Exploring secondary-sphere interactions in Fe–N_xH_y complexes relevant to N_2 fixation
- Creators
- Creutz, Sidney E.
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Peters, Jonas C.
Abstract
Hydrogen bonding and other types of secondary-sphere interactions are ubiquitous in metalloenzyme active sites and are critical to the transformations they mediate. Exploiting secondary sphere interactions in synthetic catalysts to study the role(s) they might play in biological systems, and to develop increasingly efficient catalysts, is an important challenge. Whereas model studies in this broad context are increasingly abundant, as yet there has been relatively little progress in the area of synthetic catalysts for nitrogen fixation that incorporate secondary sphere design elements. Herein we present our first study of Fe–NxHy complexes supported by new tris(phosphine)silyl ligands, abbreviated as [SiP^(Nme_3)] and [SiP^(iPr_2)P^(Nme)], that incorporate remote tertiary amine hydrogen-bond acceptors within a tertiary phosphine/amine 6-membered ring. These remote amine sites facilitate hydrogen-bonding interactions via a boat conformation of the 6-membered ring when certain nitrogenous substrates (e.g., NH_3 and N_2H_4) are coordinated to the apical site of a trigonal bipyramidal iron complex, and adopt a chair conformation when no H-bonding is possible (e.g., N_2). Countercation binding at the cyclic amine is also observed for anionic {Fe–N_2}− complexes. Reactivity studies in the presence of proton/electron sources show that the incorporated amine functionality leads to rapid generation of catalytically inactive Fe–H species, thereby substantiating a hydride termination pathway that we have previously proposed deactivates catalysts of the type [EP^R_3]FeN_2 (E = Si, C).
Additional Information
© 2016 The Royal Society of Chemistry. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. Received 31st October 2016; Accepted 7th December 2016; First published online 08 Dec 2016. This work was supported by the NIH (GM 070757) and the Gordon and Betty Moore Foundation. Larry Henling and Mike Takase are thanked for crystallographic assistance.Attached Files
Published - c6sc04805f.pdf
Supplemental Material - c6sc04805f1.pdf
Supplemental Material - c6sc04805f2.cif
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Additional details
- Alternative title
- Exploring secondary-sphere interactions in Fe–NxHy complexes relevant to N2 fixation
- PMCID
- PMC5363375
- Eprint ID
- 73060
- Resolver ID
- CaltechAUTHORS:20161221-100943169
- NIH
- GM 070757
- Gordon and Betty Moore Foundation
- Created
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2016-12-21Created from EPrint's datestamp field
- Updated
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2022-04-06Created from EPrint's last_modified field