| Autor: |
Antolini C; Department of Chemistry, University of Rhode Island, Kingston, Rhode Island 02881, United States., Jacoby DJ; Department of Chemistry, University of Rhode Island, Kingston, Rhode Island 02881, United States., Tiano SM; Department of Chemistry, University of Rhode Island, Kingston, Rhode Island 02881, United States., Otolski CJ; Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States., Doumy G; Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States., March AM; Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States., Walko DA; Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States., Goodwill JE; Department of Civil and Environmental Engineering, University of Rhode Island, Kingston, Rhode Island 02881, United States., Hayes D; Department of Chemistry, University of Rhode Island, Kingston, Rhode Island 02881, United States. |
| Abstrakt: |
Hypervalent iron intermediates have been invoked in the catalytic cycles of many metalloproteins, and thus, it is crucial to understand how the coupling between such species and their environment can impact their chemical and physical properties in such contexts. In this work, we take advantage of the solvent kinetic isotope effect (SKIE) to gain insight into the nonradiative deactivation of electronic excited states of the aqueous ferrate(VI) ion. We observe an exceptionally large SKIE of 9.7 for the nanosecond-scale relaxation of the lowest energy triplet ligand field state to the ground state. Proton inventory studies demonstrate that a single solvent O-H bond is coupled to the ion during deactivation, likely due to the sparse vibrational structure of ferrate(VI). Such a mechanism is consistent with that reported for the deactivation of f - f excited states of aqueous trivalent lanthanides, which exhibit comparably large SKIE values. This phenomenon is ascribed entirely to dissipation of energy into a higher overtone of a solvent acceptor mode, as any impact on the apparent relaxation rate due to a change in solvent viscosity is negligible. |
