Dioxygen Activation at Mononuclear Nonheme Iron Active Sites:  Enzymes, Models, and Intermediates

2004 ◽  
Vol 104 (2) ◽  
pp. 939-986 ◽  
Author(s):  
Miquel Costas ◽  
Mark P. Mehn ◽  
Michael P. Jensen ◽  
Lawrence Que
Keyword(s):  
Active Sites ◽  
Nonheme Iron ◽  
Dioxygen Activation ◽  
Iron Active Sites

Dioxygen Activation at Mononuclear Nonheme Iron Active Sites: Enzymes, Models, and Intermediates

ChemInform ◽  
2004 ◽  
Vol 35 (21) ◽  
Author(s):  
Miquel Costas ◽  
Mark P. Mehn ◽  
Michael P. Jensen ◽  
Lawrence Jr. Que
Keyword(s):  
Active Sites ◽  
Nonheme Iron ◽  
Dioxygen Activation ◽  
Iron Active Sites

Dioxygen Activation by Enzymes with Mononuclear Non-Heme Iron Active Sites

1996 ◽  
Vol 96 (7) ◽  
pp. 2607-2624 ◽  
Author(s):  
Lawrence Que ◽  
Raymond Y. N. Ho
Keyword(s):  
Active Sites ◽  
Heme Iron ◽  
Dioxygen Activation ◽  
Non Heme Iron ◽  
Iron Active Sites

A Pyridinic Fe-N4 Macrocycle Effectively Models the Active Sites in Fe/N-Doped Carbon Electrocatalysts

2020 ◽  
Author(s):  
Travis Marshall-Roth ◽  
Nicole J. Libretto ◽  
Alexandra T. Wrobel ◽  
Kevin Anderton ◽  
Nathan D. Ricke ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Active Sites ◽  
Catalytic Properties ◽  
Reduction Reaction ◽  
Iron Phthalocyanine ◽  
Electrochemical Studies ◽  
Onset Potential ◽  
Nitrogen Doped Carbon ◽  
Iron Active Sites

Iron- and nitrogen-doped carbon (Fe-N-C) materials are leading candidates to replace platinum in fuel cells, but their active site structures are poorly understood. A leading postulate is that iron active sites in this class of materials exist in an Fe-N<sub>4</sub> pyridinic ligation environment. Yet, molecular Fe-based catalysts for the oxygen reduction reaction (ORR) generally feature pyrrolic coordination and pyridinic Fe-N<sub>4</sub> catalysts are, to the best of our knowledge, non-existent. We report the synthesis and characterization of a molecular pyridinic hexaazacyclophane macrocycle, (phen<sub>2</sub>N<sub>2</sub>)Fe, and compare its spectroscopic, electrochemical, and catalytic properties for oxygen reduction to a prototypical Fe-N-C material, as well as iron phthalocyanine, (Pc)Fe, and iron octaethylporphyrin, (OEP)Fe, prototypical pyrrolic iron macrocycles. N 1s XPS signatures for coordinated N atoms in (phen<sub>2</sub>N<sub>2</sub>)Fe are positively shifted relative to (Pc)Fe and (OEP)Fe, and overlay with those of Fe-N-C. Likewise, spectroscopic XAS signatures of (phen<sub>2</sub>N<sub>2</sub>)Fe are distinct from those of both (Pc)Fe and (OEP)Fe, and are remarkably similar to those of Fe-N-C with compressed Fe–N bond lengths of 1.97 Å in (phen<sub>2</sub>N<sub>2</sub>)Fe that are close to the average 1.94 Å length in Fe-N-C. Electrochemical studies establish that both (Pc)Fe and (phen<sub>2</sub>N<sub>2</sub>)Fe have relatively high Fe(III/II) potentials at ~0.6 V, ~300 mV positive of (OEP)Fe. The ORR onset potential is found to directly correlate with the Fe(III/II) potential leading to a ~300 mV positive shift in the onset of ORR for (Pc)Fe and (phen<sub>2</sub>N<sub>2</sub>)Fe relative to (OEP)Fe. Consequently, the ORR onset for (phen<sub>2</sub>N<sub>2</sub>)Fe and (Pc)Fe is within 150 mV of Fe-N-C. Unlike (OEP)Fe and (Pc)Fe, (phen<sub>2</sub>N<sub>2</sub>)Fe displays excellent selectivity for 4-electron ORR with <4% maximum H<sub>2</sub>O<sub>2</sub> production, comparable to Fe-N-C materials. The aggregate spectroscopic and electrochemical data establish (phen<sub>2</sub>N<sub>2</sub>)Fe as a pyridinic iron macrocycle that effectively models Fe-N-C active sites, thereby providing a rich molecular platform for understanding this important class of catalytic materials.<p><b></b></p>

The Selective Oxidation of Hydrocarbons on Isolated Iron Active Sites under Ambient Conditions

2019 ◽  
Vol 41 (6) ◽  
pp. 946-946
Author(s):  
Zhengliang Qi Zhengliang Qi ◽  
Junmei Liu Junmei Liu ◽  
Wanwan Guo and Jun Huang Wanwan Guo and Jun Huang
Keyword(s):  
Ionic Liquid ◽  
Activated Carbon ◽  
Carbon Material ◽  
Active Sites ◽  
High Selectivity ◽  
Good Activity ◽  
Ambient Conditions ◽  
Oxidation Of Hydrocarbons ◽  
Fe Catalysts ◽  
Iron Active Sites

The N-doped carbon material supported Fe catalysts were developed for the oxidation of C-H bond of hydrocarbons to ketones and alcohols. The supported Fe catalysts were prepared by pyrolysis of [CMIM]3Fe(CN)6 ionic liquid in activated carbon. And the Fe(Ⅲ)@CN-600 showed good activity and high selectivity for the oxidation of alfa C-H bond of alkylbenzenes. The isolated Fe(Ⅲ) iron active sites should be responsible for the high activity and selectivity for the oxidation of hydrocarbons to ketones. Several ketones were obtained in good to excellent yields. Moreover, cyclohexanone can also be obtained through the oxidation of cyclohexane.

scholarly journals Proton- and Reductant-Assisted Dioxygen Activation by a Nonheme Iron(II) Complex to Form an Oxoiron(IV) Intermediate

2008 ◽  
Vol 47 (37) ◽  
pp. 7064-7067 ◽  
Author(s):  
Aurore Thibon ◽  
Jason England ◽  
Marlène Martinho ◽  
Victor G. Young ◽  
Jonathan R. Frisch ◽  
...  
Keyword(s):  
Nonheme Iron ◽  
Dioxygen Activation

Theoretical Study on Methane Oxidation Catalyzed by Fe/ZSM-5: The Significant Role of Water on Binuclear Iron Active Sites

2016 ◽  
Vol 120 (48) ◽  
pp. 27422-27429 ◽  
Author(s):  
Miao He ◽  
Jie Zhang ◽  
Xiu-Liang Sun ◽  
Biao-Hua Chen ◽  
Yang-Gang Wang
Keyword(s):  
Methane Oxidation ◽  
Significant Role ◽  
Active Sites ◽  
Theoretical Study ◽  
Iron Active Sites ◽  
Binuclear Iron
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