ic4031156_si_002.xyz (64.54 kB)
A Dissociative Quantum Mechanical/Molecular Mechanical Molecular Dynamics Simulation and Infrared Experiments Reveal Characteristics of the Strongly Hydrolytic Arsenic(III)
dataset
posted on 2014-11-17, 00:00 authored by Lorenz
R. Canaval, Oliver M. D. Lutz, Alexander K. H. Weiss, Christian W. Huck, Thomas S. HoferThis
work presents a hybrid ab initio quantum mechanical/molecular mechanical
simulation at the RI-MP2 level of theory investigating the hydrolysis
process of arsenic(III), ultimately leading to arsenous acid (H3AsO3). A newly implemented dissociative water model
has been applied to treat the interactions in the classical region,
which is capable of describing non-neutral water species such as hydroxide
and oxonium ions. Three stages of hydrolysis have been observed during
the simulation and besides profound dynamical considerations, detailed
insights into structural changes and atomic partial charge shifts
are presented. In particular, the geometrical properties of H-bonds
involved in each of the three proton transfer events and subsequent
proton hopping reactions are discussed. A Laguerre tessellation analysis
has been employed to estimate the molecular volume of H3AsO3. Estimations of pKa values
of the arsenic(III)-aquo-complexes have been obtained at the G4 and
CBS-Q//B3 levels of theory using a thermodynamic cycle, whereas rate
constants for the final hydrolysis step have been determined via reaction
path optimization and transition state theory. Newly recorded Fourier
transform infrared (FT-IR) spectroscopy measurements have been compared
to power spectra obtained from the simulation data, confirming its
quality. The simulation findings, as well as results from computational
spectroscopic calculations utilizing the PT2-VSCF methodology, proved
valuable for the interpretation of the experimental FT-IR data, elucidating
the particularities of the strongly observed IR Raman noncoincidence
effect.
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Infrared Experiments Reveal Characteristicsproton transfer eventsrate constantsspectroscopy measurementsLaguerre tessellation analysisMechanicalsimulation findingsPTpower spectrareaction path optimizationH 3AsOhydrolysis stepIR Raman noncoincidence effectoxonium ionscharge shiftsarsenicsimulation datadissociative water modeltransition state theoryhydrolysis processspectroscopic calculationsarsenous acidab initio quantumpKa valuesH 3AsO EstimationsG 4
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