TY - JOUR

T1 - Evolution of vibrational bands upon gradual protonation/deprotonation of arsinic acid H2As(O)OH in media of different polarity

AU - Тупикина, Елена Юрьевна

AU - Коростелев, Владислав Олегович

AU - Крутин, Данил Вячеславович

AU - Толстой, Петр Михайлович

PY - 2023/1/20

Y1 - 2023/1/20

N2 - This computational work is devoted to the investigation (MP2/def2-TZVP) of the geometry and IR parameters of arsinic acid H2AsOOH and its hydrogen-bonded complexes under vacuum and in media with different polarity. The medium effects were accounted for in two ways: (1) implicitly, using the IEFPCM model, varying the dielectric permittivity (ϵ) and (2) explicitly, by considering hydrogen-bonded complexes of H2As(O)OH with various hydrogen bond donors (41 complexes) or acceptors (38 complexes), imitating a gradual transition to the As(OH)2+ or AsO2− moiety, respectively. It was shown that the transition from vacuum to a medium with ϵ > 1 causes the As(O)OH fragment to lose its flatness. The solvent polar medium introduces significant changes in the geometry and IR spectral parameters of hydrogen-bonded complexes too: as the polarity of a medium increases, weak hydrogen bonds become weaker, and strong and medium hydrogen bonds become stronger; in the case of a complex with two hydrogen bonds cooperativity effects are observed. In almost all cases the driving force of these changes appears to be preferential solvation of charge-separated structures. In the limiting case of complete deprotonation (or conversely complete protonation) the vibrational frequencies of νAs = O and νAs-O turn into νAs-O(asym) and νAs-O(sym), respectively. In the intermediate cases the distance between νAs O and νAs-O is sensitive to both implicit solvation and explicit solvation and the systematic changes of this distance can be used for estimation of the degree of proton transfer within the hydrogen bond.

AB - This computational work is devoted to the investigation (MP2/def2-TZVP) of the geometry and IR parameters of arsinic acid H2AsOOH and its hydrogen-bonded complexes under vacuum and in media with different polarity. The medium effects were accounted for in two ways: (1) implicitly, using the IEFPCM model, varying the dielectric permittivity (ϵ) and (2) explicitly, by considering hydrogen-bonded complexes of H2As(O)OH with various hydrogen bond donors (41 complexes) or acceptors (38 complexes), imitating a gradual transition to the As(OH)2+ or AsO2− moiety, respectively. It was shown that the transition from vacuum to a medium with ϵ > 1 causes the As(O)OH fragment to lose its flatness. The solvent polar medium introduces significant changes in the geometry and IR spectral parameters of hydrogen-bonded complexes too: as the polarity of a medium increases, weak hydrogen bonds become weaker, and strong and medium hydrogen bonds become stronger; in the case of a complex with two hydrogen bonds cooperativity effects are observed. In almost all cases the driving force of these changes appears to be preferential solvation of charge-separated structures. In the limiting case of complete deprotonation (or conversely complete protonation) the vibrational frequencies of νAs = O and νAs-O turn into νAs-O(asym) and νAs-O(sym), respectively. In the intermediate cases the distance between νAs O and νAs-O is sensitive to both implicit solvation and explicit solvation and the systematic changes of this distance can be used for estimation of the degree of proton transfer within the hydrogen bond.

UR - https://www.mendeley.com/catalogue/1069336d-aeee-3785-b231-e5659c725389/

U2 - 10.1039/D2CP06060D

DO - 10.1039/D2CP06060D

M3 - Article

VL - 25

SP - 8664

EP - 8675

JO - Physical Chemistry Chemical Physics

JF - Physical Chemistry Chemical Physics

SN - 1463-9076

IS - 12

ER -