Modeling Non-Heme Iron Halogenases: High-Spin Oxoiron(IV)–Halide Complexes That Halogenate C–H Bonds

2016 ◽  
Vol 138 (8) ◽  
pp. 2484-2487 ◽  
Author(s):  
Mayank Puri ◽  
Achintesh N. Biswas ◽  
Ruixi Fan ◽  
Yisong Guo ◽  
Lawrence Que
Keyword(s):  
High Spin ◽  
Heme Iron ◽  
Non Heme Iron ◽  
Halide Complexes

scholarly journals Selective C–H halogenation over hydroxylation by non-heme iron(iv)-oxo

2018 ◽  
Vol 9 (40) ◽  
pp. 7843-7858 ◽  
Author(s):  
Sujoy Rana ◽  
Jyoti Prasad Biswas ◽  
Asmita Sen ◽  
Martin Clémancey ◽  
Geneviève Blondin ◽  
...  
Keyword(s):  
Hydrogen Atom ◽  
Heme Iron ◽  
Hydrogen Atom Abstraction ◽  
Non Heme Iron ◽  
Halide Complexes ◽  
Rebound Phenomenon

Synthetic non-heme iron-oxo and iron-halide complexes promote selective halogenation of the sp3-C–H bonds via hydrogen atom abstraction and halide rebound phenomenon.

scholarly journals Non-heme iron hydroperoxo species in superoxide reductase as a catalyst for oxidation reactions

2014 ◽  
Vol 50 (91) ◽  
pp. 14213-14216 ◽  
Author(s):  
S. Rat ◽  
S. Ménage ◽  
F. Thomas ◽  
V. Nivière
Keyword(s):  
High Spin ◽  
Ferric Iron ◽  
Heme Iron ◽  
Superoxide Reductase ◽  
Oxidation Reactions ◽  
Non Heme Iron

The non-heme high-spin ferric iron hydroperoxo species formed in superoxide reductase can act both as a nucleophile and as an electrophile to catalyze oxidation reactions.

scholarly journals Iron (II/III) Halide Complexes Promote the Interconversion of Nitric Oxide and S-nitrosothiols through Reversible Fe-S Interaction

2021 ◽  
Author(s):  
Anna Poptic ◽  
Shiyu Zhang
Keyword(s):  
Nitric Oxide ◽  
Bond Formation ◽  
Spectroscopic Studies ◽  
Heme Iron ◽  
Chloride Complexes ◽  
Physiological Processes ◽  
Non Heme Iron ◽  
Halide Complexes ◽  
Labile Iron

Heme and non-heme iron in biology mediate the storage/release of NO<sup>•</sup> from <i>S</i>-nitrosothiols as a means to control the biological concentration of NO<sup>•</sup>. Despite their importance in many physiological processes, the mechanisms of N-S bond formation/cleavage at Fe centers have been controversial. Herein, we report the interconversion of NO<sup>•</sup> and <i>S</i>-nitrosothiols mediated by Fe<sup>II</sup>/Fe<sup>III</sup> chloride complexes. The reaction of two equivalents of <i>S</i>-nitrosothiol (Ph<sub>3</sub>CSNO) with [Cl<sub>6</sub>Fe<sup>II</sup><sub>2</sub>]<sup>2</sup><sup>-</sup> results in facile release of NO<sup>•</sup> and formation of iron(III) halothiolate. Detailed spectroscopic studies, including in situ UV-vis, IR, and Mössbauer spectroscopy, support the interaction of the S−atom with the Fe<sup>II</sup> center. This is in contrast to the proposed mechanism of NO<sup>•</sup> release from the well-studied “red product” <i>k</i><sup>1</sup>-N bound <i>S</i>-nitrosothiol Fe<sup>II</sup> complex, [(CN)<sub>5</sub>Fe(<i>k</i><sup>1</sup>-N-RSNO)]<sup>3</sup><sup>-</sup>. Additionally, Fe<sup>III</sup> chloride can mediate NO<sup>•</sup> storage through the formation of <i>S</i>-nitrosothiols. Treatment of iron(III) halothiolate with two equivalents of NO<sup>•</sup> regenerates Ph<sub>3</sub>CSNO with the Fe<sup>II</sup> source trapped as the <i>S</i> = 3/2 {FeNO}<sup>7</sup> species [Cl<sub>3</sub>FeNO]<sup>-</sup>, which is inert towards further coordination and activation of <i>S</i>-nitrosothiols. Our work demonstrates how labile iron can mediate the interconversion of NO<sup>•</sup>/thiolate and <i>S</i>-nitrosothiol, which has important implications for how Nature manages the biological concentration of free NO<sup>•</sup>.

scholarly journals Structure and Reactivity of a High-Spin, Non-Heme Iron(III)-Superoxo Complex Supported by Phosphinimide Ligands

2021 ◽  
Author(s):  
Charles Winslow ◽  
Heui Beom Lee ◽  
Mackenzie J. Field ◽  
Simon J Teat ◽  
Jonathan Rittle
Keyword(s):  
Single Crystals ◽  
High Spin ◽  
Heme Iron ◽  
Computational Studies ◽  
Oxidation Processes ◽  
Transient Nature ◽  
Non Heme Iron ◽  
The Stability ◽  
Oxidation Chemistry ◽  
High Spin Iron

Non-heme iron oxygenases utilize dioxygen to accomplish challenging chemical oxidations. Further understanding of the Fe-O<sub>2</sub> intermediates implicated in these processes is challenged by their highly transient nature. To that end, we have developed a ligand platform featuring phosphinimide donors intended to stabilize oxidized, high-spin iron complexes. O<sub>2</sub> exposure of single crystals of a three-coordinate Fe(II) complex of this framework allowed for in crystallo trapping of a terminally-bound Fe-O<sub>2</sub> complex suitable for XRD characterization. Spectroscopic and computational studies of this species support a high-spin Fe(III) center antiferromagnetically coupled to a superoxide ligand, similar to that proposed for numerous non-heme iron oxygenases. In addition to the stability of this synthetic Fe-O<sub>2</sub> complex, its ability to engage in a range of stoichiometric and catalytic oxidation processes demonstrates that this iron-phosphinimide system is primed for development in modelling oxidizing bioinorganic intermediates and green oxidation chemistry.

Low‐Spin and High‐Spin Perferryl Intermediates in Non‐Heme Iron Catalyzed Oxidations of Aliphatic C–H Groups

2021 ◽  
Author(s):  
Alexandra M. Zima ◽  
Oleg Y. Lyakin ◽  
Konstantin Petrovich Bryliakov ◽  
Evgenii P. Talsi
Keyword(s):  
High Spin ◽  
Heme Iron ◽  
Non Heme Iron

scholarly journals Structure and Reactivity of a High-Spin, Non-Heme Iron(III)-Superoxo Complex Supported by Phosphinimide Ligands

2021 ◽  
Author(s):  
Charles Winslow ◽  
Heui Beom Lee ◽  
Mackenzie J. Field ◽  
Simon J Teat ◽  
Jonathan Rittle
Keyword(s):  
Single Crystals ◽  
High Spin ◽  
Heme Iron ◽  
Computational Studies ◽  
Oxidation Processes ◽  
Transient Nature ◽  
Non Heme Iron ◽  
The Stability ◽  
Oxidation Chemistry ◽  
High Spin Iron

Non-heme iron oxygenases utilize dioxygen to accomplish challenging chemical oxidations. Further understanding of the Fe-O<sub>2</sub> intermediates implicated in these processes is challenged by their highly transient nature. To that end, we have developed a ligand platform featuring phosphinimide donors intended to stabilize oxidized, high-spin iron complexes. O<sub>2</sub> exposure of single crystals of a three-coordinate Fe(II) complex of this framework allowed for in crystallo trapping of a terminally-bound Fe-O<sub>2</sub> complex suitable for XRD characterization. Spectroscopic and computational studies of this species support a high-spin Fe(III) center antiferromagnetically coupled to a superoxide ligand, similar to that proposed for numerous non-heme iron oxygenases. In addition to the stability of this synthetic Fe-O<sub>2</sub> complex, its ability to engage in a range of stoichiometric and catalytic oxidation processes demonstrates that this iron-phosphinimide system is primed for development in modelling oxidizing bioinorganic intermediates and green oxidation chemistry.

scholarly journals Iron (II/III) Halide Complexes Promote the Interconversion of Nitric Oxide and S-nitrosothiols through Reversible Fe-S Interaction

2021 ◽  
Author(s):  
Anna Poptic ◽  
Shiyu Zhang
Keyword(s):  
Nitric Oxide ◽  
Bond Formation ◽  
Spectroscopic Studies ◽  
Heme Iron ◽  
Chloride Complexes ◽  
Physiological Processes ◽  
Non Heme Iron ◽  
Halide Complexes ◽  
Labile Iron

Heme and non-heme iron in biology mediate the storage/release of NO<sup>•</sup> from <i>S</i>-nitrosothiols as a means to control the biological concentration of NO<sup>•</sup>. Despite their importance in many physiological processes, the mechanisms of N-S bond formation/cleavage at Fe centers have been controversial. Herein, we report the interconversion of NO<sup>•</sup> and <i>S</i>-nitrosothiols mediated by Fe<sup>II</sup>/Fe<sup>III</sup> chloride complexes. The reaction of two equivalents of <i>S</i>-nitrosothiol (Ph<sub>3</sub>CSNO) with [Cl<sub>6</sub>Fe<sup>II</sup><sub>2</sub>]<sup>2</sup><sup>-</sup> results in facile release of NO<sup>•</sup> and formation of iron(III) halothiolate. Detailed spectroscopic studies, including in situ UV-vis, IR, and Mössbauer spectroscopy, support the interaction of the S−atom with the Fe<sup>II</sup> center. This is in contrast to the proposed mechanism of NO<sup>•</sup> release from the well-studied “red product” <i>k</i><sup>1</sup>-N bound <i>S</i>-nitrosothiol Fe<sup>II</sup> complex, [(CN)<sub>5</sub>Fe(<i>k</i><sup>1</sup>-N-RSNO)]<sup>3</sup><sup>-</sup>. Additionally, Fe<sup>III</sup> chloride can mediate NO<sup>•</sup> storage through the formation of <i>S</i>-nitrosothiols. Treatment of iron(III) halothiolate with two equivalents of NO<sup>•</sup> regenerates Ph<sub>3</sub>CSNO with the Fe<sup>II</sup> source trapped as the <i>S</i> = 3/2 {FeNO}<sup>7</sup> species [Cl<sub>3</sub>FeNO]<sup>-</sup>, which is inert towards further coordination and activation of <i>S</i>-nitrosothiols. Our work demonstrates how labile iron can mediate the interconversion of NO<sup>•</sup>/thiolate and <i>S</i>-nitrosothiol, which has important implications for how Nature manages the biological concentration of free NO<sup>•</sup>.

Strongly Coupled Redox-Linked Conformational Switching at the Active Site of the Non-Heme Iron-Dependent Dioxygenase, TauD

2019 ◽  
Author(s):  
Christopher John ◽  
Greg M. Swain ◽  
Robert P. Hausinger ◽  
Denis A. Proshlyakov
Keyword(s):  
Active Site ◽  
Structural Model ◽  
Heme Iron ◽  
Chemical Transformations ◽  
Experimental Conditions ◽  
Strongly Coupled ◽  
Non Heme Iron ◽  
Reversible Redox ◽  
Wide Range ◽  
Complex Structural

2-Oxoglutarate (2OG)-dependent dioxygenases catalyze C-H activation while performing a wide range of chemical transformations. In contrast to their heme analogues, non-heme iron centers afford greater structural flexibility with important implications for their diverse catalytic mechanisms. We characterize an <i>in situ</i> structural model of the putative transient ferric intermediate of 2OG:taurine dioxygenase (TauD) by using a combination of spectroelectrochemical and semi-empirical computational methods, demonstrating that the Fe (III/II) transition involves a substantial, fully reversible, redox-linked conformational change at the active site. This rearrangement alters the apparent redox potential of the active site between -127 mV for reduction of the ferric state and 171 mV for oxidation of the ferrous state of the 2OG-Fe-TauD complex. Structural perturbations exhibit limited sensitivity to mediator concentrations and potential pulse duration. Similar changes were observed in the Fe-TauD and taurine-2OG-Fe-TauD complexes, thus attributing the reorganization to the protein moiety rather than the cosubstrates. Redox difference infrared spectra indicate a reorganization of the protein backbone in addition to the involvement of carboxylate and histidine ligands. Quantitative modeling of the transient redox response using two alternative reaction schemes across a variety of experimental conditions strongly supports the proposal for intrinsic protein reorganization as the origin of the experimental observations.

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