Nitrogen Fixation via a Terminal Fe(IV) Nitride
Abstract
Terminal iron nitrides (Fe≡N) have been proposed as intermediates of (bio)catalytic nitrogen fixation, yet experimental evidence to support this hypothesis has been lacking. In particular, no prior synthetic examples of terminal Fe≡N species have been derived from N_2. Here we show that a nitrogen-fixing Fe–N_2 catalyst can be protonated to form a neutral Fe(NNH_2) hydrazido(2−) intermediate, which, upon further protonation, heterolytically cleaves the N–N bond to release [Fe^(IV)≡N]^+ and NH_3. These observations provide direct evidence for the viability of a Chatt-type (distal) mechanism for Fe-mediated N_2-to-NH_3 conversion. The physical oxidation state range of the Fe complexes in this transformation is buffered by covalency with the ligand, a feature of possible relevance to catalyst design in synthetic and natural systems that facilitate multiproton/multielectron redox processes.
Additional Information
© 2017 American Chemical Society. Received: September 1, 2017; Published: October 9, 2017. We thank M. Latimer, E. Nelson, C. Krest, C. Miller, and K. Mittra for assistance with synchrotron measurements. This work was supported by the Resnick Sustainability Institute at Caltech (Graduate Fellowship, N.B.T.), as well as the NIH (GM 070757). Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. Additional notes in the Supporting Information. The authors declare no competing financial interest.Attached Files
Accepted Version - nihms-975149.pdf
Supplemental Material - ja7b09364_si_001.cif
Supplemental Material - ja7b09364_si_002.pdf
Supplemental Material - ja7b09364_si_003.pdf
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Additional details
- PMCID
- PMC6021180
- Eprint ID
- 82248
- Resolver ID
- CaltechAUTHORS:20171010-095936880
- Resnick Sustainability Institute
- GM-070757
- NIH
- DE-AC02-76SF00515
- Department of Energy (DOE)
- Created
-
2017-10-10Created from EPrint's datestamp field
- Updated
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2022-03-22Created from EPrint's last_modified field
- Caltech groups
- Resnick Sustainability Institute