perturbation theory (MP2/6-311++G(d,p)). Each interaction contains at least five separate equilibrium structures. Calculated binding energies range from 4 to 8 kJ mol^-1 with both ZPE and BSSE corrections. While CHBr₃ leads to the most stable complexes with HNO, CHF₃ forms the least stable counterparts. The strength of complexes thus tends to increase from F to Cl to Br, which is consistent with a decrease of deprotonation enthalpy of the corresponding C-H bonds. It is remarkable that all the C-H and N-H bonds are shortened upon complexation, giving rise to an increase of their stretching frequencies. A blue shift is thus observed for the N-H bonds of the type N-H⋯X (X = F, Cl, Br); such a contraction of the covalent N-H bond is extremely rare. © the Owner Societies.

Trung N.T., Hue T.T., Nguyen M.T.

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Từ khóa : carbon; hydrogen; nitrogen; nitrogen oxide; trihalomethane; article; chemistry; electron; hydrogen bond; infrared radiation; quantum theory; vibration; Carbon; Electrons; Hydrogen; Hydrogen Bonding; Infrared Rays; Nitrogen; Nitrogen Oxides; Quantum Theory; Trihalomethanes; Vibration