NMR Reveals That a Highly Reactive Nonheme FeIV=O Complex Retains Its Six-Coordinate Geometry and S=1 State in Solution

Saikat Banerjee, Waqas Rasheed, Ruixi Fan, Apparao Draksharapu, Williamson N. Oloo, Yisong Guo, Larry Que

Research output: Contribution to journalArticle

4 Scopus citations


The [FeIV(O)(Me3NTB)]2+ (Me3NTB=tris[(1-methyl-benzimidazol-2-yl)methyl]amine) complex 1 has been shown by Mössbauer spectroscopy to have an S=1 ground state at 4 K, but is proposed to become an S=2 trigonal-bipyramidal species at higher temperatures based on a DFT model to rationalize its very high C−H bond-cleavage reactivity. In this work, 1H NMR spectroscopy was used to determine that 1 does not have C3-symmetry in solution and is not an S=2 species. Our results show that 1 is unique among nonheme FeIV=O complexes in retaining its S=1 spin state and high reactivity at 193 K, providing evidence that S=1 FeIV=O complexes can be as reactive as their S=2 counterparts. This result emphasizes the need to identify factors besides the ground spin state of the FeIV=O center to rationalize nonheme oxoiron(IV) reactivity.

Original languageEnglish (US)
Pages (from-to)9608-9613
Number of pages6
JournalChemistry - A European Journal
Issue number41
StatePublished - Jul 22 2019


  • DFT calculations
  • NMR spectroscopy
  • nonheme iron
  • oxoiron(IV) complexes
  • two-state reactivity

PubMed: MeSH publication types

  • Journal Article

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