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Title: Identification of the dominant photochemical pathways and mechanistic insights to the ultrafast ligand exchange of Fe(CO)5 to Fe(CO)4EtOH

We utilized femtosecond time-resolved resonant inelastic X-ray scattering and ab initio theory to study the transient electronic structure and the photoinduced molecular dynamics of a model metal carbonyl photocatalyst Fe(CO)5 in ethanol solution. We propose mechanistic explanation for the parallel ultrafast intra-molecular spin crossover and ligation of the Fe(CO)4 which are observed following a charge transfer photoexcitation of Fe(CO)5 as reported in our previous study [Wernet et al., Nature 520, 78 (2015)]. We find that branching of the reaction pathway likely happens in the 1A1 state of Fe(CO)4. A sub-picosecond time constant of the spin crossover from 1B2 to 3B2 is rationalized by the proposed 1B21A13B2 mechanism. Ultrafast ligation of the 1B2 Fe(CO)4 state is significantly faster than the spin-forbidden and diffusion limited ligation process occurring from the 3B2 Fe(CO)4 ground state that has been observed in the previous studies. We propose that the ultrafast ligation occurs via 1B21A11A' Fe(CO)4EtOH pathway and the time scale of the 1A1 Fe(CO)4 state ligation is governed by the solute-solvent collision frequency. In conclusion, our study emphasizes the importance of understanding the interaction of molecular excited states with the surrounding environment to explain the relaxationmore » pathways of photoexcited metal carbonyls in solution.« less
Authors:
 [1] ;  [2] ;  [3] ;  [1] ;  [4] ;  [4] ;  [4] ;  [3] ;  [3] ;  [5] ;  [6] ;  [6] ;  [6] ;  [7] ;  [7] ;  [4] ;  [8] ;  [9] ;  [10] ;  [2] more »;  [4] ;  [1] « less
  1. Helmholtz-Zentrum Berlin (HZB), (Germany). German Research Centre for Materials and Energy; Univ. Potsdam, Potsdam (Germany). Institut fur Physik und Astronomie
  2. Stockholm Univ. (Sweden). Department of Physics
  3. Max Planck Institute for Biophysical Chemistry, Am Fassberg, Gottingen (Germany)
  4. Helmholtz-Zentrum Berlin (HZB), (Germany). German Research Centre for Materials and Energy
  5. SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource (SSRL)
  6. SLAC National Accelerator Lab., Menlo Park, CA (United States). PULSE Institute
  7. SLAC National Accelerator Lab., Menlo Park, CA (United States). Linac Coherent Light Source (LCLS)
  8. MAX-lab, Lund (Sweden)
  9. Utrecht Univ. Utrecht (Netherlands). Department of Chemistry
  10. Max Planck Institute for Biophysical Chemistry, Am Fassberg, Gottingen (Germany); Gottingen Univ. (Germany); Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
Publication Date:
OSTI Identifier:
1242357
Grant/Contract Number:
AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
Structural Dynamics
Additional Journal Information:
Journal Volume: 3; Journal Issue: 4; Journal ID: ISSN 2329-7778
Publisher:
American Crystallographic Association/AIP
Research Org:
SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS