Issue 29, 2018

Electrophile-promoted Fe-to-N2 hydride migration in highly reduced Fe(N2)(H) complexes

Abstract

One of the emerging challenges associated with developing robust synthetic nitrogen fixation catalysts is the competitive formation of hydride species that can play a role in catalyst deactivation or lead to undesired hydrogen evolution reactivity (HER). It is hence desirable to devise synthetic systems where metal hydrides can migrate directly to coordinated N2 in reductive N–H bond-forming steps, thereby enabling productive incorporation into desired reduced N2-products. Relevant examples of this type of reactivity in synthetic model systems are limited. In this manuscript we describe the migration of an iron hydride (Fe-H) to Nα of a disilylhydrazido(2-) ligand (Fe[double bond, length as m-dash]NNR2) derived from N2via double-silylation in a preceding step. This is an uncommon reactivity pattern in general; well-characterized examples of hydride/alkyl migrations to metal heteroatom bonds (e.g., (R)M[double bond, length as m-dash]NR′ → M–N(R)R′) are very rare. Mechanistic data establish the Fe-to-Nα hydride migration to be intramolecular. The resulting disilylhydrazido(1-) intermediate can be isolated by trapping with CNtBu, and the disilylhydrazine product can then be liberated upon treatment with an additional acid equivalent, demonstrating the net incorporation of an Fe-H equivalent into an N-fixed product.

Graphical abstract: Electrophile-promoted Fe-to-N2 hydride migration in highly reduced Fe(N2)(H) complexes

Supplementary files

Article information

Article type
Edge Article
Submitted
31 May 2018
Accepted
26 Jun 2018
First published
29 Jun 2018
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2018,9, 6264-6270

Electrophile-promoted Fe-to-N2 hydride migration in highly reduced Fe(N2)(H) complexes

M. M. Deegan and J. C. Peters, Chem. Sci., 2018, 9, 6264 DOI: 10.1039/C8SC02380H

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