Electrochemical and catalytic properties of nickel(II) complexes with bis(imino)acenaphthene and diazadiphosphacyclooctane ligands

Khrizanforova, Vera V.; Fayzullin, Robert R.; Musina, Elvira I.; Карасик, А. А.; Budnikova, Yulia H.

doi:10.1016/j.mencom.2020.05.013

Cited by 11 publications

(3 citation statements)

References 36 publications

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“…This approach has afforded several catalysts for the oxidation of hydrogen but has not resulted in many new catalysts for hydrogen production. Heteroleptic complexes containing one P 2 N 2 ligand and a second diphosphine with no pendant amine are prone to redistribute into a mixture of complexes with two of the same ligand. , Use of a bulky t -Bu group at phosphorus allows for the synthesis of [Ni(P t Bu 2 N R′ 2 )(MeCN) 2 ] 2+ , but these complexes are unstable in the presence of weak organic acids . A stable hydrogen production catalyst was obtained with a tetradentate phosphine ligand possessing a P 2 N 2 moiety in the ligand backbone (Figure ).…”

Section: Electrocatalytic Production Of H2 With [Ni(p2n2)2]2+ Complexesmentioning

confidence: 99%

Molecular Catalysts with Diphosphine Ligands Containing Pendant Amines

et al. 2022

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Pendant amines play an invaluable role in chemical reactivity, especially for molecular catalysts based on earth-abundant metals. As inspired by [FeFe]-hydrogenases, which contain a pendant amine positioned for cooperative bifunctionality, synthetic catalysts have been developed to emulate this multifunctionality through incorporation of a pendant amine in the second coordination sphere. Cyclic diphosphine ligands containing two amines serve as the basis for a class of catalysts that have been extensively studied and used to demonstrate the impact of a pendant base. These 1,5-diaza-3,7-diphosphacyclooctanes, now often referred to as “P2N2” ligands, have profound effects on the reactivity of many catalysts. The resulting [Ni(PR 2NR′ 2)2]2+ complexes are electrocatalysts for both the oxidation and production of H2. Achieving the optimal benefit of the pendant amine requires that it has suitable basicity and is properly positioned relative to the metal center. In addition to the catalytic efficacy demonstrated with [Ni(PR 2NR′ 2)2]2+ complexes for the oxidation and production of H2, catalysts with diphosphine ligands containing pendant amines have also been demonstrated for several metals for many different reactions, both in solution and immobilized on surfaces. The impact of pendant amines in catalyst design continues to expand.

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Section: Electrocatalytic Production Of H2 With [Ni(p2n2)2]2+ Complexesmentioning

confidence: 99%

Molecular Catalysts with Diphosphine Ligands Containing Pendant Amines

et al. 2022

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“…This catalytic response is due to H 2 evolution and we note that many Ni catalysts are known to be active electrocatalysts for this reaction (Figure S60). − …”

Section: Resultsmentioning

confidence: 99%

Electrocatalytic Semihydrogenation of Terminal Alkynes Using Ligand-Based Transfer of Protons and Electrons

Czaikowski,

Anferov,

Tascher

et al. 2024

J. Am. Chem. Soc.

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Alkyne semihydrogenation is a broadly important transformation in chemical synthesis. Here, we introduce an electrochemical method for the selective semihydrogenation of terminal alkynes using a dihydrazonopyrrole Ni complex capable of storing an H 2 equivalent (2H + + 2e − ) on the ligand backbone. This method is chemoselective for the semihydrogenation of terminal alkynes over internal alkynes or alkenes. Mechanistic studies reveal that the transformation is concerted and Zselective. Calculations support a ligand-based hydrogen-atom transfer pathway instead of a hydride mechanism, which is commonly invoked for transition metal hydrogenation catalysts. The synthesis of the proposed intermediates demonstrates that the catalytic mechanism proceeds through a reduced formal Ni(I) species. The high yields for terminal alkene products without over-reduction or oligomerization are among the best reported for any homogeneous catalyst. Furthermore, the metal−ligand cooperative hydrogen transfer enabled with this system directs the efficient flow of H atom equivalents toward alkyne reduction rather than hydrogen evolution, providing a blueprint for applying similar strategies toward a wide range of electroreductive transformations.

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“…This catalytic response is due to H2 evolution and we note that many Ni catalysts are known to be active electrocatalysts for this reaction (Figure S57). [49][50][51][52][53][54][55][56][57][58][59][60] Despite the potential for H2 evolution side reactivity, we still wanted to test whether the net H + and e − equivalents delivered electrochemically could be harnessed for hydrogenation reactivity. Indeed, upon addition of 1-octyne, the catalytic feature at -1.5 V vs Fc 0/+ is suppressed and adopts a new waveform consistent with a change in reactivity in the presence of an alkyne substrate (Figure 2B).…”

Section: Electrochemical Characterizationmentioning

confidence: 99%

Electrocatalytic Semi-Hydrogenation of Terminal Alkynes using Ligand-Based Transfer of Protons and Electrons

Czaikowski,

Anferov,

Tascher

et al. 2023

Preprint

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Alkyne semi-hydrogenation is a broadly important transformation in chemical synthesis. Here, we introduce an electrochemical method for the selective semi-hydrogenation of terminal alkynes using a dihydrazonopyrrole Ni complex capable of storing an H2 equivalent (2H+ + 2e–) on the ligand backbone. This method is chemoselective for the semi-hydrogenation of terminal alkynes over internal alkynes or alkenes. Mechanistic studies reveal that the transformation is concerted and Z-selective. Calculations support a ligand-based hydrogen-atom transfer pathway instead of a hydride mechanism which is commonly invoked for transition metal hydrogenation catalysts. The synthesis of proposed intermediates demonstrates that the catalytic mechanism proceeds through a reduced formally Ni(I) species. The high yields for terminal alkene products without overreduction or oligomerization are among the best reported for any homogeneous catalyst. Furthermore, the metal-ligand cooperative hydrogen transfer enabled with this system directs the efficient flow of H-atom equivalents toward alkyne reduction rather than hydrogen evolution, providing a blueprint for applying similar strategies towards a wide range of electroreductive transformations.

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Electrochemical and catalytic properties of nickel(II) complexes with bis(imino)acenaphthene and diazadiphosphacyclooctane ligands

Cited by 11 publications

References 36 publications

Molecular Catalysts with Diphosphine Ligands Containing Pendant Amines

Molecular Catalysts with Diphosphine Ligands Containing Pendant Amines

Electrocatalytic Semihydrogenation of Terminal Alkynes Using Ligand-Based Transfer of Protons and Electrons

Electrocatalytic Semi-Hydrogenation of Terminal Alkynes using Ligand-Based Transfer of Protons and Electrons

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