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van der Zee LJC, Hofman J, van Gaalen JM, Slootweg JC. Mechanistic studies on single-electron transfer in frustrated Lewis pairs and its application to main-group chemistry. Chem Soc Rev 2024; 53:4862-4876. [PMID: 38623621 PMCID: PMC11104263 DOI: 10.1039/d4cs00185k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Indexed: 04/17/2024]
Abstract
Advances in the field of frustrated Lewis pair (FLP) chemistry have led to the discovery of radical pairs, obtained by a single-electron transfer (SET) from the Lewis base to the Lewis acid. Radical pairs are intriguing for their potential to enable cooperative activation of challenging substrates (e.g., CH4, N2) in a homolytic fashion, as well as the exploration of novel radical reactions. In this review, we will cover the two known mechanisms of SET in FLPs-thermal and photoinduced-along with methods (i.e., CV, DFT, UV-vis) to predict the mechanism and to characterise the involved electron donors and acceptors. Furthermore, the available techniques (i.e., EPR, UV-vis, transient absorption spectroscopy) for studying the corresponding radical pairs will be discussed. Initially, two model systems (PMes3/CPh3+ and PMes3/B(C6F5)3) will be reviewed to highlight the difference between a thermal and a photoinduced SET mechanism. Additionally, three cases are analysed to provide further tools and insights into characterizing electron donors and acceptors, and the associated radical pairs. Firstly, a thermal SET process between LiHMDS and [TEMPO][BF4] is discussed. Next, the influence of Lewis acid complexation on the electron acceptor will be highlighted to facilitate a SET between (pBrPh)3N and TCNQ. Finally, an analysis of sulfonium salts as electron acceptors will demonstrate how to manage systems with rapidly decomposing radical species. This framework equips the reader with an expanded array of tools for both predicting and characterizing SET events within FLP chemistry, thereby enabling its extension and application to the broader domain of main-group (photo)redox chemistry.
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Affiliation(s)
- Lars J C van der Zee
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, PO box 94157, 1090 GD Amsterdam, The Netherlands.
| | - Jelle Hofman
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, PO box 94157, 1090 GD Amsterdam, The Netherlands.
| | - Joost M van Gaalen
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, PO box 94157, 1090 GD Amsterdam, The Netherlands.
| | - J Chris Slootweg
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, PO box 94157, 1090 GD Amsterdam, The Netherlands.
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2
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Steffenfauseweh H, Vishnevskiy YV, Neumann B, Stammler HG, de Bruin B, Ghadwal RS. N-Heterocyclic Carbene Analogues of Wittig Hydrocarbon. Chemistry 2024; 30:e202400879. [PMID: 38437163 DOI: 10.1002/chem.202400879] [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: 03/03/2024] [Accepted: 03/04/2024] [Indexed: 03/06/2024]
Abstract
N-Heterocyclic carbene (NHC) analogues of Wittig hydrocarbon, [(NHC)(Stil)(NHC)] (3a-c) (NHC = SIPr (1a) = C[N(Dipp)CH2]2, Dipp = 2,6-iPr2C6H3; IPr (1b) = C[N(Dipp)CH]2; Me-IPr (1c) = C[N(Dipp)CMe]2 and Stil = C6H4CHCHC6H4) have been reported as crystalline solids. 3a-c are prepared by two-electron reductions of the corresponding bis-1,3-imidazoli(ni)um bromides [(NHC)(Stil)NHC)](Br)2 (2a-c) with KC8 in >94 % yields. 2a-c are accessible by the nickel catalyzed direct C-C coupling of NHCs (1a-c) with (E)-4,4'-dibromostilbene. One-electron oxidation of 3a,b yields the corresponding radical cations [(NHC)(Stil)NHC)]B(C6F5)4 4a,b. All compounds have been characterized by UV-Vis/NMR/EPR spectroscopy as well as 2a, 3a, and 3b by single crystal X-ray diffraction. The electronic structures of representative systems have been analyzed by quantum chemical calculations.
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Affiliation(s)
- Henric Steffenfauseweh
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| | - Yury V Vishnevskiy
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| | - Beate Neumann
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| | - Hans-Georg Stammler
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| | - Bas de Bruin
- University of Amsterdam (UvA), Faculty of Science, Van 't Hoff Institute for Molecular Sciences (HIMS), Homogeneous and Supramolecular Catalysis Group, Science Park 904, 1098 XH, Amsterdam, The Netherlands
| | - Rajendra S Ghadwal
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
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3
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Wu M, Saya JM, Han P, Walia R, Pradhan B, Honing M, Ranjan P, Orru RVA. Shining light on tryptamine-derived isocyanides: access to constrained spirocylic scaffolds. Chem Sci 2024; 15:6867-6873. [PMID: 38725510 PMCID: PMC11077512 DOI: 10.1039/d3sc06304f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Accepted: 04/04/2024] [Indexed: 05/12/2024] Open
Abstract
Dearomatization of indoles through a charge transfer complex constitutes a powerful tool for synthesizing three-dimensional constrained structures. However, the implementation of this strategy for the dearomatization of tryptamine-derived isocyanides to generate spirocyclic scaffolds remains underdeveloped. In this work, we have demonstrated the ability of tryptamine-derived isocyanides to form aggregates at higher concentration, enabling a single electron transfer step to generate carbon-based-radical intermediates. Optical, HRMS and computational studies have elucidated key aspects associated with the photophysical properties of tryptamine-derived isocyanides. The developed protocol is operationally simple, robust and demonstrates a novel approach to generate conformationally constrained spirocyclic scaffolds, compounds with high demand in various fields, including drug discovery.
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Affiliation(s)
- Minghui Wu
- Aachen Maastricht Institute for Biobased Materials (AMIBM), Maastricht University Urmonderbaan 22 6167 RD Geleen The Netherlands
| | - Jordy M Saya
- Aachen Maastricht Institute for Biobased Materials (AMIBM), Maastricht University Urmonderbaan 22 6167 RD Geleen The Netherlands
| | - Peiliang Han
- Maastricht MultiModal Molecular Imaging Institute (M4i), Division of Imaging Mass Spectrometry, Maastricht University Universiteitssingel 50 6229 ER Maastricht The Netherlands
| | - Rajat Walia
- Department of Chemistry, City University of Hong Kong Tat Chee Avenue Kowloon Hong Kong SAR
| | - Bapi Pradhan
- Molecular Imaging and Photonics, Department of Chemistry KU Leuven, Celestijnenlaan 200F 3001 Leuven Belgium
| | - Maarten Honing
- Maastricht MultiModal Molecular Imaging Institute (M4i), Division of Imaging Mass Spectrometry, Maastricht University Universiteitssingel 50 6229 ER Maastricht The Netherlands
| | - Prabhat Ranjan
- Aachen Maastricht Institute for Biobased Materials (AMIBM), Maastricht University Urmonderbaan 22 6167 RD Geleen The Netherlands
| | - Romano V A Orru
- Aachen Maastricht Institute for Biobased Materials (AMIBM), Maastricht University Urmonderbaan 22 6167 RD Geleen The Netherlands
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4
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Kong S, Yang L, Sun Q, Wang T, Pei R, Zhao Y, Wang W, Zhao Y, Cui H, Gu X, Wang X. Metal-Free Catalytic Formation of a Donor-Acceptor-Donor Molecule and Its Lewis Acid-Adduct Singlet Diradical with High-Efficient NIR-II Photothermal Conversion. Angew Chem Int Ed Engl 2024; 63:e202400913. [PMID: 38441914 DOI: 10.1002/anie.202400913] [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: 01/15/2024] [Indexed: 04/05/2024]
Abstract
We have synthesized a quinone-incorporated bistriarylamine donor-acceptor-donor (D-A-D) semiconductor 1 by B(C6F5)3 (BCF) catalyzed C-H/C-H cross coupling via radical ion pair intermediates. Coordination of Lewis acids BCF and Al(ORF)3 (RF=C(CF3)3) to the semiconductor 1 afforded diradical zwitterions 2 and 3 by integer electron transfer. Upon binding to Lewis acids, the LUMO energy of 1 is significantly lowered and the band gap of the semiconductor is significantly narrowed from 1.93 eV (1) to 1.01 eV (2) and 1.06 eV (3). 2 and 3 are rare near-infrared (NIR) diradical dyes with broad absorption both centered around 1500 nm. By introducing a photo BCF generator, 2 can be generated by light-dependent control. Furthermore, the integer electron transfer process can also be reversibly regulated via the addition of CH3CN. In addition, the temperature of 2 sharply increased and reached as high as 110 °C in 10 s upon the irradiation of near-infrared-II (NIR-II) laser (1064 nm, 0.7 W cm-2), exhibiting a fast response to laser. It displays excellent photothermal stability with a photothermal (PT) conversion efficiency of 62.26 % and high-quality PT imaging.
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Affiliation(s)
- Shanshan Kong
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, China
| | - Liming Yang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Quanchun Sun
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, China
| | - Tao Wang
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, China
| | - Runbo Pei
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, China
| | - Yue Zhao
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, China
| | - Wenqing Wang
- College of Chemistry and Materials Science, Key Laboratory of Functional Molecular Solids, Ministry of Education, Anhui Laboratory of Moleculer-Based Materials, Anhui Normal University, Wuhu, 241002, China
| | - Yu Zhao
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, China
| | - Haiyan Cui
- Jiangsu Key Laboratory of Pesticide Science, College of Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Xinggui Gu
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Xinping Wang
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, China
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Science, Shanghai, 200032, China
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5
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Muralidharan AV, Frenette BL, Wicke J, Omaña AA, Ferguson MJ, Rivard E. Frustrated Lewis pair adducts of alkynyl-capped tetrelenes. Dalton Trans 2024; 53:7206-7212. [PMID: 38584458 DOI: 10.1039/d4dt00795f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
The frustrated Lewis pair (FLP) adducts PB{ECl2} (PB = iPr2P(C6H4)BCy2; Cy = cyclohexyl; E = Si, Ge) were used to access a bis(alkynyl)-functionalized silylene and a germylene; the goal behind preparing these species was to obtain new unsaturated main group polymers [E(CCSiMe3)2]n upon heating. While the silylene adduct PB{Si(CCSiMe3)2} was stable up to 150 °C, the heavier element congener PB{Ge(CCSiMe3)2} underwent a complicated rearrangement process accompanied by Cy-group migration and Ge(II)-alkyne coordination. Density functional theory computations were performed to understand the mechanistic pathway for the unusual rearrangement of PB{Ge(CCSiMe3)2}.
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Affiliation(s)
- Abhishek V Muralidharan
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Edmonton, Alberta, T6G 2G2, Canada.
| | - Brandon L Frenette
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Edmonton, Alberta, T6G 2G2, Canada.
| | - Julius Wicke
- Institut für Anorganische und Analytische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Straße 7, D-60438, Frankfurt am Main, Germany
| | - Alvaro A Omaña
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Edmonton, Alberta, T6G 2G2, Canada.
| | - Michael J Ferguson
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Edmonton, Alberta, T6G 2G2, Canada.
| | - Eric Rivard
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Edmonton, Alberta, T6G 2G2, Canada.
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Li M, Deng YH, Chang Q, Li J, Wang C, Wang L, Sun TY. Photoinduced Site-Selective Aryl C-H Borylation with Electron-Donor-Acceptor Complex Derived from B 2Pin 2 and Isoquinoline. Molecules 2024; 29:1783. [PMID: 38675603 PMCID: PMC11052414 DOI: 10.3390/molecules29081783] [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: 03/26/2024] [Revised: 04/08/2024] [Accepted: 04/08/2024] [Indexed: 04/28/2024] Open
Abstract
Due to boron's metalloid properties, aromatic boron reagents are prevalent synthetic intermediates. The direct borylation of aryl C-H bonds for producing aromatic boron compounds offers an appealing, one-step solution. Despite significant advances in this field, achieving regioselective aryl C-H bond borylation using simple and readily available starting materials still remains a challenge. In this work, we attempted to enhance the reactivity of the electron-donor-acceptor (EDA) complex by selecting different bases to replace the organic base (NEt3) used in our previous research. To our delight, when using NH4HCO3 as the base, we have achieved a mild visible-light-mediated aromatic C-H bond borylation reaction with exceptional regioselectivity (rr > 40:1 to single isomers). Compared with our previous borylation methodologies, this protocol provides a more efficient and broader scope for aryl C-H bond borylation through the use of N-Bromosuccinimide. The protocol's good functional-group tolerance and excellent regioselectivity enable the functionalization of a variety of biologically relevant compounds and novel cascade transformations. Mechanistic experiments and theoretical calculations conducted in this study have indicated that, for certain arenes, the aryl C-H bond borylation might proceed through a new reaction mechanism, which involves the formation of a novel transient EDA complex.
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Affiliation(s)
- Manhong Li
- Key Lab of Computational Chemistry and Drug Design, State Key Laboratory of Chemical Oncogenomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China; (M.L.); (Y.-H.D.); (C.W.)
- School of Pharmaceutical Sciences (Shenzhen), Sun Yat-sen University, No. 66, Gongchang Road, Shenzhen 518107, China;
- Institute of Molecular Chemical Biology, Shenzhen Bay Laboratory, Shenzhen 518132, China
- Department of Pharmacy and Pharmaceutical Sciences, Faculty of Science, National University of Singapore, Block S4A, Level 3, 18 Science Drive 4, Singapore 117543, Singapore
| | - Yi-Hui Deng
- Key Lab of Computational Chemistry and Drug Design, State Key Laboratory of Chemical Oncogenomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China; (M.L.); (Y.-H.D.); (C.W.)
| | - Qianqian Chang
- School of Pharmaceutical Sciences (Shenzhen), Sun Yat-sen University, No. 66, Gongchang Road, Shenzhen 518107, China;
| | - Jinyuan Li
- Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Lu, Shanghai 200032, China;
| | - Chao Wang
- Key Lab of Computational Chemistry and Drug Design, State Key Laboratory of Chemical Oncogenomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China; (M.L.); (Y.-H.D.); (C.W.)
| | - Leifeng Wang
- School of Pharmaceutical Sciences (Shenzhen), Sun Yat-sen University, No. 66, Gongchang Road, Shenzhen 518107, China;
| | - Tian-Yu Sun
- Key Lab of Computational Chemistry and Drug Design, State Key Laboratory of Chemical Oncogenomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China; (M.L.); (Y.-H.D.); (C.W.)
- Institute of Molecular Chemical Biology, Shenzhen Bay Laboratory, Shenzhen 518132, China
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7
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Ebeler F, Neumann B, Stammler HG, Ghadwal RS. Divergent Reactivity of a Cyclic Bis-Hydridostannylene: A Masked Sn(I) Diradicaloid. Chemistry 2024; 30:e202400382. [PMID: 38294490 DOI: 10.1002/chem.202400382] [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: 01/29/2024] [Revised: 01/31/2024] [Accepted: 01/31/2024] [Indexed: 02/01/2024]
Abstract
Herein, reactivity studies of a cyclic bis-hydridostannylene [(ADC)SnH]2 (1-H2) (ADC=PhC{(NDipp)C}2; Dipp=2,6-iPr2C6H3) with various unsaturated organic substrates are reported. Reactions of terminal alkynes (RC≡CH) with 1-H2 afford mixed acetylide-vinyl-functionalized bis-stannylenes via dehydrogenation and hydrostannylation. Treatment of 1-H2 with PhC≡CCH3 gives a unique distannabarrelene via dehydrogenative C(sp3)-H stannylation and hydrostannylation of the C≡CCH3 moiety. 1-H2 undergoes dehydrogenative [2+2]-cycloaddition reactions with diphenylacetylene, azobenzene, acetone, benzophenone, and benzaldehyde to form the 1,4-distannabarrelene derivatives. The elimination of H2 in these reactions suggests the masked-diradical property of 1-H2. In fact, these [2+2]-cycloaddition products are also accessible on treatments of the Sn(I) diradicaloid [(ADC)Sn]2 (1) with appropriate reagents. All compounds have been characterized by multinuclear NMR spectroscopy and single crystal X-ray diffraction. Moreover, the catalytic activity of 1-H2 has been shown for the hydroboration of unsaturated substrates.
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Affiliation(s)
- Falk Ebeler
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| | - Beate Neumann
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| | - Hans-Georg Stammler
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| | - Rajendra S Ghadwal
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
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8
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Morales A, Gonçalves C, Sournia-Saquet A, Vendier L, Lledós A, Baslé O, Bontemps S. Single electron reduction of NHC-CO 2-borane compounds. Chem Sci 2024; 15:3165-3173. [PMID: 38425525 PMCID: PMC10901481 DOI: 10.1039/d3sc06325a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Accepted: 01/18/2024] [Indexed: 03/02/2024] Open
Abstract
The carbon dioxide radical anion [CO2˙-] is a highly reactive species of fundamental and synthetic interest. However, the direct one-electron reduction of CO2 to generate [CO2˙-] occurs at very negative reduction potentials, which is often a limiting factor for applications. Here, we show that NHC-CO2-BR3 species - generated from the Frustrated Lewis Pair (FLP)-type activation of CO2 by N-heterocyclic carbenes (NHCs) and boranes (BR3) - undergo single electron reduction at a less negative potential than free CO2. A net gain of more than one volt was notably measured with a CAAC-CO2-B(C6F5)3 adduct, which was chemically reduced to afford [CAAC-CO2-B(C6F5)3˙-]. This room temperature stable radical anion was characterized by EPR spectroscopy and by single-crystal X-ray diffraction analysis. Of particular interest, DFT calculations showed that, thanks to the electron withdrawing properties of the Lewis acid, significant unpaired spin density is localised on the carbon atom of the CO2 moiety. Finally, these species were shown to exhibit analogous reactivity to the carbon dioxide radical anion [CO2˙-] toward DMPO. This work demonstrates the advantage provided by FLP systems in the generation and stabilization of [CO2˙-]-like species.
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Affiliation(s)
- Agustín Morales
- LCC-CNRS, Université de Toulouse, CNRS, 205 route de Narbonne 31077 Toulouse Cedex 04 France
- Departament de Química, Universitat Autonoma de Barcelona 08193 Cerdanyola del Valles Catalonia Spain
| | - Caroline Gonçalves
- LCC-CNRS, Université de Toulouse, CNRS, 205 route de Narbonne 31077 Toulouse Cedex 04 France
| | - Alix Sournia-Saquet
- LCC-CNRS, Université de Toulouse, CNRS, 205 route de Narbonne 31077 Toulouse Cedex 04 France
| | - Laure Vendier
- LCC-CNRS, Université de Toulouse, CNRS, 205 route de Narbonne 31077 Toulouse Cedex 04 France
| | - Agustí Lledós
- Departament de Química, Universitat Autonoma de Barcelona 08193 Cerdanyola del Valles Catalonia Spain
| | - Olivier Baslé
- LCC-CNRS, Université de Toulouse, CNRS, 205 route de Narbonne 31077 Toulouse Cedex 04 France
| | - Sébastien Bontemps
- LCC-CNRS, Université de Toulouse, CNRS, 205 route de Narbonne 31077 Toulouse Cedex 04 France
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9
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Lye K, Young RD. A review of frustrated Lewis pair enabled monoselective C-F bond activation. Chem Sci 2024; 15:2712-2724. [PMID: 38404400 PMCID: PMC10882520 DOI: 10.1039/d3sc06485a] [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: 12/04/2023] [Accepted: 01/07/2024] [Indexed: 02/27/2024] Open
Abstract
Frustrated Lewis pair (FLP) bond activation chemistry has greatly developed over the last two decades since the seminal report of metal-free reversible hydrogen activation. Recently, FLP systems have been utilized to allow monoselective C-F bond activation (at equivalent sites) in polyfluoroalkanes. The problem of 'over-defluorination' in the functionalization of polyfluoroalkanes (where multiple fluoro-positions are uncontrollably functionalized) has been a long-standing chemical problem in fluorocarbon chemistry for over 80 years. FLP mediated monoselective C-F bond activation is complementary to other solutions developed to address 'over-defluorination' and offers several advantages and unique opportunities. This perspective highlights some of these advantages and opportunities and places the development of FLP mediated C-F bond activation into the context of the wider effort to overcome 'over-defluorination'.
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Affiliation(s)
- Kenneth Lye
- Department of Chemistry, National University of Singapore 117543 Singapore
| | - Rowan D Young
- School of Chemistry and Molecular Biosciences, The University of Queensland St Lucia 4072 Australia
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10
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Qu ZW, Zhu H, Grimme S. Reactivity of Frustrated Lewis Pair: Carbocation versus Radical Intermediates. Chemistry 2024; 30:e202303901. [PMID: 38116858 DOI: 10.1002/chem.202303901] [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: 11/23/2023] [Revised: 12/18/2023] [Accepted: 12/19/2023] [Indexed: 12/21/2023]
Abstract
Recent reports of radical formation within frustrated Lewis pairs (FLPs) suggested that single-electron transfer (SET) could play an important role in their chemistry especially for C-C coupling. In sharp contrast, our extensive dispersion-corrected DFT calculations show that although reactive benzhydryl radical along with phosphine radical cation species can be kinetically generated from bulky phosphines and benzhydryl cation, direct P-C hetero-coupling may lead to bulky phosphonium cation as reactive carbocation transfer reagents to styrene substrates, which is kinetically much more favorable than the recently proposed radical C-C coupling between benzhydryl radical and styrene. Similarly, meta-stable radical cation Mes3 P+ ⋅ salt is also kinetically accessible via SET reactions of Mes3 P and B(C6 F5 )3 with 0.5 equivalent of p-O2 C6 Cl4 .
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Affiliation(s)
- Zheng-Wang Qu
- Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstr. 4, 53115, Bonn, Germany
| | - Hui Zhu
- Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstr. 4, 53115, Bonn, Germany
| | - Stefan Grimme
- Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstr. 4, 53115, Bonn, Germany
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11
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Guo Y, Lian X, Zhang H, Zhang X, Chen J, Chen C, Lan X, Shao Y. Systematic Assessment of the Catalytic Reactivity of Frustrated Lewis Pairs in C-H Bond Activation. Molecules 2023; 29:24. [PMID: 38202607 PMCID: PMC10780200 DOI: 10.3390/molecules29010024] [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: 11/23/2023] [Revised: 12/15/2023] [Accepted: 12/18/2023] [Indexed: 01/12/2024] Open
Abstract
Unreactive C-H bond activation is a new horizon for frustrated Lewis pair (FLP) chemistry. This study provides a systematic assessment of the catalytic reactivity of recently reported intra-molecular FLPs on the activation of typical inert C-H bonds, including 1-methylpyrrole, methane, benzyl, propylene, and benzene, in terms of density functional theory (DFT) calculations. The reactivity of FLPs is evaluated according to the calculated reaction thermodynamic and energy barriers of C-H bond activation processes in the framework of concerted C-H activation mechanisms. As for 1-methylpyrrole, 14 types of N-B-based and 15 types of P-B-based FLPs are proposed to be active. Although none of the evaluated FLPs are able to catalyze the C-H activation of methane, benzyl, or propylene, four types of N-B-based FLPs are suggested to be capable of catalyzing the activation of benzene. Moreover, the influence of the strength of Lewis acid (LA) and Lewis base (LB), and the differences between the influences of LA and LB on the catalytic reactivity of FLPs, are also discussed briefly. This systematic assessment of the catalytic activity of FLPs should provide valuable guidelines to aid the development of efficient FLP-based metal-free catalysts for C-H bond activation.
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Affiliation(s)
- Yongjie Guo
- Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds Research and Application, School of Chemistry and Environmental Science, Xiangnan University, Chenzhou 423000, China; (Y.G.); (H.Z.); (J.C.); (C.C.)
| | - Xueqi Lian
- Key Laboratory of Electronic Functional Materials and Devices of Guangdong Province, School of Chemistry and Materials Engineering, Huizhou University, Huizhou 516007, China; (X.L.); (X.Z.)
| | - Hao Zhang
- Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds Research and Application, School of Chemistry and Environmental Science, Xiangnan University, Chenzhou 423000, China; (Y.G.); (H.Z.); (J.C.); (C.C.)
| | - Xueling Zhang
- Key Laboratory of Electronic Functional Materials and Devices of Guangdong Province, School of Chemistry and Materials Engineering, Huizhou University, Huizhou 516007, China; (X.L.); (X.Z.)
| | - Jun Chen
- Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds Research and Application, School of Chemistry and Environmental Science, Xiangnan University, Chenzhou 423000, China; (Y.G.); (H.Z.); (J.C.); (C.C.)
| | - Changzhong Chen
- Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds Research and Application, School of Chemistry and Environmental Science, Xiangnan University, Chenzhou 423000, China; (Y.G.); (H.Z.); (J.C.); (C.C.)
| | - Xiaobing Lan
- Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds Research and Application, School of Chemistry and Environmental Science, Xiangnan University, Chenzhou 423000, China; (Y.G.); (H.Z.); (J.C.); (C.C.)
| | - Youxiang Shao
- Key Laboratory of Electronic Functional Materials and Devices of Guangdong Province, School of Chemistry and Materials Engineering, Huizhou University, Huizhou 516007, China; (X.L.); (X.Z.)
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12
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Helling C, van der Zee LJC, Hofman J, de Zwart FJ, Mathew S, Nieger M, Slootweg JC. Homolytic C-H Bond Activation by Phosphine-Quinone-Based Radical Ion Pairs. Angew Chem Int Ed Engl 2023; 62:e202313397. [PMID: 37831966 DOI: 10.1002/anie.202313397] [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: 09/09/2023] [Revised: 10/04/2023] [Accepted: 10/13/2023] [Indexed: 10/15/2023]
Abstract
Herein, we present the formation of transient radical ion pairs (RIPs) by single-electron transfer (SET) in phosphine-quinone systems and explore their potential for the activation of C-H bonds. PMes3 (Mes=2,4,6-Me3 C6 H2 ) reacts with DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone) with formation of the P-O bonded zwitterionic adduct Mes3 P-DDQ (1), while the reaction with the sterically more crowded PTip3 (Tip=2,4,6-iPr3 C6 H2 ) afforded C-H bond activation product Tip2 P(H)(2-[CMe2 (DDQ)]-4,6-iPr2 -C6 H2 ) (2). UV/Vis and EPR spectroscopic studies showed that the latter reaction proceeds via initial SET, forming RIP [PTip3 ]⋅+ [DDQ]⋅- , and subsequent homolytic C-H bond activation, which was supported by DFT calculations. The isolation of analogous products, Tip2 P(H)(2-[CMe2 {TCQ-B(C6 F5 )3 }]-4,6-iPr2 -C6 H2 ) (4, TCQ=tetrachloro-1,4-benzoquinone) and Tip2 P(H)(2-[CMe2 {oQtBu -B(C6 F5 )3 }]-4,6-iPr2 -C6 H2 ) (8, oQtBu =3,5-di-tert-butyl-1,2-benzoquinone), from reactions of PTip3 with Lewis-acid activated quinones, TCQ-B(C6 F5 )3 and oQtBu -B(C6 F5 )3 , respectively, further supports the proposed radical mechanism. As such, this study presents key mechanistic insights into the homolytic C-H bond activation by the synergistic action of radical ion pairs.
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Affiliation(s)
- Christoph Helling
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, PO Box 94157, 1090, GD Amsterdam, The Netherlands
| | - Lars J C van der Zee
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, PO Box 94157, 1090, GD Amsterdam, The Netherlands
| | - Jelle Hofman
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, PO Box 94157, 1090, GD Amsterdam, The Netherlands
| | - Felix J de Zwart
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, PO Box 94157, 1090, GD Amsterdam, The Netherlands
| | - Simon Mathew
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, PO Box 94157, 1090, GD Amsterdam, The Netherlands
| | - Martin Nieger
- Department of Chemistry, University of Helsinki, A. I. Virtasen aukio 1, P.O. Box 55, FIN-00014, Helsinki, Finland
| | - J Chris Slootweg
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, PO Box 94157, 1090, GD Amsterdam, The Netherlands
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13
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Wang M, Shanmugam M, McInnes EJL, Shaver MP. Light-Induced Polymeric Frustrated Radical Pairs as Building Blocks for Materials and Photocatalysts. J Am Chem Soc 2023; 145:24294-24301. [PMID: 37890166 PMCID: PMC10636756 DOI: 10.1021/jacs.3c09075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Revised: 10/06/2023] [Accepted: 10/11/2023] [Indexed: 10/29/2023]
Abstract
Polymeric frustrated Lewis pairs, or poly(FLP)s, have served to bridge the gap between functional polymer science and main group catalysis, pairing the uniqueness of sterically frustrated Lewis acids and bases with a polymer scaffold to create self-healing gels and recyclable catalysts. However, their utilization in radical chemistry is unprecedented. In this paper, we disclose the synthesis of polymeric frustrated radical pairs, or poly(FRP)s, by in situ photoinduction of FLP moieties, where their Lewis acidic and basic centers are tuned to promote single electron transfer (SET). Through systematic manipulation of the chemical structure, we demonstrate that inclusion of ortho-methyl groups on phosphine monomers is crucial to enable SET. The generation of radicals is evidenced by monitoring the stable polymeric phosphine radical cations via UV/vis and EPR spectroscopy. These new poly(FRP)s enable both catalytic hydrogenation and radical-mediated photocatalytic perfluoroalkylations. These polymeric radical systems open new avenues to design novel functional polymers for catalysis and photoelectrical chemistry.
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Affiliation(s)
- Meng Wang
- Department
of Materials, School of Natural Sciences, University of Manchester, Manchester M13 9PL, U.K.
- Sustainable
Materials Innovation Hub, Henry Royce Institute, University of Manchester, Manchester M13 9PL, U.K.
| | - Muralidharan Shanmugam
- Photon
Science Institute, Department of Chemistry, The University of Manchester, Manchester M13 9PL, U.K.
| | - Eric J. L. McInnes
- Photon
Science Institute, Department of Chemistry, The University of Manchester, Manchester M13 9PL, U.K.
| | - Michael P. Shaver
- Department
of Materials, School of Natural Sciences, University of Manchester, Manchester M13 9PL, U.K.
- Sustainable
Materials Innovation Hub, Henry Royce Institute, University of Manchester, Manchester M13 9PL, U.K.
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14
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Ju M, Lu Z, Novaes LFT, Alvarado JIM, Lin S. Frustrated Radical Pairs in Organic Synthesis. J Am Chem Soc 2023; 145:19478-19489. [PMID: 37656899 PMCID: PMC10625356 DOI: 10.1021/jacs.3c07070] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/03/2023]
Abstract
Frustrated radical pairs (FRPs) describe the phenomenon that two distinct radicals─which would otherwise annihilate each other to form a closed-shell covalent adduct─can coexist in solution, owing to steric repulsion or weak bonding association. FRPs are typically formed via spontaneous single-electron transfer between two sterically encumbered precursors─an oxidant and a reductant─under ambient conditions. The two components of a FRP exhibit orthogonal chemical properties and can often act in cooperativity to achieve interesting radical reactivities. Initially observed in the study of traditional frustrated Lewis pairs, FRPs have recently been shown to be capable of homolytically activating various chemical bonds. In this Perspective, we will discuss the discovery of FRPs, their fundamental reactivity in chemical bond activation, and recent developments of their use in synthetic organic chemistry, including in C-H bond functionalization. We anticipate that FRPs will provide new reaction strategies for solving challenging problems in modern organic synthesis.
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Affiliation(s)
| | | | - Luiz F. T. Novaes
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | | | - Song Lin
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
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