Solvation and kinetic isotope effects in H and D abstraction reactions from formate ions by D, H, and Mu atoms in aqueous solutions.
Electron paramagnetic resonance free induction decay attenuation and muon spin rotation measurements were performed in the temperature range of liquid water for the reactions of the hydrogen isotopes D, H, and Mu with undeuterated and deuterated formate ions. Accurate rate constants were determined, and excellent Arrhenius behavior represented bywas found in all cases. Ab initio calculations at the MP2 and the QCISD level with the aug-cc-pvDZ basis set reveal that the reaction has no electronic barrier in the gas phase. This contrasts with quite sizeable activation energies observed in aqueous solution, and it suggests that the barrier is entirely solvent induced. Calculations at the above mentioned ab initio level using a polarized dielectric continuum for the solvated reaction system restore a realistic barrier and confirm this interpretation. It is shown that the solvent effect is a consequence of a pronounced change of polarization of the system along the reaction path. It may be more appropriate to describe the reaction as a consecutive electron-proton transfer rather than an H atom abstraction.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 943247
- Report Number(s):
- ANL/CHM/JA-38603; TRN: US200916%%681
- Journal Information:
- Phys. Chem. Chem. Phys., Vol. 3, Issue 11 ; 2001; ISSN 1463-9076
- Country of Publication:
- United States
- Language:
- ENGLISH
Similar Records
Rate constants for the thermal decomposition of ethanol and its bimolecular reactions with OH and D : reflected shock tube and theoretical studies.
Dual-level reaction-path dynamics (the III approach to VTST with semiclassical tunneling). Application to OH + NH[sub 3] [yields] H[sub 2]O + NH[sub 2]