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Abstract Significant progress has been made in the bioinorganic modeling of the paramagnetic states believed to be involved in the hydrogen redox chemistry catalyzed by [NiFe] hydrogenase. However, the characterization and isolation of intermediates involved in mononuclear Ni electrocatalysts which are reported to operate through a NiI/IIIcycle have largely remained elusive. Herein, we report a NiIIcomplex (NCHS2)Ni(OTf)2, where NCHS2 is 3,7-dithia-1(2,6)-pyridina-5(1,3)-benzenacyclooctaphane, that is an efficient electrocatalyst for the hydrogen evolution reaction (HER) with turnover frequencies of ~3,000 s−1and a overpotential of 670 mV in the presence of trifluoroacetic acid. This electrocatalyst follows a hitherto unobserved HER mechanism involving C-H activation, which manifests as an inverse kinetic isotope effect for the overall hydrogen evolution reaction, and NiI/NiIIIintermediates, which have been characterized by EPR spectroscopy. We further validate the possibility of the involvement of NiIIIintermediates by the independent synthesis and characterization of organometallic NiIIIcomplexes.
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Enantioselective Synthesis of Functionalized Arenes by Nickel‐Catalyzed Site‐Selective Hydroarylation of 1,3‐Dienes with Aryl Boronates
Abstract A catalytic method for the site‐selective and enantioselective synthesis of functionalized arenes by the intermolecular hydroarylation of terminal and internal 1,3‐dienes with aryl pinacolato boronates is reported. The reactions are promoted by 5.0 mol % of a readily available monodentate phosphoramidite‐Ni complex in ethanol, affording a variety of enantioenriched products in up to 96 % yield and 99:1 er. Mechanistic studies indicate that Ni–allyl formation is irreversible and related to the nature of the arylboronate.
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- Award ID(s):
- 1665125
- PAR ID:
- 10158923
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- Volume:
- 59
- Issue:
- 33
- ISSN:
- 1433-7851
- Page Range / eLocation ID:
- p. 14070-14075
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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