Jump to main content
Jump to site search

Issue 47, 2014
Previous Article Next Article

Excited state potential energy surfaces and their interactions in FeIV<img border='0' src='http://www.rsc.org/images/entities/h2_char_e001.gif' alt='[double bond, length as m-dash]'/>O active sites

Author affiliations

Abstract

The non-heme ferryl active sites are of significant interest for their application in biomedical and green catalysis. These sites have been shown to have an S = 1 or S = 2 ground spin state; the latter is functional in biology. Low-temperature magnetic circular dichroism (LT MCD) spectroscopy probes the nature of the excited states in these species including ligand-field (LF) states that are otherwise difficult to study by other spectroscopies. In particular, the temperature dependences of MCD features enable their unambiguous assignment and thus determination of the low-lying excited states in two prototypical S = 1 and S = 2 NHFeIV[double bond, length as m-dash]O complexes. Furthermore, some MCD bands exhibit vibronic structures that allow mapping of excited-state interactions and their effects on the potential energy surfaces (PESs). For the S = 2 species, there is also an unusual spectral feature in both near-infrared absorption and MCD spectra – Fano antiresonance (dip in Abs) and Fano resonance (sharp peak in MCD) that indicates the weak spin–orbit coupling of an S = 1 state with the S = 2 LF state. These experimental data are correlated with quantum-chemical calculations that are further extended to analyze the low-lying electronic states and the evolution of their multiconfigurational characters along the Fe–O PESs. These investigations show that the lowest-energy states develop oxyl FeIII character at distances that are relevant to the transition state (TS) for H-atom abstraction and define the frontier molecular orbitals that participate in the reactivity of S = 1 vs. S = 2 non-heme FeIV[double bond, length as m-dash]O active sites. The S = 1 species has only one available channel that requires the C–H bond of a substrate to approach perpendicular to the Fe–oxo bond (the π channel). In contrast, there are three channels (one σ and two π) available for the S = 2 non-heme FeIV[double bond, length as m-dash]O system allowing C–H substrate approach both along and perpendicular to the Fe–oxo bond that have important implications for enzymatic selectivity.

Graphical abstract: Excited state potential energy surfaces and their interactions in FeIV<img border='0' src='http://www.rsc.org/images/entities/char_e001.gif' alt='[double bond, length as m-dash]'/>O active sites

Back to tab navigation

Publication details

The article was received on 07 May 2014, accepted on 03 Jun 2014 and first published on 04 Jun 2014


Article type: Perspective
DOI: 10.1039/C4DT01366B
Citation: Dalton Trans., 2014,43, 17567-17577
  • Open access: Creative Commons BY license
  •   Request permissions

    Excited state potential energy surfaces and their interactions in FeIV<img border='0' src='http://www.rsc.org/images/entities/h2_char_e001.gif' alt='[double bond, length as m-dash]'/>O active sites

    M. Srnec, S. D. Wong and E. I. Solomon, Dalton Trans., 2014, 43, 17567
    DOI: 10.1039/C4DT01366B

    This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. Material from this article can be used in other publications provided that the correct acknowledgement is given with the reproduced material.

    Reproduced material should be attributed as follows:

    • For reproduction of material from NJC:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the Centre National de la Recherche Scientifique (CNRS) and the RSC.
    • For reproduction of material from PCCP:
      [Original citation] - Published by the PCCP Owner Societies.
    • For reproduction of material from PPS:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the European Society for Photobiology, the European Photochemistry Association, and RSC.
    • For reproduction of material from all other RSC journals:
      [Original citation] - Published by The Royal Society of Chemistry.

    Information about reproducing material from RSC articles with different licences is available on our Permission Requests page.

Search articles by author

Spotlight

Advertisements