1
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Borowski JE, Newman-Stonebraker SH, Doyle AG. Comparison of Monophosphine and Bisphosphine Precatalysts for Ni-Catalyzed Suzuki-Miyaura Cross-Coupling: Understanding the Role of the Ligation State in Catalysis. ACS Catal 2023; 13:7966-7977. [PMID: 38037565 PMCID: PMC10688240 DOI: 10.1021/acscatal.3c01331] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2023]
Abstract
Practical advances in Ni-catalyzed Suzuki-Miyaura cross-coupling (SMC) have been limited by a lack of mechanistic understanding of phosphine ligand effects. While bisphosphines are commonly used in these methodologies, we have observed instances where monophosphines can provide comparable or higher levels of reactivity. Seeking to understand the role of ligation state in catalysis, we performed a head-to-head comparison study of C(sp2)-C(sp2) Ni SMCs catalyzed by mono and bisphosphine precatalysts using six distinct substrate pairings. Significant variation in optimal precatalyst was observed, with the monophosphine precatalyst tending to outperform the bisphosphines with electronically deactivated and sterically hindered substrates. Mechanistic experiments revealed a role for monoligated (P1Ni) species in accelerating the fundamental organometallic steps of the catalytic cycle, while highlighting the need for bisligated (P2Ni) species to avoid off-cycle reactivity and catalyst poisoning by heterocyclic motifs. These findings provide guidelines for ligand selection against challenging substrates and future ligand design tailored to the mechanistic demands of Ni-catalyzed SMCs.
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Affiliation(s)
| | - Samuel H. Newman-Stonebraker
- Department of Chemistry, Princeton University, Princeton, NJ 08544
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095
| | - Abigail G. Doyle
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095
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2
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Hannigan MD, Tami JL, Zimmerman PM, McNeil AJ. Rethinking Catalyst Trapping in Ni-Catalyzed Thieno[3,2- b]thiophene Polymerization. Macromolecules 2022; 55:10821-10830. [PMID: 37396500 PMCID: PMC10312364 DOI: 10.1021/acs.macromol.2c01521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Catalyst-transfer polymerization (CTP) is a chain-growth method used to synthesize conjugated polymers. Although CTP works well for most donor-type monomers, the polymerization stalls with thieno[3,2-b]thiophene when using Ni catalysts. Previous reports have rationalized this result by suggesting that the catalyst is trapped in a Ni0 π-complex with the highly electron-rich arene. In this study, evidence is provided that the catalyst trap is more likely a NiII complex that arises from oxidative insertion of Ni0 into the C-S bonds of thieno[3,2-b]thiophene. This result is consistent with the known reactivity of Ni0 complexes toward S-heteroarenes and is supported herein by 31P nuclear magnetic resonance spectra acquired in situ, as well as data collected from small-molecule model reactions and density-functional theory simulations of the polymerization. We propose that this C-S insertion pathway and related off-cycle reactions may be relevant to understanding or enabling the CTP of other monomers with fused thiophenes.
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Affiliation(s)
- Matthew D Hannigan
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Jessica L Tami
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Paul M Zimmerman
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Anne J McNeil
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States; Macromolecular Science and Engineering Program, University of Michigan, Ann Arbor, Michigan 48109-2800, United States
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3
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Dau H, Jones GR, Tsogtgerel E, Nguyen D, Keyes A, Liu YS, Rauf H, Ordonez E, Puchelle V, Basbug Alhan H, Zhao C, Harth E. Linear Block Copolymer Synthesis. Chem Rev 2022; 122:14471-14553. [PMID: 35960550 DOI: 10.1021/acs.chemrev.2c00189] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Block copolymers form the basis of the most ubiquitous materials such as thermoplastic elastomers, bridge interphases in polymer blends, and are fundamental for the development of high-performance materials. The driving force to further advance these materials is the accessibility of block copolymers, which have a wide variety in composition, functional group content, and precision of their structure. To advance and broaden the application of block copolymers will depend on the nature of combined segmented blocks, guided through the combination of polymerization techniques to reach a high versatility in block copolymer architecture and function. This review provides the most comprehensive overview of techniques to prepare linear block copolymers and is intended to serve as a guideline on how polymerization techniques can work together to result in desired block combinations. As the review will give an account of the relevant procedures and access areas, the sections will include orthogonal approaches or sequentially combined polymerization techniques, which increases the synthetic options for these materials.
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Affiliation(s)
- Huong Dau
- Department of Chemistry, University of Houston, Center for Excellence in Chemistry, CEPC, Houston, Texas 77004, United States
| | - Glen R Jones
- Department of Chemistry, University of Houston, Center for Excellence in Chemistry, CEPC, Houston, Texas 77004, United States
| | - Enkhjargal Tsogtgerel
- Department of Chemistry, University of Houston, Center for Excellence in Chemistry, CEPC, Houston, Texas 77004, United States
| | - Dung Nguyen
- Department of Chemistry, University of Houston, Center for Excellence in Chemistry, CEPC, Houston, Texas 77004, United States
| | - Anthony Keyes
- Department of Chemistry, University of Houston, Center for Excellence in Chemistry, CEPC, Houston, Texas 77004, United States
| | - Yu-Sheng Liu
- Department of Chemistry, University of Houston, Center for Excellence in Chemistry, CEPC, Houston, Texas 77004, United States
| | - Hasaan Rauf
- Department of Chemistry, University of Houston, Center for Excellence in Chemistry, CEPC, Houston, Texas 77004, United States
| | - Estela Ordonez
- Department of Chemistry, University of Houston, Center for Excellence in Chemistry, CEPC, Houston, Texas 77004, United States
| | - Valentin Puchelle
- Department of Chemistry, University of Houston, Center for Excellence in Chemistry, CEPC, Houston, Texas 77004, United States
| | - Hatice Basbug Alhan
- Department of Chemistry, University of Houston, Center for Excellence in Chemistry, CEPC, Houston, Texas 77004, United States
| | - Chenying Zhao
- Department of Chemistry, University of Houston, Center for Excellence in Chemistry, CEPC, Houston, Texas 77004, United States
| | - Eva Harth
- Department of Chemistry, University of Houston, Center for Excellence in Chemistry, CEPC, Houston, Texas 77004, United States
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4
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Ye S, Lotocki V, Xu H, Seferos DS. Group 16 conjugated polymers based on furan, thiophene, selenophene, and tellurophene. Chem Soc Rev 2022; 51:6442-6474. [PMID: 35843215 DOI: 10.1039/d2cs00139j] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Five-membered aromatic rings containing Group 16 elements (O, S, Se, and Te), also referred as chalcogenophenes, are ubiquitous building blocks for π-conjugated polymers (CPs). Among these, polythiophenes have been established as a model system to study the interplay between molecular structure, solid-state organization, and electronic performance. The judicious substitution of alternative heteroatoms into polythiophenes is a promising strategy for tuning their properties and improving the performance of derived organic electronic devices, thus leading to the recent abundance of CPs containing furan, selenophene, and tellurophene. In this review, we first discuss the current status of Kumada, Negishi, Murahashi, Suzuki-Miyaura, and direct arylation polymerizations, representing the best routes to access well-defined chalcogenophene-containing homopolymers and copolymers. The self-assembly, optical, solid-state, and electronic properties of these polymers and their influence on device performance are then summarized. In addition, we highlight post-polymerization modifications as effective methods to transform polychalcogenophene backbones or side chains in ways that are unobtainable by direct polymerization. Finally, the major challenges and future outlook in this field are presented.
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Affiliation(s)
- Shuyang Ye
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada.
| | - Victor Lotocki
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada.
| | - Hao Xu
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada.
| | - Dwight S Seferos
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada. .,Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
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5
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Woods EF, Berl AJ, Kantt LP, Eckdahl CT, Wasielewski MR, Haines BE, Kalow JA. Light Directs Monomer Coordination in Catalyst-Free Grignard Photopolymerization. J Am Chem Soc 2021; 143:18755-18765. [PMID: 34699721 DOI: 10.1021/jacs.1c09595] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
π-Conjugated polymers can serve as active layers in flexible and lightweight electronics and are conventionally synthesized by transition-metal-mediated polycondensation at elevated temperatures. We recently reported a photopolymerization of electron-deficient heteroaryl Grignard monomers that enables the catalyst-free synthesis of n-type π-conjugated polymers. Herein, we describe an experimental and computational investigation into the mechanism of this photopolymerization. Spectroscopic studies performed in situ and after quenching reveal that the propagating chain is a radical anion with halide end groups. DFT calculations for model oligomers suggest a Mg-templated SRN1-type coupling, in which Grignard monomer coordination to the radical anion chain avoids the formation of free sp2 radicals and allows C-C bond formation with very low barriers. We find that light plays an unusual role in the reaction, photoexciting the radical anion chain to shift electron density to the termini and thus enabling productive monomer binding.
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Affiliation(s)
- Eliot F Woods
- Department of Chemistry, Northwestern University, 2145 Sheridan Rd, Evanston, Illinois 60208, United States
| | - Alexandra J Berl
- Department of Chemistry, Northwestern University, 2145 Sheridan Rd, Evanston, Illinois 60208, United States
| | - Leanna P Kantt
- Department of Chemistry, Northwestern University, 2145 Sheridan Rd, Evanston, Illinois 60208, United States
| | - Christopher T Eckdahl
- Department of Chemistry, Northwestern University, 2145 Sheridan Rd, Evanston, Illinois 60208, United States
| | - Michael R Wasielewski
- Department of Chemistry, Northwestern University, 2145 Sheridan Rd, Evanston, Illinois 60208, United States
| | - Brandon E Haines
- Department of Chemistry, Westmont College, 955 La Paz Rd, Santa Barbara, California 93108, United States
| | - Julia A Kalow
- Department of Chemistry, Northwestern University, 2145 Sheridan Rd, Evanston, Illinois 60208, United States
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6
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Cooper AK, Greaves ME, Donohoe W, Burton PM, Ronson TO, Kennedy AR, Nelson DJ. Inhibition of (dppf)nickel-catalysed Suzuki-Miyaura cross-coupling reactions by α-halo-N-heterocycles. Chem Sci 2021; 12:14074-14082. [PMID: 34760191 PMCID: PMC8565371 DOI: 10.1039/d1sc04582b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 10/10/2021] [Indexed: 12/13/2022] Open
Abstract
A nickel/dppf catalyst system was found to successfully achieve the Suzuki-Miyaura cross-coupling reactions of 3- and 4-chloropyridine and of 6-chloroquinoline but not of 2-chloropyridine or of other α-halo-N-heterocycles. Further investigations revealed that chloropyridines undergo rapid oxidative addition to [Ni(COD)(dppf)] but that α-halo-N-heterocycles lead to the formation of stable dimeric nickel species that are catalytically inactive in Suzuki-Miyaura cross-coupling reactions. However, the corresponding Kumada-Tamao-Corriu reactions all proceed readily, which is attributed to more rapid transmetalation of Grignard reagents.
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Affiliation(s)
- Alasdair K Cooper
- WestCHEM Department of Pure and Applied Chemistry, University of Strathclyde 295 Cathedral Street Glasgow G1 1XL Scotland UK
| | - Megan E Greaves
- WestCHEM Department of Pure and Applied Chemistry, University of Strathclyde 295 Cathedral Street Glasgow G1 1XL Scotland UK
- Chemical Development, Pharmaceutical Technology and Development, Operations, AstraZeneca Macclesfield SK10 2NA UK
| | - William Donohoe
- WestCHEM Department of Pure and Applied Chemistry, University of Strathclyde 295 Cathedral Street Glasgow G1 1XL Scotland UK
| | - Paul M Burton
- Syngenta, Jealott's Hill International Research Centre Bracknell Berkshire RG426EY UK
| | - Thomas O Ronson
- Chemical Development, Pharmaceutical Technology and Development, Operations, AstraZeneca Macclesfield SK10 2NA UK
| | - Alan R Kennedy
- WestCHEM Department of Pure and Applied Chemistry, University of Strathclyde 295 Cathedral Street Glasgow G1 1XL Scotland UK
| | - David J Nelson
- WestCHEM Department of Pure and Applied Chemistry, University of Strathclyde 295 Cathedral Street Glasgow G1 1XL Scotland UK
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7
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Pollit AA, Lough AJ, Seferos DS. Examining the Spin State and Redox Chemistry of Ni(Diimine) Catalysts during the Synthesis of π‐Conjugated Polymers. MACROMOL CHEM PHYS 2020. [DOI: 10.1002/macp.202000321] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Adam A. Pollit
- Department of Chemistry University of Toronto 80 St. George Street Toronto ON M5S 3H6 Canada
| | - Alan J. Lough
- Department of Chemistry University of Toronto 80 St. George Street Toronto ON M5S 3H6 Canada
| | - Dwight S. Seferos
- Department of Chemistry University of Toronto 80 St. George Street Toronto ON M5S 3H6 Canada
- University of Toronto 200 College Street Toronto ON M5S 3E5 Canada
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8
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Vitek AK, Jugovic TME, Zimmerman PM. Revealing the Strong Relationships between Ligand Conformers and Activation Barriers: A Case Study of Bisphosphine Reductive Elimination. ACS Catal 2020. [DOI: 10.1021/acscatal.0c00618] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Andrew K. Vitek
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Timothy M. E. Jugovic
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Paul M. Zimmerman
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
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9
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Jarrett-Wilkins CN, Pollit AA, Seferos DS. Polymerization Catalysts Take a Walk on the Wild Side. TRENDS IN CHEMISTRY 2020. [DOI: 10.1016/j.trechm.2020.03.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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10
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Cooper AK, Leonard DK, Bajo S, Burton PM, Nelson DJ. Aldehydes and ketones influence reactivity and selectivity in nickel-catalysed Suzuki-Miyaura reactions. Chem Sci 2020; 11:1905-1911. [PMID: 34123283 PMCID: PMC8148322 DOI: 10.1039/c9sc05444h] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The energetically-favorable coordination of aldehydes and ketones - but not esters or amides - to Ni0 during Suzuki-Miyaura reactions can lead either to exquisite selectivity and enhanced reactivity, or to inhibition of the reaction. Aryl halides where the C-X bond is connected to the same π-system as an aldehyde or ketone undergo unexpectedly rapid oxidative addition to [Ni(COD)(dppf)] (1), and are selectively cross-coupled during competition reactions. When aldehydes and ketones are present in the form of exogenous additives, the cross-coupling reaction is inhibited to an extent that depends on the strength of the coordination of the pendant carbonyl group to Ni0. This work advances our understanding of how common functional groups interact with Ni0 catalysts and how these interactions affect workhorse catalytic reactions in academia and industry.
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Affiliation(s)
- Alasdair K Cooper
- WestCHEM Department of Pure and Applied Chemistry, University of Strathclyde 295 Cathedral Street Glasgow G1 1XL Scotland UK
| | - David K Leonard
- WestCHEM Department of Pure and Applied Chemistry, University of Strathclyde 295 Cathedral Street Glasgow G1 1XL Scotland UK
| | - Sonia Bajo
- WestCHEM Department of Pure and Applied Chemistry, University of Strathclyde 295 Cathedral Street Glasgow G1 1XL Scotland UK
| | - Paul M Burton
- Syngenta, Jealott's Hill International Research Centre Bracknell Berkshire RG42 6EY UK
| | - David J Nelson
- WestCHEM Department of Pure and Applied Chemistry, University of Strathclyde 295 Cathedral Street Glasgow G1 1XL Scotland UK
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11
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Pollit AA, Ye S, Seferos DS. Elucidating the Role of Catalyst Steric and Electronic Effects in Controlling the Synthesis of π-Conjugated Polymers. Macromolecules 2020. [DOI: 10.1021/acs.macromol.9b02098] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Adam A. Pollit
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Shuyang Ye
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Dwight S. Seferos
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
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12
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Rama RJ, Martín MT, Peloso R, Nicasio MC. Low-coordinate M(0) complexes of group 10 stabilized by phosphorus(III) ligands and N-heterocyclic carbenes. ADVANCES IN ORGANOMETALLIC CHEMISTRY 2020. [DOI: 10.1016/bs.adomc.2020.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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13
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Affiliation(s)
- Dylan J. Walsh
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Michael G. Hyatt
- Department of Chemistry, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Susannah A. Miller
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Damien Guironnet
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
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14
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Desnoyer AN, He W, Behyan S, Chiu W, Love JA, Kennepohl P. The Importance of Ligand-Induced Backdonation in the Stabilization of Square Planar d 10 Nickel π-Complexes. Chemistry 2019; 25:5259-5268. [PMID: 30693581 DOI: 10.1002/chem.201805987] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Indexed: 01/06/2023]
Abstract
The electronic nature of Ni π-complexes is underexplored even though these complexes have been widely postulated as intermediates in organometallic chemistry. Herein, the geometric and electronic structure of a series of nickel π-complexes, Ni(dtbpe)(X) (dtbpe=1,2-bis(di-tert-butyl)phosphinoethane; X=alkene or carbonyl containing π-ligands), is probed using a combination of 31 P NMR, Ni K-edge XAS, Ni Kβ XES, and DFT calculations. These complexes are best described as square planar d10 complexes with π-backbonding acting as the dominant contributor to M-L bonding to the π-ligand. The degree of backbonding correlates with 2 JPP from NMR and the energy of the Ni 1s→4pz pre-edge in the Ni K-edge XAS data, and is determined by the energy of the π*ip ligand acceptor orbital. Thus, unactivated olefinic ligands tend to be poor π-acids whereas ketones, aldehydes, and esters allow for greater backbonding. However, backbonding is still significant even in cases in which metal contributions are minor. In such cases, backbonding is dominated by charge donation from the diphosphine, which allows for strong backdonation, although the metal centre retains a formal d10 electronic configuration. This ligand-induced backbonding can be formally described as a 3-centre-4-electron (3c-4e) interaction, in which the nickel centre mediates charge transfer from the phosphine σ-donors to the π*ip ligand acceptor orbital. The implications of this bonding motif are described with respect to both structure and reactivity.
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Affiliation(s)
- Addison N Desnoyer
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, V6T 1Z1, Vancouver, BC, Canada
| | - Weiying He
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, V6T 1Z1, Vancouver, BC, Canada
| | - Shirin Behyan
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, V6T 1Z1, Vancouver, BC, Canada
| | - Weiling Chiu
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, V6T 1Z1, Vancouver, BC, Canada
| | - Jennifer A Love
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, V6T 1Z1, Vancouver, BC, Canada
| | - Pierre Kennepohl
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, V6T 1Z1, Vancouver, BC, Canada
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15
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Grisorio R, Suranna GP. Catalyst-transfer polymerization of arylamines by the Buchwald–Hartwig cross-coupling. Polym Chem 2019. [DOI: 10.1039/c8py01646a] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The control over the polymerization course of arylamines by the Buchwald–Hartwig reaction was achieved by the introduction of suitable functional groups onto the AB-type monomer.
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Affiliation(s)
- Roberto Grisorio
- DICATECh – Dipartimento di Ingegneria Civile
- Ambientale
- del Territorio
- Edile e di Chimica
- Politecnico di Bari
| | - Gian Paolo Suranna
- DICATECh – Dipartimento di Ingegneria Civile
- Ambientale
- del Territorio
- Edile e di Chimica
- Politecnico di Bari
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16
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He W, Kennepohl P. Direct experimental evaluation of ligand-induced backbonding in nickel metallacyclic complexes. Faraday Discuss 2019; 220:133-143. [PMID: 31544197 DOI: 10.1039/c9fd00041k] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The details of ligand-induced backbonding in nickel diphosphine π complexes are explored using nickel L-edge (3d←2p) X-ray absorption spectroscopy as a means of quantifying the degree of backbonding derived from direct Ni 3d donation into the π ligand. It is observed that backbonding into weakly π acidic ligands such as alkenes and arenes is dominated by contributions from the diphosphine ligand via σ-donation, leading to activated metallacycles with a Ni(0) d10 metal centre. With more strongly π acidic ligands, however, metal contributions to backbonding increase substantially leading to a more electron-deficient metal centre that is best described as having a Ni(i) spectroscopic oxidation state.
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Affiliation(s)
- Weiying He
- The University of British Columbia, Department of Chemistry, 2036 Main Mall, Vancouver, British Columbia, Canada.
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