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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 N₂. Here we show that a nitrogen-fixing Fe-N₂ catalyst can be protonated to form a neutral Fe(NNH₂) hydrazido(2-) intermediate, which, upon further protonation, heterolytically cleaves the N-N bond to release [Fe^IV≡N]⁺ and NH₃. These observations provide direct evidence for the viability of a Chatt-type (distal) mechanism for Fe-mediated N₂-to-NH₃ 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.

SUBMITTER: Thompson NB

PROVIDER: S-EPMC6021180 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature

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Nitrogen Fixation via a Terminal Fe(IV) Nitride.

Thompson Niklas B NB Green Michael T MT Peters Jonas C JC

Journal of the American Chemical Society 20171019 43

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 N2. Here we show that a nitrogen-fixing Fe-N2 catalyst can be protonated to form a neutral Fe(NNH2) hydrazido(2-) intermediate, which, upon further protonation, heterolytically cleaves the N-N bond to r ...[more]

PMID: 28992418

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