Catalytic hydrogenation enabled by ligand-based storage of hydrogen

McNeece, Andrew J.; Jesse, Kate; Filatov, Alexander S.; Schneider, Joseph; Anderson, John S.

doi:10.1039/d0cc08236h

Cited by 17 publications

(30 citation statements)

References 36 publications

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“…We reasoned that the previously reported pyrrole-based ligand scaffold t Bu,Tol DHP ( t Bu,Tol DHP = 2,5-bis((2- t -butylhydrazono)( p -tolyl)methyl)-pyrrole, Scheme 1 ), which can donate two electrons and two protons to a substrate, would be an ideal scaffold to demonstrate this principle. 69 Here, we show that the preorganization of protons and electrons on this ligand scaffold allows for the direct formation of an Fe(III)-hydroperoxo intermediate from O 2 , mirroring the type of reactivity and preorganization found in the protein superstructure of biological systems. This Fe(III)-hydroperoxo intermediate has been characterized by a variety of spectroscopic techniques in addition to kinetic and computational analysis.…”

Section: Introductionsupporting

confidence: 54%

Direct Aerobic Generation of a Ferric Hydroperoxo Intermediate Via a Preorganized Secondary Coordination Sphere

et al. 2021

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Enzymes exert control over the reactivity of metal centers with precise tuning of the secondary coordination sphere of active sites. One particularly elegant illustration of this principle is in the controlled delivery of proton and electron equivalents in order to activate abundant but kinetically inert oxidants such as O 2 for oxidative chemistry. Chemists have drawn inspiration from biology in designing molecular systems where the secondary coordination sphere can shuttle protons or electrons to substrates. However, a biomimetic activation of O 2 requires the transfer of both protons and electrons, and molecular systems where ancillary ligands are designed to provide both of these equivalents are comparatively rare. Here, we report the use of a dihydrazonopyrrole (DHP) ligand complexed to Fe to perform exactly such a biomimetic activation of O 2 . In the presence of O 2 , this complex directly generates a high spin Fe(III)-hydroperoxo intermediate which features a DHP • ligand radical via ligand-based transfer of an H atom. This system displays oxidative reactivity and ultimately releases hydrogen peroxide, providing insight on how secondary coordination sphere interactions influence the evolution of oxidizing intermediates in Fe-mediated aerobic oxidations.

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Section: Introductionsupporting

confidence: 54%

Direct Aerobic Generation of a Ferric Hydroperoxo Intermediate Via a Preorganized Secondary Coordination Sphere

et al. 2021

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show abstract

“…We reasoned that the previously reported pyrrolebased ligand scaffold tBu,Tol DHP ( tBu,Tol DHP = 2,5-bis((2-tbutylhydrazono)(p-tolyl)methyl)-pyrrole, Scheme 1), which can donate two electrons and two protons to a substrate, would be an ideal scaffold to demonstrate this principle. 69 Here, we show that the preorganization of protons and electrons on this ligand scaffold allows for the direct formation of an Fe(III)-hydroperoxo intermediate from O 2 , mirroring the type of reactivity and preorganization found in the protein superstructure of biological systems. This Fe(III)-hydroperoxo intermediate has been characterized by a variety of spectroscopic techniques in addition to kinetic and computational analysis.…”

Section: ■ Introductionsupporting

confidence: 54%

Direct Aerobic Generation of a Ferric Hydroperoxo Intermediate via a Preorganized Secondary Coordination Sphere

Jesse

Anferov

Collins³

et al. 2021

Preprint

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Enzymes exert control over the reactivity of metal centers with precise tuning of the secondary coordination sphere of active sites. One particularly elegant illustration of this principle is in the controlled delivery of proton and electron equivalents in order to activate abundant but kinetically inert oxidants such as O2 for oxidative chemistry. Chemists have drawn inspiration from biology in designing molecular systems where the secondary coordination sphere can shuttle protons or electrons to substrates. However, a biomimetic activation of O2 requires the transfer of both protons and elec-trons, and molecular systems where ancillary ligands are designed to provide both of these equivalents are comparative-ly rare. Here we report the use of a dihydrazonopyrrole (DHP) ligand complexed to Fe to perform exactly such a biomi-metic activation of O2. In the presence of O2, this complex directly generates a high spin Fe(III)-hydroperoxo intermediate which features a DHP• ligand radical via ligand-based transfer of an H-atom. This system displays oxidative reactivity and ultimately releases hydrogen peroxide, providing insight on how secondary coordination sphere interactions influence the evolution of oxidizing intermediates in Fe-mediated aerobic oxidations.

show abstract

“…We reasoned that the previously reported pyrrole-based ligand scaffold tBu,Tol DHP ( tBu,Tol DHP = 2,5bis((2-t-butylhydrazono)(p-tolyl)methyl)-pyrrole, Scheme 1), which can donate two electrons and two protons to a substrate, would be an ideal scaffold to demonstrate this principle. 69 Here we show that the preorganization of protons and electrons on this ligand scaffold allows for the direct formation of an Fe(III)-hydroperoxo intermediate from O2, mirroring the type of reactivity and Scheme 1. Metalation of tBu,Tol DHP-H2•2HCl with FeCl2.…”

Section: Enzymaticmentioning

confidence: 55%

“…This presence of a low energy absorbance was previously seen with isolated tBu/Ph,Tol DHP ligand radicals on Ni and Fe centers, further supporting the assignment of 3 with a ligand based radical on tBu,Tol DHP-H • (Scheme 2). 53,69,86…”

Section: Computational Analysis Ofmentioning

confidence: 99%

Direct Aerobic Generation of a Ferric Hydroperoxo Intermediate via a Preorganized Secondary Coordination Sphere

Jesse

Anferov

Collins³

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

Enzymes exert control over the reactivity of metal centers with precise tuning of the secondary coordination sphere of active sites. One particularly elegant illustration of this principle is in the controlled delivery of proton and electron equivalents in order to activate abundant but kinetically inert oxidants such as O2 for oxidative chemistry. Chemists have drawn inspiration from biology in designing molecular systems where the secondary coordination sphere can shuttle protons or electrons to substrates. However, a biomimetic activation of O2 requires the transfer of both protons and electrons, and molecular systems where ancillary ligands are designed to provide both of these equivalents are comparatively rare. Here we report the use of a dihydrazonopyrrole (DHP) ligand complexed to Fe to perform exactly such a biomimetic activation of O2. In the presence of O2, this complex directly generates a high spin Fe(III)-hydroperoxo intermediate which features a DHP • ligand radical via ligand-based transfer of an H-atom. This system displays oxidative reactivity and ultimately releases hydrogen peroxide, providing insight on how secondary coordination sphere interactions influence the evolution of oxidizing intermediates in Fe-mediated aerobic oxidations.

show abstract

Catalytic hydrogenation enabled by ligand-based storage of hydrogen

Abstract: Biology employs exquisite control over proton, electron, H-atom, or H2 transfer. Similar control in synthetic systems has the potential to facilitate efficient and selective catalysis. Here we report a dihydrazonopyrrole...

Cited by 17 publications

References 36 publications

Direct Aerobic Generation of a Ferric Hydroperoxo Intermediate Via a Preorganized Secondary Coordination Sphere

Direct Aerobic Generation of a Ferric Hydroperoxo Intermediate Via a Preorganized Secondary Coordination Sphere

Direct Aerobic Generation of a Ferric Hydroperoxo Intermediate via a Preorganized Secondary Coordination Sphere

Direct Aerobic Generation of a Ferric Hydroperoxo Intermediate via a Preorganized Secondary Coordination Sphere

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