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Title: Non-heme High-Spin {FeNO} 6–8 Complexes: One Ligand Platform Can Do It All

Abstract

Heme and non-heme iron-nitrosyl complexes are important intermediates in biology. While there are numerous examples of low-spin heme iron-nitrosyl complexes in different oxidation states, much less is known about high-spin (hs) non-heme iron-nitrosyls in oxidation states other than the formally ferrous NO adducts ({FeNO} 7 in the Enemark-Feltham notation). In this study, we present a complete series of hs-{Fe-NO} 6-8 complexes using the TMG 3tren coligand. Redox transformations from the hs-{FeNO} 7 complex [Fe(TMG 3tren)(NO)] 2+ to its {FeNO} 6 and {FeNO} 8 analogs do not alter the coordination environment of the iron center, allowing for detailed comparisons between these species. Here, we present new MCD, NRVS, XANES/EXAFS and Mössbauer data, demonstrating that these redox transformations are metal based, which allows us to access hs-Fe(II)-NO¯, Fe(III)-NO¯ and Fe(IV)-NO¯ complexes. Vibrational data, analyzed by NCA, directly quantify changes in Fe-NO bonding along this series. Optical data allow for the identification of a “spectator” charge-transfer transition that, together with Mössbauer and XAS data, directly monitors electronic changes of the Fe center. Using EXAFS, we are also now able to provide structural data for all complexes. The magnetic properties of the complexes are further analyzed (from magnetic Mössbauer). The properties of our hs-{FeNO}more » 6-8 complexes are then contrasted to corresponding, low-spin iron-nitrosyl complexes, where redox transformations are generally NO-centered. The hs-{FeNO} 8 complex can further be protonated by weak acids, and the product of this reaction is characterized. Altogether, these results provide unprecedented insight into the properties of biologically relevant non-heme iron-nitrosyl complexes in three relevant oxidation states.« less

Authors:
 [1];  [1];  [2];  [3];  [3];  [3]; ORCiD logo [2];  [1]; ORCiD logo [1]
  1. Univ. of Michigan, Ann Arbor, MI (United States)
  2. The Pennsylvania State Univ., University Park, PA (United States)
  3. Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1489682
Grant/Contract Number:  
AC02-06CH11357
Resource Type:
Accepted Manuscript
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 140; Journal Issue: 36; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Speelman, Amy L., White, Corey J., Zhang, Bo, Alp, E. Ercan, Zhao, Jiyong, Hu, Michael, Krebs, Carsten, Penner-Hahn, James, and Lehnert, Nicolai. Non-heme High-Spin {FeNO}6–8 Complexes: One Ligand Platform Can Do It All. United States: N. p., 2018. Web. doi:10.1021/jacs.8b06095.
Speelman, Amy L., White, Corey J., Zhang, Bo, Alp, E. Ercan, Zhao, Jiyong, Hu, Michael, Krebs, Carsten, Penner-Hahn, James, & Lehnert, Nicolai. Non-heme High-Spin {FeNO}6–8 Complexes: One Ligand Platform Can Do It All. United States. doi:10.1021/jacs.8b06095.
Speelman, Amy L., White, Corey J., Zhang, Bo, Alp, E. Ercan, Zhao, Jiyong, Hu, Michael, Krebs, Carsten, Penner-Hahn, James, and Lehnert, Nicolai. Tue . "Non-heme High-Spin {FeNO}6–8 Complexes: One Ligand Platform Can Do It All". United States. doi:10.1021/jacs.8b06095. https://www.osti.gov/servlets/purl/1489682.
@article{osti_1489682,
title = {Non-heme High-Spin {FeNO}6–8 Complexes: One Ligand Platform Can Do It All},
author = {Speelman, Amy L. and White, Corey J. and Zhang, Bo and Alp, E. Ercan and Zhao, Jiyong and Hu, Michael and Krebs, Carsten and Penner-Hahn, James and Lehnert, Nicolai},
abstractNote = {Heme and non-heme iron-nitrosyl complexes are important intermediates in biology. While there are numerous examples of low-spin heme iron-nitrosyl complexes in different oxidation states, much less is known about high-spin (hs) non-heme iron-nitrosyls in oxidation states other than the formally ferrous NO adducts ({FeNO}7 in the Enemark-Feltham notation). In this study, we present a complete series of hs-{Fe-NO}6-8 complexes using the TMG3tren coligand. Redox transformations from the hs-{FeNO}7 complex [Fe(TMG3tren)(NO)]2+ to its {FeNO}6 and {FeNO}8 analogs do not alter the coordination environment of the iron center, allowing for detailed comparisons between these species. Here, we present new MCD, NRVS, XANES/EXAFS and Mössbauer data, demonstrating that these redox transformations are metal based, which allows us to access hs-Fe(II)-NO¯, Fe(III)-NO¯ and Fe(IV)-NO¯ complexes. Vibrational data, analyzed by NCA, directly quantify changes in Fe-NO bonding along this series. Optical data allow for the identification of a “spectator” charge-transfer transition that, together with Mössbauer and XAS data, directly monitors electronic changes of the Fe center. Using EXAFS, we are also now able to provide structural data for all complexes. The magnetic properties of the complexes are further analyzed (from magnetic Mössbauer). The properties of our hs-{FeNO}6-8 complexes are then contrasted to corresponding, low-spin iron-nitrosyl complexes, where redox transformations are generally NO-centered. The hs-{FeNO}8 complex can further be protonated by weak acids, and the product of this reaction is characterized. Altogether, these results provide unprecedented insight into the properties of biologically relevant non-heme iron-nitrosyl complexes in three relevant oxidation states.},
doi = {10.1021/jacs.8b06095},
journal = {Journal of the American Chemical Society},
number = 36,
volume = 140,
place = {United States},
year = {2018},
month = {8}
}

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