Characterization of an Fe≡N-NH2 Intermediate Relevant to Catalytic N2 Reduction to NH3

John S. Anderson, George E. Cutsail, Jonathan Rittle, Bridget A. Connor, William A. Gunderson, Limei Zhang, Brian M. Hoffman, Jonas C. Peters

Research output: Contribution to journalArticle

70 Citations (Scopus)

Abstract

The ability of certain transition metals to mediate the reduction of N2 to NH3 has attracted broad interest in the biological and inorganic chemistry communities. Early transition metals such as Mo and W readily bind N2 and mediate its protonation at one or more N atoms to furnish M(NxHy) species that can be characterized and, in turn, extrude NH3. By contrast, the direct protonation of Fe-N2 species to Fe(NxHy) products that can be characterized has been elusive. Herein, we show that addition of acid at low temperature to [(TPB)Fe(N2)][Na(12-crown-4)] results in a new S = 1/2 Fe species. EPR, ENDOR, Mössbauer, and EXAFS analysis, coupled with a DFT study, unequivocally assign this new species as [(TPB)Fe≡N-NH2]+, a doubly protonated hydrazido(2-) complex featuring an Fe-to-N triple bond. This unstable species offers strong evidence that the first steps in Fe-mediated nitrogen reduction by [(TPB)Fe(N2)][Na(12-crown-4)] can proceed along a distal or "Chatt-type" pathway. A brief discussion of whether subsequent catalytic steps may involve early or late stage cleavage of the N-N bond, as would be found in limiting distal or alternating mechanisms, respectively, is also provided. (Chemical Equation Presented).

Original languageEnglish (US)
Pages (from-to)7803-7809
Number of pages7
JournalJournal of the American Chemical Society
Volume137
Issue number24
DOIs
StatePublished - Jun 24 2015

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Protonation
Transition metals
Bioinorganic Chemistry
Metals
Electron Spin Resonance Spectroscopy
Discrete Fourier transforms
Paramagnetic resonance
Nitrogen
Atoms
Temperature
Acids
12-crown-4
Inorganic Chemistry

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Anderson, J. S., Cutsail, G. E., Rittle, J., Connor, B. A., Gunderson, W. A., Zhang, L., ... Peters, J. C. (2015). Characterization of an Fe≡N-NH2 Intermediate Relevant to Catalytic N2 Reduction to NH3. Journal of the American Chemical Society, 137(24), 7803-7809. https://doi.org/10.1021/jacs.5b03432

Characterization of an Fe≡N-NH2 Intermediate Relevant to Catalytic N2 Reduction to NH3. / Anderson, John S.; Cutsail, George E.; Rittle, Jonathan; Connor, Bridget A.; Gunderson, William A.; Zhang, Limei; Hoffman, Brian M.; Peters, Jonas C.

In: Journal of the American Chemical Society, Vol. 137, No. 24, 24.06.2015, p. 7803-7809.

Research output: Contribution to journalArticle

Anderson, JS, Cutsail, GE, Rittle, J, Connor, BA, Gunderson, WA, Zhang, L, Hoffman, BM & Peters, JC 2015, 'Characterization of an Fe≡N-NH2 Intermediate Relevant to Catalytic N2 Reduction to NH3', Journal of the American Chemical Society, vol. 137, no. 24, pp. 7803-7809. https://doi.org/10.1021/jacs.5b03432
Anderson, John S. ; Cutsail, George E. ; Rittle, Jonathan ; Connor, Bridget A. ; Gunderson, William A. ; Zhang, Limei ; Hoffman, Brian M. ; Peters, Jonas C. / Characterization of an Fe≡N-NH2 Intermediate Relevant to Catalytic N2 Reduction to NH3. In: Journal of the American Chemical Society. 2015 ; Vol. 137, No. 24. pp. 7803-7809.
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