Copper(I)/NO(g) Reductive Coupling Producing a trans-Hyponitrite Bridged Dicopper(II) Complex: Redox Reversal Giving Copper(I)/NO(g) Disproportionation

Wijeratne, Gayan B.; Hematian, Shabnam; Siegler, Maxime A.; Karlin, Kenneth D.

doi:10.1021/jacs.7b07808

Cited by 46 publications

(91 citation statements)

References 51 publications

(55 reference statements)

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“…The stability of the title compounds was not in line with the usual classification of the hydrogenhyponitrite ion as an intermediate towards nitrous-oxide formation. [12,18,19,30] However,a closer look at space-filling modelso f5-7 showed that the phenylg roups of the bisphosphanel igands enclosed the hydrogenhyponitrite/hyponitrite ligand and the ruthenium(II) center ( Figure 13).…”

Section: Differencementioning

confidence: 99%

“…[13,17] Cobalt, copper,i ron, ruthenium,a nd yttrium form polynuclear cis-a nd trans-hyponitrito complexes. [12,[14][15][16][18][19][20] There is only one type of coordinated hydrogenhyponitrite known.B çttchere tal. synthesized ad iruthenium(I) complex, bridged with sterically demanding phosphide ligands, which is capable of reducing nitric oxide to ab ridging hyponitrite ligand according to [Ru 2 (CO) 4 (m-dppm)(m-H)(m-PtBu 2 )] + 2NO!…”

Section: Introductionmentioning

confidence: 99%

“…Some characteristics of hyponitrite coordination are visible: the group 10 metals, nickel and platinum, provide a suitable environment for mononuclear cis ‐hyponitrito complexes . Cobalt, copper, iron, ruthenium, and yttrium form polynuclear cis ‐ and trans ‐hyponitrito complexes …”

Section: Introductionmentioning

confidence: 99%

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HN₂O₂⁻ as a Ligand in Mononuclear Hydrogenhyponitrite‐κ²‐N,O Ruthenium Complexes with Bisphosphane Co‐Ligands

Beck

Klüfers

2018

Chemistry A European J

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The hyponitrite anion is a tentative intermediate in the reduction of nitric oxide (NO) to nitrous oxide (N O) catalyzed by nitric-oxide reductase (NOR) in the process of bacterial denitrification. Owing to the considerable number of known coordination modes for the hyponitrito ligand, its actual bonding form in the enzymatic cycle is a point of current discussion. Here, we contribute to the hardly known ligand properties of a key intermediate, the monoprotonated hyponitrite anion. Three air- and water-stable ruthenium complexes with hydrogenhyponitrite as the ligand were synthesized by using commercially available bisphosphane co-ligands (1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), 1,2-bis(diphenylphosphino)ethene (dppv)). The starting compounds [Ru(dppe) (tos)]BF (1) and [Ru(dppp) (tos)]BF (2) contained the bidentate coordinating tosylate anion (tos) as a particularly well-suited leaving group. To confirm the protonated and deprotonated species, X-ray diffraction, IR, UV/Vis spectroscopy (solution and solid state), solid-state NMR spectroscopy, and high-resolution mass spectroscopy were used. DFT calculations give insight into the bonding situation. We report on [Ru(dppe) (HN O )]BF (5), [Ru(dppp) (HN O )]BF (6), [Ru(dppv) (HN O )]BF (7), [Ru(dppp) (HN O )]BF ⋅Imi (9; Imi=imidazole) as the first mononuclear trans-hydrogenhyponitrite complexes. Isolated deprotonated analogs are [Ru(dppe) (N O )]⋅HImi(BF ) (8) and [Ru(dppv) (N O )] ⋅HImi(BF )⋅Imi (10).

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Section: Differencementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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HN₂O₂⁻ as a Ligand in Mononuclear Hydrogenhyponitrite‐κ²‐N,O Ruthenium Complexes with Bisphosphane Co‐Ligands

Beck

Klüfers

2018

Chemistry A European J

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“…Nitric oxide (NO) reduction, known as the process of relieving nitrosative stress for pathogenic bacteria and fungi, is central to the regulation of NO x levels . Biomimetic model studies suggest that NO reduction yielding N 2 O may occur via hyponitrite [N 2 O 2 ] 2− ‐bound intermediate, generated by inter−/intra‐molecular (O)N–N(O) coupling reaction of two reduced metal‐NO units ({Fe(NO)} 7/8 ) or coupling of metal‐[NO] 2− unit with exogenous NO gas . It was demonstrated that NO ligands bound to Fe in mononuclear dinitrosyl iron complexes, existing in cells as intrinsic NO‐storage/−transport species in the biological systems, do not voluntarily form a reductive coupling product (hyponitrite), due to their spin‐parallel electronic structure of two NO‐coordinated ligands in [Fe(NO) 2 ] unit .…”

Section: Discussionmentioning

confidence: 99%

“…This result demonstrates that H‐bonding interactions are required to stabilize N‐N bond of hyponitrite. Furthermore, Karlin et al proposed that the hyponitrite – bridged dicopper complex [{Cu(tmpa)} 2 ( μ ‐N 2 O 2 )] 2+ was generated by introducing exogenous NO to [Cu(tmpa)(MeCN)](B[C 6 F 5 ] 4 ) in methanol at room temperature, as shown in Scheme . However, replacing reaction solution with THF results in NO disproportionation to yield Cu ‐ nitrito complex [{Cu(tmpa)} 2 (NO 2 )] + accompanied by release of N 2 O.…”

Section: Metal‐hyponitrite Complexes Stabilized By Hydrogen Bondingmentioning

confidence: 99%

Nitric oxide reduction forming hyponitrite triggered by metal‐containing complexes

Liaw

2020

J Chinese Chemical Soc

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Nitric oxide reduction yielding N2O is known as a route to detoxify nitric oxide (NO) to relieve nitrosative stress in pathogenic bacteria and fungi. Nitric oxide enzymes are classified into Cu/Fe‐heme NO reductases (NORs) and non‐heme flavindiiron NO reductases (FNORs). In biological system, the mechanism of NO reduction generating N2O was proposed to involve NO coordination to metal centers prior to producing cis/trans‐hyponitrite‐bound intermediate, and the subsequent protonation of hyponitrite‐bound‐Fe/Cu intermediates releases N2O. In this review article, we compile the recently published biomimetic model studies of NO‐to‐[N2O2]2− transformation triggered by the designed transition‐metal complexes. In biomimetic model study, the ON‐NO bond coupling of metal‐nitrosyl complexes yielding [N2O2]2−‐bound species may occur via either the inter/intramolecular radical‐[NO]−‐radical‐[NO]− coupling or metal‐[NO]2− radical coupling with exogenous NO˙. The H‐bonding interaction between hyponitrite and protic solvents promoting/stabilizing the formation of hyponitrite complexes was also demonstrated. In addition, the electronic structure of the designed transition‐metal‐nitrosyl complexes triggering the formation of [N2O2]2−‐bound species and the detailed NO‐to‐[N2O2]2− formation pathways were delineated.

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Reductive Nitric Oxide Coupling at a Dinickel Core: Isolation of a Key cis‐Hyponitrite Intermediate en route to N₂O Formation

Ferretti¹,

Dechert²,

Demeshko³

et al. 2019

Angewandte Chemie

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Reductive coupling of nitric oxide (NO) to give N2O is an important reaction in the global nitrogen cycle. Here, a dinickel(II) dihydride complex 1 that releases H2 upon substrate binding and serves as a masked dinickel(I) scaffold is shown to reductively couple two molecules of NO within the bimetallic cleft. The resulting hyponitrite complex 2 features an unprecedented cis‐[N2O2]2− binding mode that has been computationally proposed as a key intermediate in flavodiiron nitric oxide reductases (FNORs). NMR and DFT evidence indicate facile rotational fluxionality of the [N2O2]2− unit, which allows to access an isomer that is prone to N2O release. Protonation of 2 is now found to trigger rapid N2O evolution and formation of a hydroxido bridged complex, reminiscent of FNOR reactivity. This work provides fundamental insight into the biologically relevant reductive coupling of two NO molecules and the subsequent trajectory towards N2O formation at bimetallic sites.

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Copper(I)/NO_(g) Reductive Coupling Producing a trans-Hyponitrite Bridged Dicopper(II) Complex: Redox Reversal Giving Copper(I)/NO_(g) Disproportionation

Cited by 46 publications

References 51 publications

HN₂O₂⁻ as a Ligand in Mononuclear Hydrogenhyponitrite‐κ²‐N,O Ruthenium Complexes with Bisphosphane Co‐Ligands

HN₂O₂⁻ as a Ligand in Mononuclear Hydrogenhyponitrite‐κ²‐N,O Ruthenium Complexes with Bisphosphane Co‐Ligands

Nitric oxide reduction forming hyponitrite triggered by metal‐containing complexes

Reductive Nitric Oxide Coupling at a Dinickel Core: Isolation of a Key cis‐Hyponitrite Intermediate en route to N₂O Formation

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Copper(I)/NO(g) Reductive Coupling Producing a trans-Hyponitrite Bridged Dicopper(II) Complex: Redox Reversal Giving Copper(I)/NO(g) Disproportionation

Cited by 46 publications

References 51 publications

HN2O2− as a Ligand in Mononuclear Hydrogenhyponitrite‐κ2‐N,O Ruthenium Complexes with Bisphosphane Co‐Ligands

HN2O2− as a Ligand in Mononuclear Hydrogenhyponitrite‐κ2‐N,O Ruthenium Complexes with Bisphosphane Co‐Ligands

Nitric oxide reduction forming hyponitrite triggered by metal‐containing complexes

Reductive Nitric Oxide Coupling at a Dinickel Core: Isolation of a Key cis‐Hyponitrite Intermediate en route to N2O Formation

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Copper(I)/NO_(g) Reductive Coupling Producing a trans-Hyponitrite Bridged Dicopper(II) Complex: Redox Reversal Giving Copper(I)/NO_(g) Disproportionation

HN₂O₂⁻ as a Ligand in Mononuclear Hydrogenhyponitrite‐κ²‐N,O Ruthenium Complexes with Bisphosphane Co‐Ligands

HN₂O₂⁻ as a Ligand in Mononuclear Hydrogenhyponitrite‐κ²‐N,O Ruthenium Complexes with Bisphosphane Co‐Ligands

Reductive Nitric Oxide Coupling at a Dinickel Core: Isolation of a Key cis‐Hyponitrite Intermediate en route to N₂O Formation