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 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 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.

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

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

The stability of dislocation networks under various oxygen-doping conditions in superconducting Bi2Sr2CaCu2Oy single crystals and their influence on the flux pinning properties

1994 ◽  
Vol 52 ◽  
pp. 802-803
Author(s):  
Y. Feng ◽  
X. Y. Cai ◽  
R. J. Kelley ◽  
D. C. Larbalestier
Keyword(s):  
Single Crystals ◽  
Oxygen Content ◽  
Basal Plane ◽  
Flux Pinning ◽  
Pinning Centers ◽  
Before And After ◽  
Anomalous Peak ◽  
Basal Plane Dislocation ◽  
The Stability ◽  
Further Development

The issue of strong flux pinning is crucial to the further development of high critical current density Bi-Sr-Ca-Cu-O (BSCCO) superconductors in conductor-like applications, yet the pinning mechanisms are still much debated. Anomalous peaks in the M-H (magnetization vs. magnetic field) loops are commonly observed in Bi2Sr2CaCu2Oy (Bi-2212) single crystals. Oxygen vacancies may be effective flux pinning centers in BSCCO, as has been found in YBCO. However, it has also been proposed that basal-plane dislocation networks also act as effective pinning centers. Yang et al. proposed that the characteristic scale of the basal-plane dislocation networksmay strongly depend on oxygen content and the anomalous peak in the M-H loop at ˜20-30K may be due tothe flux pinning of decoupled two-dimensional pancake vortices by the dislocation networks. In light of this, we have performed an insitu observation on the dislocation networks precisely at the same region before and after annealing in air, vacuumand oxygen, in order to verify whether the dislocation networks change with varying oxygen content Inall cases, we have not found any noticeable changes in dislocation structure, regardless of the drastic changes in Tc and the anomalous magnetization. Therefore, it does not appear that the anomalous peak in the M-H loops is controlled by the basal-plane dislocation networks.

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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