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OH-Stretching Overtone Induced Dynamics in HSO3F from Reactive Molecular Dynamics Simulations
Sebastian Brickel1, Markus Meuwly1
1Department of Chemistry, University of Basel , Klingelbergstrasse 80, 4056 Basel, Switzerland.
The Journal of Physical Chemistry. A
|June 16, 2017
Summary
Dynamics in fluorosulfonic acid (HSO3F) show H-transfer upon OH-stretch excitation. HF-elimination is rare, indicating a dynamically closed channel, unlike related compounds.
Area of Science:
- Chemical Dynamics
- Theoretical Chemistry
- Molecular Spectroscopy
Background:
- Understanding molecular dynamics is crucial for predicting chemical reactions.
- Vibrational excitation can induce dissociation in molecules like H2SO4 and HSO3Cl.
- Fluorosulfonic acid (HSO3F) presents a unique case for studying dissociation pathways.
Purpose of the Study:
- To characterize OH-stretch induced dynamics in fluorosulfonic acid (HSO3F).
- To investigate the mechanisms of H-transfer and HF-elimination.
- To compare dynamics with related molecules and theoretical models.
Main Methods:
- Multisurface adiabatic reactive molecular dynamics (MS-ARMD) simulations.
- Parametrization of the global reactive potential energy surface at the MP2/6-311G++(2p,2d) level.
- Analysis of a statistically significant number of trajectories.
Main Results:
- OH-stretch excitation primarily leads to H-transfer dynamics.
- HF-elimination is observed in only 1 out of 5000 trajectories, requiring high excitation (ν ≥ 6).
- This contrasts with facile H2O and HCl elimination in H2SO4 and HSO3Cl, respectively.
Conclusions:
- The HF-production channel in HSO3F is dynamically closed, not statistically limited.
- Dynamical effects, rather than RRKM theory predictions, govern HF elimination.
- Findings align with experimental observations of non-RRKM behavior in hydrofluoroethanes.
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