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Fe–N_2/CO complexes that model a possible role for the interstitial C atom of FeMo-cofactor (FeMoco)

Rittle, Jonathan and Peters, Jonas C. (2013) Fe–N_2/CO complexes that model a possible role for the interstitial C atom of FeMo-cofactor (FeMoco). Proceedings of the National Academy of Sciences of the United States of America, 110 (40). pp. 15898-15903. ISSN 0027-8424. PMCID PMC3791750. doi:10.1073/pnas.1310153110. https://resolver.caltech.edu/CaltechAUTHORS:20131024-101957270

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Abstract

We report here a series of four- and five-coordinate Fe model complexes that feature an axial tri(silyl)methyl ligand positioned trans to a substrate-binding site. This arrangement is used to crudely model a single-belt Fe site of the FeMo-cofactor that might bind N_2 at a position trans to the interstitial C atom. Reduction of a trigonal pyramidal Fe(I) complex leads to uptake of N_2 and subsequent functionalization furnishes an open-shell Fe–diazenido complex. A related series of five-coordinate Fe–CO complexes stable across three redox states is also described. Spectroscopic, crystallographic, and Density Functional Theory (DFT) studies of these complexes suggest that a decrease in the covalency of the Fe–C_alkyl interaction occurs upon reduction and substrate binding. This leads to unusually long Fe–C_alkyl bond distances that reflect an ionic Fe–C bond. The data presented are contextualized in support of a hypothesis wherein modulation of a belt Fe–C interaction in the FeMo-cofactor facilitates substrate binding and reduction.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1073/pnas.1310153110 DOIArticle
http://www.pnas.org/cgi/doi/10.1073/pnas.1310153110PublisherArticle
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3791750/PubMed CentralArticle
ORCID:
AuthorORCID
Peters, Jonas C.0000-0002-6610-4414
Additional Information:© 2013 National Academy of Sciences. Edited by Douglas C. Rees, Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA, and approved August 6, 2013 (received for review May 29, 2013). We thank Larry Henling and Charlene Tsay for crystallographic assistance as well as Dr. Angelo di Bilio for assistance with EPR measurements. This work was supported by the National Institutes of Health (GM 070757) and the Gordon and Betty Moore Foundation. J.R. was supported by a National Science Foundation graduate fellowship. Author contributions: J.R. and J.C.P. designed research; J.R. performed research; J.R. and J.C.P. analyzed data; and J.R. and J.C.P. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission. Data deposition: The atomic coordinates have been deposited in the Cambridge Structural Database, Cambridge Crystallographic Data Centre, Cambridge CB2 1EZ, United Kingdom (CSD reference nos. 909104–909108, 941163, and 941164).
Funders:
Funding AgencyGrant Number
NIHGM 070757
Gordon and Betty Moore FoundationUNSPECIFIED
NSF Graduate Research FellowshipUNSPECIFIED
Subject Keywords:nitrogenase; nitrogen fixation; Fe-N-2 complexes; small molecule activation; ammonia production
Issue or Number:40
PubMed Central ID:PMC3791750
DOI:10.1073/pnas.1310153110
Record Number:CaltechAUTHORS:20131024-101957270
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20131024-101957270
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:42045
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:24 Oct 2013 17:43
Last Modified:10 Nov 2021 04:37

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