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Song Z, Yang R, Liu X, Zhang B, Wu Y. An Organic Molecular Mimetic Metal-Free Heterogeneous Catalyst for Electrocatalytic Alkyne Semihydrogenation. Angew Chem Int Ed Engl 2024; 63:e202410200. [PMID: 39008407 DOI: 10.1002/anie.202410200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2024] [Revised: 07/13/2024] [Accepted: 07/15/2024] [Indexed: 07/17/2024]
Abstract
The direct construction of metal-free catalysts on conductive substrates for electrocatalytic organic hydrogenation reactions is significant but still unexplored. Here, learning from the homogeneous molecular catalysts, an organic molecular mimetic metal-free heterogeneous catalyst is designed and constructed in situ on a graphite flake electrode via a mild electrochemical oxidation-reduction relay strategy. The as-prepared -COOH- and -OH-functionalized metal-free catalyst exhibits an electrocatalytic alkyne semihydrogenation performance with a 72 % Faradaic efficiency, 99 % selectivity and 96 % yield of the alkene product, which is comparable to that of noble metal catalysts. The removal of these oxygen-containing groups leads to negligible activity. The experimental and calculation results reveal that the origin of the high activity can be assigned to the -COOH and -OH groups on graphite. A flow electrolytic cell delivers ten grams of hydrogenated products with 81 % Faradaic efficiency. This metal-free catalyst is also suitable for gas-phase acetylene semihydrogenation and other electrocatalytic hydrogenation reactions.
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Affiliation(s)
- Ziyang Song
- Department of Chemistry, School of Science, Tianjin University, Tianjin, 300072, China
| | - Rong Yang
- Department of Chemistry, School of Science, Tianjin University, Tianjin, 300072, China
| | - Xinyu Liu
- Department of Chemistry, School of Science, Tianjin University, Tianjin, 300072, China
| | - Bin Zhang
- Department of Chemistry, School of Science, Tianjin University, Tianjin, 300072, China
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Frontiers Science Center for Synthetic Biology (Ministry of Education), Tianjin University, Tianjin, 300072, China
| | - Yongmeng Wu
- Department of Chemistry, School of Science, Tianjin University, Tianjin, 300072, China
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Tiddens MR, Kappé BT, Smak TJ, Lutz M, Moret ME. Coordination of a Phosphine-Tethered Aminoborane to Group 10 Metals. Chemistry 2024:e202400666. [PMID: 38577933 DOI: 10.1002/chem.202400666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 04/04/2024] [Accepted: 04/05/2024] [Indexed: 04/06/2024]
Abstract
While π-complexes of C=C bonds are ubiquitous in organometallic chemistry, analogous complexes of the isoelectronic but strongly polarized B=N double bond of aminoboranes are extremely scarce. To address this gap, a diphosphine-aminoborane ligand (PhDPBAiPr) is introduced and its coordination with group 10 metals is investigated. The B=N bond does not coordinate to the metal in Pt(0) and Pd(II) complexes. In contrast, side-on coordination of the B=N bond is observed in the Ni(0) complex (PhDPBAiPr)Ni(NCPh), and the X-ray crystal structure reveals B-N bond elongation compared to the free ligand. The choice of co-ligand strongly influences the presence or absence of side-on coordination at Ni(0) as evidenced by NMR spectroscopy. While the B=N π-complex is geometrically similar to C=C analogues, a bonding analysis reveals that the interaction of the B=N motif with the electron-rich Ni(0) center is best described as 3c4e hyperbond, in which Ni and N are competing for the empty orbital on B.
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Affiliation(s)
- Martine R Tiddens
- Organic Chemistry and Catalysis, Faculty of Science, Utrecht University, Institute for Sustainable and Circular Chemistry, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands
| | - Bram T Kappé
- Organic Chemistry and Catalysis, Faculty of Science, Utrecht University, Institute for Sustainable and Circular Chemistry, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands
| | - Tom J Smak
- Organic Chemistry and Catalysis, Faculty of Science, Utrecht University, Institute for Sustainable and Circular Chemistry, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands
| | - Martin Lutz
- Structural Biochemistry, Faculty of Science, Utrecht University, Bijvoet Centre for Biomolecular Research, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands
| | - Marc-Etienne Moret
- Organic Chemistry and Catalysis, Faculty of Science, Utrecht University, Institute for Sustainable and Circular Chemistry, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands
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Czaikowski ME, Anferov SW, Tascher AP, Anderson JS. Electrocatalytic Semihydrogenation of Terminal Alkynes Using Ligand-Based Transfer of Protons and Electrons. J Am Chem Soc 2024; 146:476-486. [PMID: 38163759 DOI: 10.1021/jacs.3c09885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
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 H2 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 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 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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Affiliation(s)
- Maia E Czaikowski
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - Sophie W Anferov
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - Alex P Tascher
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - John S Anderson
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
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Sansores-Paredes MG, Nguyen TTT, Lutz M, Moret ME. Reactions of Nickel(0)-Olefin Pincer Complexes with Terminal Alkynes: Cooperative C-H Bond Activation and Alkyne Coupling. Organometallics 2023; 42:3418-3427. [PMID: 38098646 PMCID: PMC10716905 DOI: 10.1021/acs.organomet.3c00404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 11/06/2023] [Accepted: 11/06/2023] [Indexed: 12/17/2023]
Abstract
Metal-ligand cooperation can facilitate the activation of chemical bonds, opening reaction pathways of interest for catalyst development. In this context, olefins occupying the central position of a diphosphine pincer ligand (PC=CP) are emerging as reversible H atom acceptors, e.g., for H2 activation. Here, we report on the reactivity of nickel complexes of PC=CP ligands with a terminal alkyne, for which two competing pathways are observed. First, cooperative and reversible C-H bond activation generates a Ni(II) alkyl/alkynyl complex as the kinetic product. Second, in the absence of a bulky substituent on the olefin, two alkyne molecules are incorporated in the ligand structure to form a conjugated triene bound to Ni(0). The mechanisms of these processes are studied by density functional theory calculations supported by experimental observations.
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Affiliation(s)
- María
L. G. Sansores-Paredes
- Organic
Chemistry and Catalysis, Institute for Sustainable and Circular Chemistry,
Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Tú T. T. Nguyen
- Organic
Chemistry and Catalysis, Institute for Sustainable and Circular Chemistry,
Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Martin Lutz
- Structural
Biochemistry, Bijvoet Centre for Biomolecular Research, Faculty of
Science, Utrecht University, Universiteitsweg 99, 3534 CG Utrecht, The Netherlands
| | - Marc-Etienne Moret
- Organic
Chemistry and Catalysis, Institute for Sustainable and Circular Chemistry,
Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
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