Experimental Definition of the <i>S</i> = 1 π vs <i>S</i> = 2 σ Reactivity and <i>S</i> = 2 Character in the Ground State of an <i>S</i> = 1 Fe<sup>IV</sup>O Complex
Iron(IV)-oxo intermediates found in iron enzymes and artificial catalysts are competent for H atom abstraction in catalytic cycles. For <i>S</i> = 2 intermediates, both axial and equatorial approaches are well-established. The mechanism for <i>S</i> = 1 sites is not as well understood: an equatorial approach is more energetically favorable, and an axial approach requires crossing from the <i>S</i> = 1 to the <i>S</i> = 2 surface. In this study, we use 1s2p resonant inelastic X-ray scattering (RIXS) and Fe L-edge X-ray absorption spectroscopy on the <i>S</i> = 1 [Fe<sup>IV</sup>O(TMC)(CH<sub>3</sub>CN)]<sup>2+</sup> and observe both <i>S</i> = 2 and <i>S</i> = 1 final states, which enables the experimental evaluation of the energetics of the axial and equatorial reactivity of an <i>S</i> = 1 Fe<sup>IV</sup>O center on its <i>S</i> = 2 vs <i>S</i> = 1 surface. The observation of <i>S</i> = 2 final states in the RIXS spectrum demonstrates significant <i>S</i> = 2 character spin-orbit mixed into the <i>S</i> = 1 ground state.
Authors
- Leland Bruce Gee (ORCID: https://orcid.org/0000-0002-5817-3997)
- Michael W. Mara (ORCID: https://orcid.org/0000-0003-3766-9368)
- Dennis Nordlund (ORCID: https://orcid.org/0000-0001-9524-6908)
- Edward I. Solomon (ORCID: https://orcid.org/0000-0003-0291-3199)
- Max D. J. Waters (ORCID: https://orcid.org/0000-0002-3505-627X)
- Thomas Kröll (ORCID: https://orcid.org/0000-0003-2176-6905)
- Ang Zhou (ORCID: https://orcid.org/0000-0003-1450-9169)
- Augustin Braun (ORCID: https://orcid.org/0000-0002-9487-5769)
- Dimosthenis Sokaras (ORCID: https://orcid.org/0000-0001-8117-1933)
- Keith O. Hodgson
- LAWRENCE JUN. QUE (ORCID: https://orcid.org/0000-0002-0989-2813)
- Michael L. Baker (ORCID: https://orcid.org/0000-0002-8246-3177)
- Britt Hedman
Institutions
- University of Minnesota (US)
- University of Minnesota System (US)
- SLAC National Accelerator Laboratory (US)
- Stanford Synchrotron Radiation Lightsource (US)
- Stanford University (US)
Publication Details
- Journal
- Journal of the American Chemical Society
- Published
- 2024-12-13
- DOI
- https://doi.org/10.1021/jacs.4c11034
- Citations
- 4
- Primary Topic
- Metal-Catalyzed Oxygenation Mechanisms
- Type
- article
- Field-Weighted Citation Impact
- 0.63
Funders
- National Science Foundation
- U.S. Department of Energy
- Royal Society of Chemistry
- Human Frontier Science Program
- Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
- National Institutes of Health
- Office of Science
- Stanford Research Computing Center, Stanford University
- National Institute of General Medical Sciences
- Basic Energy Sciences
- Biological and Environmental Research
- SLAC National Accelerator Laboratory