The Fe2(NO)2 Diamond Core: A Unique Structural Motif In Non-Heme Iron–NO Chemistry

Hai T. Dong, Amy L. Speelman, Claire E. Kozemchak, Debangsu Sil, Carsten Krebs, Nicolai Lehnert

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14 Scopus citations


Non-heme high-spin (hs) {FeNO}8 complexes have been proposed as important intermediates towards N2O formation in flavodiiron NO reductases (FNORs). Many hs-{FeNO}8 complexes disproportionate by forming dinitrosyl iron complexes (DNICs), but the mechanism of this reaction is not understood. While investigating this process, we isolated a new type of non-heme iron nitrosyl complex that is stabilized by an unexpected spin-state change. Upon reduction of the hs-{FeNO}7 complex, [Fe(TPA)(NO)(OTf)](OTf) (1), the N-O stretching band vanishes, but no sign of DNIC or N2O formation is observed. Instead, the dimer, [Fe2(TPA)2(NO)2](OTf)2 (2) could be isolated and structurally characterized. We propose that 2 is formed from dimerization of the hs-{FeNO}8 intermediate, followed by a spin state change of the iron centers to low-spin (ls), and speculate that 2 models intermediates in hs-{FeNO}8 complexes that precede the disproportionation reaction.

Original languageEnglish (US)
Pages (from-to)17695-17699
Number of pages5
JournalAngewandte Chemie - International Edition
Issue number49
StatePublished - Dec 2 2019

All Science Journal Classification (ASJC) codes

  • Catalysis
  • General Chemistry


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