The coordination chemistry of acyclic pentadentate pentaamine ligands

Blackman, Allan G.

doi:10.1016/j.poly.2018.12.004

Cited by 8 publications

(5 citation statements)

References 313 publications

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“…Although a variety of different achiral pentadentate ligands and their corresponding iron complexes have been reported, , there are surprisingly few reports on the synthesis of well-defined chiral iron complexes from chiral pentadentate ligands − and only a handful of reports on asymmetric catalysis with chiral pentadentate iron complexes. One of the first examples was reported by the Ohno group.…”

Section: Resultsmentioning

confidence: 99%

Stereogenic-at-Iron Catalysts with a Chiral Tripodal Pentadentate Ligand

et al. 2021

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A class of stereogenic-at-iron catalysts is introduced and applied to asymmetric 3d-transition metal catalysis. The pentadentate coordination of a tripodal ligand creates a stereogenic iron center, while an isopropyl group in the ligand backbone serves as a chiral lever to thermodynamically favor one diastereomer (>20:1 dr) of the obtained iron complexes. The coordination sphere is completed with a labile acetonitrile ligand. Ligand coordination and dynamics were studied by NMR spectroscopy. A modular design of the tripodal ligand enables the convenient implementation of different modifications, which have been incorporated and investigated in this work. The catalytic performance of the obtained complexes was evaluated in the ring contraction of isoxazoles to chiral 2H-azirines in up to 99% yield and with up to 93% ee and features a remarkably high catalytic activity with up to 10,000 turnover numbers (TON).

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Section: Resultsmentioning

confidence: 99%

Stereogenic-at-Iron Catalysts with a Chiral Tripodal Pentadentate Ligand

et al. 2021

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“…Since demetalation of Cu(I) is a common deactivation pathway in Cu Z * synthetic models, we rationalized that polydentate chelates with strong N donors could minimize the loss of this labile metal. , We previously reported a Co(II) compound supported by a tip(Me) ligand (tip(Me) = 2,6-(bis(bis-2- N -methylimidazolyl)-hydroxymethyl)pyridine) for electrocatalytic water oxidation featuring strongly donating imidazole arms . We hypothesized that strongly donating imidazole arms would chelate the metal more strongly versus other N5 polypyridyl ligands such as PY5Me 2 (PY5Me 2 = 2,6-bis(1,1-bis(2-pyridyl)ethyl)pyridine). − We aimed to further redesign this ligand to remove the acidic hydroxyl groups and to increase synthetic ease by replacing the carbon bridgeheads with P atoms. This new tetraimidazolyl-substituted pyridine ligand, MeIm 4 P 2 Py (MeIm 4 P 2 Py = 2,6-(bis(bis-2- N -methylimidazolyl)phosphino)pyridine, 1 ), was synthesized by adapting a previously described one-pot reaction between a dichlorophosphine and an N -alkyl imidazole (Scheme ).…”

Section: Resultsmentioning

confidence: 99%

“… 50 We hypothesized that strongly donating imidazole arms would chelate the metal more strongly versus other N5 polypyridyl ligands such as PY5Me 2 (PY5Me 2 = 2,6-bis(1,1-bis(2-pyridyl)ethyl)pyridine). 51 − 54 We aimed to further redesign this ligand to remove the acidic hydroxyl groups and to increase synthetic ease by replacing the carbon bridgeheads with P atoms. This new tetraimidazolyl-substituted pyridine ligand, MeIm 4 P 2 Py (MeIm 4 P 2 Py = 2,6-(bis(bis-2- N -methylimidazolyl)phosphino)pyridine, 1 ), was synthesized by adapting a previously described one-pot reaction between a dichlorophosphine and an N -alkyl imidazole ( Scheme 1 ).…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Reduction of N₂O with a Molecular Copper Catalyst

Martinez,

Schneider,

Anferov

et al. 2023

ACS Catal.

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Deoxygenation of nitrous oxide (N 2 O) has significant environmental implications, as it is not only a potent greenhouse gas but is also the main substance responsible for the depletion of ozone in the stratosphere. This has spurred significant interest in molecular complexes that mediate N 2 O deoxygenation. Natural N 2 O reduction occurs via a Cu cofactor, but there is a notable dearth of synthetic molecular Cu catalysts for this process. In this work, we report a selective molecular Cu catalyst for the electrochemical reduction of N 2 O to N 2 using H 2 O as the proton source. Cyclic voltammograms show that increasing the H 2 O concentration facilitates the deoxygenation of N 2 O, and control experiments with a Zn(II) analogue verify an essential role for Cu. Theory and spectroscopy support metal−ligand cooperative catalysis between Cu(I) and a reduced tetraimidazolyl-substituted radical pyridine ligand (MeIm 4 P 2 Py = 2,6-(bis(bis-2-N-methylimidazolyl)phosphino)pyridine), which can be observed by Electron Paramagnetic Resonance (EPR) spectroscopy. Comparison with biological processes suggests a common theme of supporting electron transfer moieties in enabling Cu-mediated N 2 O reduction.

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“…50 We hypothesized that strongly donating imidazole arms would chelate the metal more strongly vs. other N5 polypyridyl ligands such as PY5Me2 (PY5Me2 = 2,6-bis(1,1-bis(2pyridyl)ethyl)pyridine). [51][52][53][54] We aimed to further redesign this ligand to remove the acidic hydroxyl groups and to increase synthetic ease by replacing the carbon bridgeheads with P-atoms. This new tetraimidazolyl substituted pyridine ligand, MeIm4P2Py (MeIm4P2Py = 2,6-(bis(bis-2-N-methylimidazolyl)phosphino)pyridine , 1), was synthesized by adapting a previously described one-pot reaction between a dichlorophosphine and an N-alkyl imidazole.…”

Section: Catalyst Synthesis and Characterizationmentioning

confidence: 99%

Electrochemical Reduction of N2O with a Molecular Copper Catalyst

Martínez

Schneider

Anferov

et al. 2023

Preprint

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Deoxygenation of nitrous oxide (N2O) has significant environmental implications as it is not only a potent greenhouse gas but is also the main substance responsible for the depletion of ozone in the stratosphere. This has spurred significant interest in molecular complexes that mediate N2O deoxygenation. Natural N2O reduction occurs via a Cu cofactor but there is a notable dearth of synthetic molecular Cu catalysts for this process. In this work, we report a selective molecular Cu catalyst for the electrochemical reduction of N2O to N2 using H2O as a proton source. Cyclic voltammograms show that increasing H2O concentration facilitates deoxygenation of N2O and control experiments with a Zn(II) analog verify an essential role for Cu. Theory and spectroscopy support metal-ligand cooperative catalysis between Cu(I) and a reduced tetraimidazolyl substituted radical pyridine ligand, (MeIm4P2Py = 2,6-(bis(bis-2-N-methylimidazolyl)phosphino)pyridine) which can be observed by Electron Paramagnetic Resonance (EPR) spectroscopy. Comparison with biological processes suggests a common theme of supporting electron transfer moieties in enabling Cu-mediated N2O reduction

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The coordination chemistry of acyclic pentadentate pentaamine ligands

Cited by 8 publications

References 313 publications

Stereogenic-at-Iron Catalysts with a Chiral Tripodal Pentadentate Ligand

Stereogenic-at-Iron Catalysts with a Chiral Tripodal Pentadentate Ligand

Electrochemical Reduction of N₂O with a Molecular Copper Catalyst

Electrochemical Reduction of N2O with a Molecular Copper Catalyst

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