scholarly journals Mechanistic elucidation of C–H oxidation by electron rich non-heme iron(iv)–oxo at room temperature

2015 ◽  
Vol 51 (77) ◽  
pp. 14469-14472 ◽  
Author(s):  
Sujoy Rana ◽  
Aniruddha Dey ◽  
Debabrata Maiti
Keyword(s):  
Hydrogen Atom ◽  
Room Temperature ◽  
Heme Iron ◽  
Hydrogen Atom Abstraction ◽  
Non Heme Iron

Non-heme iron(iv)–oxo species form iron(iii) intermediates during hydrogen atom abstraction (HAA) from the C–H bond.

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 Isolation of a Bimetallic Cobalt(III) Nitride and Examination of its Hydrogen Atom Abstraction Chemistry and Reactivity Towards H2

2020 ◽  
Author(s):  
Debabrata Sengupta ◽  
Christian Sandoval-Pauker ◽  
Emily Schueller ◽  
Angela M. Encerrado-Manriquez ◽  
Alejandro J. Metta-Magaña ◽  
...  
Keyword(s):  
Hydrogen Atom ◽  
Density Functional ◽  
Room Temperature ◽  
Hydrogen Atom Abstraction ◽  
Functional Theory ◽  
Kinetic Rate ◽  
Rate Analysis ◽  
Stable Product ◽  
Activation Pathways ◽  
Computational Analyses

Room temperature photolysis of the bis(azide)cobaltate(II) complex [Na(THF)<sub>x</sub>][(<sup>ket</sup>guan)Co(N3)2] (<sup>ket</sup>guan = [(tBu2CN)C(NDipp)2]–, Dipp = 2,6-diisopropylphenyl) (3a) in THF cleanly forms the binuclear cobalt nitride [Na(THF)4{[(<sup>ket</sup>guan)Co(N3)]2(μ-N)}]<sub>n</sub> (1). Compound 1 represents the first example of an isolable, bimetallic cobalt nitride complex, and it has been fully characterized by spectroscopic, magnetic, and computational analyses. Density functional theory supports a CoIII=N=CoIII canonical form with significant π-bonding between the cobalt centers and the nitride atom. Unlike other Group 9 bridging nitride complexes, no radical character is detected at the bridging N-atom of 1. Indeed, 1 is unreactive towards weak C-H donors and even co-crystallizes with a molecule of cyclohexadiene (CHD) in its crystallographic unit cell to give 1·CHD as a room temperature stable product. Notably, addition of pyridine to 1 or photolyzed solutions of [(<sup>ket</sup>guan)Co(N3)(py)]<sub>2</sub> (4a) leads to destabilization via activation of the nitride unit, resulting in the mixed-valent Co(II)/(III) bridged imido species [(<sup>ket</sup>guan)Co]2(μ-NH)(μ-N3) (5) formed from intermolecular hydrogen atom abstraction (HAA) of strong C-H bonds (BDE ~ 100 kcal/mol). Kinetic rate analysis of the formation of 5 in the presence of C6H12 or C6D12 gives a KIE = 2.5±0.1, supportive of a HAA formation path-way. The reactivity of our system was further probed by photolyzing C6D6/py-d5 solutions of 4a under an H2 atmosphere (150 psi), which leads to the exclusive formation of the bis(imido)[(<sup>ket</sup>guan)Co(μ-NH)]2 (6) as a result of dihydrogen activa-tion. These results provide unique insights into the chemistry and electronic structure of late 3d-metal nitrides while providing entryway into C-H activation pathways.

A non-heme cationic Fe(iii)-complex intercalated in montmorillonite K-10: synthesis, characterization and catalytic alkane hydroxylation with H2O2 at room temperature

2014 ◽  
Vol 4 (9) ◽  
pp. 3180-3185 ◽  
Author(s):  
Anand Pariyar ◽  
Suranjana Bose ◽  
Achintesh Narayan Biswas ◽  
Sudip Barman ◽  
Pinaki Bandyopadhyay
Keyword(s):  
Room Temperature ◽  
Heme Iron ◽  
Environmentally Benign ◽  
Efficient Catalyst ◽  
Non Heme Iron ◽  
Alkane Hydroxylation ◽  
Selective Hydroxylation

An efficient catalyst for highly selective hydroxylation of alkanes with environmentally benign H2O2 at room temperature has been designed by the intercalation of a non-heme iron(iii) complex into smectite montmorillonite K-10.

scholarly journals C(sp3)-H Fluorination with a Copper(II)/(III) Redox Couple

2020 ◽  
Author(s):  
Jamey Bower ◽  
Andrew Cypcar ◽  
Brenda Henriquez ◽  
S. Chantal E. Stieber ◽  
Shiyu Zhang
Keyword(s):  
Hydrogen Atom ◽  
Organic Compounds ◽  
Kinetic Data ◽  
Room Temperature ◽  
Hydrogen Atom Abstraction ◽  
Fluoride Ion ◽  
Halogen Bonds ◽  
Fluoride Complex ◽  
Carbon Radicals ◽  
Halide Complexes

<p>Despite the growing interest in the synthesis of fluorinated organic compounds, few methods are able to incorporate fluoride ion directly into alkyl C-H bonds. Here, we report the C(sp<sup>3</sup>)-H fluorination reactivity of a formally copper(III) fluoride complex. The C-H fluorination intermediate, <b>L</b>CuF, along with its chloride and bromide analogs, <b>L</b>CuCl and <b>L</b>CuBr, were prepared directly from halide sources with a chemical oxidant and fully characterized. While all three copper(III) halide complexes capture carbon radicals efficiently to afford C(sp<sup>3</sup>)-halogen bonds, <b>L</b>CuF is two orders of magnitude more efficient at hydrogen atom abstraction (HAA) than <b>L</b>CuCl and <b>L</b>CuBr. Alongside reported kinetic data for other <b>L</b>Cu(III) species, we established a positive correlation between ligand basicity and the rate of HAA. The capability of <b>L</b>CuF to perform both hydrogen atom abstraction and radical capture was leveraged to enable fluorination of allylic and benzylic C-H bonds and α-C-H bonds of ethers at room temperature.</p>

Energetics of non-heme iron reactivity: can ab initio calculations provide the right answer?

2020 ◽  
Vol 22 (41) ◽  
pp. 23908-23919
Author(s):  
Milica Feldt ◽  
Carlos Martín-Fernández ◽  
Jeremy N. Harvey
Keyword(s):  
Hydrogen Atom ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Computational Methods ◽  
Hydrogen Atom Transfer ◽  
Heme Iron ◽  
Reaction Pathways ◽  
Non Heme Iron ◽  
Epoxidation Reaction ◽  
The Right

We use a variety of computational methods to characterize and compare the hydrogen atom transfer (HAT) and epoxidation reaction pathways for oxidation of cyclohexene by an iron(iv)-oxo complex.

scholarly journals Isolation of a Bimetallic Cobalt(III) Nitride and Examination of its Hydrogen Atom Abstraction Chemistry and Reactivity Towards H2

2020 ◽  
Author(s):  
Debabrata Sengupta ◽  
Christian Sandoval-Pauker ◽  
Emily Schueller ◽  
Angela M. Encerrado-Manriquez ◽  
Alejandro J. Metta-Magaña ◽  
...  
Keyword(s):  
Hydrogen Atom ◽  
Density Functional ◽  
Room Temperature ◽  
Hydrogen Atom Abstraction ◽  
Functional Theory ◽  
Kinetic Rate ◽  
Rate Analysis ◽  
Stable Product ◽  
Activation Pathways ◽  
Computational Analyses

Room temperature photolysis of the bis(azide)cobaltate(II) complex [Na(THF)<sub>x</sub>][(<sup>ket</sup>guan)Co(N3)2] (<sup>ket</sup>guan = [(tBu2CN)C(NDipp)2]–, Dipp = 2,6-diisopropylphenyl) (3a) in THF cleanly forms the binuclear cobalt nitride [Na(THF)4{[(<sup>ket</sup>guan)Co(N3)]2(μ-N)}]<sub>n</sub> (1). Compound 1 represents the first example of an isolable, bimetallic cobalt nitride complex, and it has been fully characterized by spectroscopic, magnetic, and computational analyses. Density functional theory supports a CoIII=N=CoIII canonical form with significant π-bonding between the cobalt centers and the nitride atom. Unlike other Group 9 bridging nitride complexes, no radical character is detected at the bridging N-atom of 1. Indeed, 1 is unreactive towards weak C-H donors and even co-crystallizes with a molecule of cyclohexadiene (CHD) in its crystallographic unit cell to give 1·CHD as a room temperature stable product. Notably, addition of pyridine to 1 or photolyzed solutions of [(<sup>ket</sup>guan)Co(N3)(py)]<sub>2</sub> (4a) leads to destabilization via activation of the nitride unit, resulting in the mixed-valent Co(II)/(III) bridged imido species [(<sup>ket</sup>guan)Co]2(μ-NH)(μ-N3) (5) formed from intermolecular hydrogen atom abstraction (HAA) of strong C-H bonds (BDE ~ 100 kcal/mol). Kinetic rate analysis of the formation of 5 in the presence of C6H12 or C6D12 gives a KIE = 2.5±0.1, supportive of a HAA formation path-way. The reactivity of our system was further probed by photolyzing C6D6/py-d5 solutions of 4a under an H2 atmosphere (150 psi), which leads to the exclusive formation of the bis(imido)[(<sup>ket</sup>guan)Co(μ-NH)]2 (6) as a result of dihydrogen activa-tion. These results provide unique insights into the chemistry and electronic structure of late 3d-metal nitrides while providing entryway into C-H activation pathways.

scholarly journals C(sp3)-H Fluorination with a Copper(II)/(III) Redox Couple

2020 ◽  
Author(s):  
Jamey Bower ◽  
Andrew Cypcar ◽  
Brenda Henriquez ◽  
S. Chantal E. Stieber ◽  
Shiyu Zhang
Keyword(s):  
Hydrogen Atom ◽  
Organic Compounds ◽  
Kinetic Data ◽  
Room Temperature ◽  
Hydrogen Atom Abstraction ◽  
Fluoride Ion ◽  
Halogen Bonds ◽  
Fluoride Complex ◽  
Carbon Radicals ◽  
Halide Complexes

<p>Despite the growing interest in the synthesis of fluorinated organic compounds, few methods are able to incorporate fluoride ion directly into alkyl C-H bonds. Here, we report the C(sp<sup>3</sup>)-H fluorination reactivity of a formally copper(III) fluoride complex. The C-H fluorination intermediate, <b>L</b>CuF, along with its chloride and bromide analogs, <b>L</b>CuCl and <b>L</b>CuBr, were prepared directly from halide sources with a chemical oxidant and fully characterized. While all three copper(III) halide complexes capture carbon radicals efficiently to afford C(sp<sup>3</sup>)-halogen bonds, <b>L</b>CuF is two orders of magnitude more efficient at hydrogen atom abstraction (HAA) than <b>L</b>CuCl and <b>L</b>CuBr. Alongside reported kinetic data for other <b>L</b>Cu(III) species, we established a positive correlation between ligand basicity and the rate of HAA. The capability of <b>L</b>CuF to perform both hydrogen atom abstraction and radical capture was leveraged to enable fluorination of allylic and benzylic C-H bonds and α-C-H bonds of ethers at room temperature.</p>

Mechanistic Borderline of One-Step Hydrogen Atom Transfer versus Stepwise Sc3+-Coupled Electron Transfer from Benzyl Alcohol Derivatives to a Non-Heme Iron(IV)-Oxo Complex

2012 ◽  
Vol 51 (18) ◽  
pp. 10025-10036 ◽  
Author(s):  
Yuma Morimoto ◽  
Jiyun Park ◽  
Tomoyoshi Suenobu ◽  
Yong-Min Lee ◽  
Wonwoo Nam ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Hydrogen Atom ◽  
Benzyl Alcohol ◽  
Hydrogen Atom Transfer ◽  
Heme Iron ◽  
Atom Transfer ◽  
Non Heme Iron ◽  
One Step

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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