1
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Song Y, Song H, Choi Y, Seo J, Lee E. Synthesis of sterically congested unsymmetrical 1,2-dicarbonyl radicals through a stepwise approach. Chem Commun (Camb) 2024; 60:8043-8046. [PMID: 38989550 DOI: 10.1039/d4cc02092h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/12/2024]
Abstract
A simplified and stepwise synthetic method for producing sterically congested unsymmetrical 1,2-dicarbonyl radicals was successfully demonstrated including detailed characterization of each radical cation. Using this approach, an aryl- and N-heterocyclic carbene-substituted 1,2-dicarbonyl radical in its neutral form is generated, revealing the stabilizing role of N-heterocyclic carbenes.
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Affiliation(s)
- Yuna Song
- Department of Chemistry, Seoul National University (SNU), Seoul, 08826, Republic of Korea.
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Hayoung Song
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Yunseop Choi
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Jongcheol Seo
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Eunsung Lee
- Department of Chemistry, Seoul National University (SNU), Seoul, 08826, Republic of Korea.
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
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2
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Das A, Saha S, Maji S, Sarkar P, Jose A, Bhatt MM, Bhunia A, Dutta A, Pati SK, Mandal SK. Highly Stable Self-Regenerating Organic Multi-Redox Systems derived from Bicyclic (Alkyl)(amino)carbenes (BICAACs). Chemistry 2024; 30:e202303411. [PMID: 38441342 DOI: 10.1002/chem.202303411] [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: 02/07/2024] [Indexed: 04/04/2024]
Abstract
An extended class of organic multi-redox systems was derived from bicyclic(alkyl)amino carbenes (BICAACs). The highly-conjugated system undergoes a total of 4 redox events spanning a 1.8 V redox range. These organic compounds exhibited four different stable redox states (dication, radical cation, neutral and radical anion), and all of them were characterized either by single crystal X-ray study and/or various spectroscopic studies. Three of the four redox states are stable to air and moisture. The availability of stable multiple redox states demonstrated promise towards their efficacy in the symmetric H-cell charge/discharge cycling. Among various redox states, the dication/neutral state works efficiently and continuously for 1500 cycles in 2e- charge/discharge process outside glovebox in commercially available DMF with minimum capacity loss (retaining nearly 90 % Coulombic efficiency). Surprisingly, the efficiency of the redox cycle was retained even if the system was exposed to air for 30 days when it slowly regenerated to the initial deep blue radical cation, and it exhibited another 100 charge/discharge cycles with a minimal capacity loss. Such a stable H-cell cycling ability is not well known among organic molecule-based systems.
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Affiliation(s)
- Arpan Das
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, Nadia, India
| | - Sukanta Saha
- Chemistry Department, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Subir Maji
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, Nadia, India
| | - Pallavi Sarkar
- Theoretical Sciences Unit, Jawaharlal Nehru Center for Advanced Scientific Research, Bangalore, 560064, India
| | - Anex Jose
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, Nadia, India
| | - Madhur Mahesh Bhatt
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, Nadia, India
| | - Anup Bhunia
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, Nadia, India
| | - Arnab Dutta
- Chemistry Department, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Swapan K Pati
- Theoretical Sciences Unit, Jawaharlal Nehru Center for Advanced Scientific Research, Bangalore, 560064, India
| | - Swadhin K Mandal
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, Nadia, India
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3
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Mao X, Qiu S, Guo R, Dai Y, Zhang J, Kong L, Xie Z. Cyclic (Alkyl)(Amino)Carbene-Iminoboryl Compounds with Three Formal Oxidation States. J Am Chem Soc 2024; 146:10917-10924. [PMID: 38587904 DOI: 10.1021/jacs.4c01934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2024]
Abstract
BN/CC isosterism is an effective strategy to build hybrid functional molecules with unique properties. In contrast to the alkynyl iminium salts derived from cyclic (alkyl)(amino)carbenes (CAACs) that feature only one reversible reduction wave, the isoelectronic cationic CAAC-iminoboryl adducts could be singly and doubly reduced smoothly. Both the resultant neutral radical and anionic azaborataallenes bear NBC-mixed allenic structures. The former radical has a high spin-density of 0.55e at CCAAC carbon, yet exhibits formal boron-centered radical reactivity. The latter azaborataallenes feature the nucleophilic CCAAC center and polar N(δ-)═B(δ+)═C(δ-) unit, and readily undergo nucleophilic substitution, isocyanide insertion, dipolar addition and cycloaddition reactions etc. The N-substituents have been shown to have a significant influence on the solid-state structure, thermal stability, and reactivity of azaborataallenes. This work showcases the allenic BN-unsaturated species as versatile building blocks in organic synthesis.
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Affiliation(s)
- Xiaofeng Mao
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong 999077, China
| | - Shuang Qiu
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China
| | - Rui Guo
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China
| | - Yuyang Dai
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China
| | - Jie Zhang
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong 999077, China
| | - Lingbing Kong
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China
| | - Zuowei Xie
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong 999077, China
- Shenzhen Grubbs Institute and Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, China
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4
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Nayak MK, Elvers BJ, Mehta S, Krummenacher I, Mondal A, Braunschweig H, Schulzke C, Ravat P, Jana A. Bis-[cyclic(alkyl)(amino)carbene]-derived diradicals. Chem Commun (Camb) 2024; 60:1739-1742. [PMID: 38240479 DOI: 10.1039/d3cc05779h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Crystalline polymeric structures of trans-1,4-cyclohexylene bridged N-tethered bis-CAACs in the form of their LiOTf adducts were synthesized and isolated. These were further used as building blocks for the synthesis of crystalline (amino)(carboxy)-based diradicals. The triplet diradical character of these compounds was unambiguously confirmed by the presence of a half-field signal in their EPR spectra. Theoretical calculations show that the singlet state is marginally more stable than the triplet state.
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Affiliation(s)
- Mithilesh Kumar Nayak
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad-500107, India.
| | - Benedict J Elvers
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Straße 4, D-17489, Greifswald, Germany.
| | - Sakshi Mehta
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, 560012, India.
| | - Ivo Krummenacher
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
| | - Abhishake Mondal
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, 560012, India.
| | - Holger Braunschweig
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
| | - Carola Schulzke
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Straße 4, D-17489, Greifswald, Germany.
| | - Prince Ravat
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany.
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad-500107, India.
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5
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Sun Q, Chen H, Zhao Y, Wang T, Pei R, Zhao Y, Ye S, Wang X. A Discrete, Boron-Containing Triangular Triradical. Chemistry 2024; 30:e202302582. [PMID: 37842967 DOI: 10.1002/chem.202302582] [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: 08/08/2023] [Revised: 10/11/2023] [Accepted: 10/13/2023] [Indexed: 10/17/2023]
Abstract
A neutral boron-containing triangular triradical based on a triptycene derivative has been designed and synthesized. Its structure, bonding and physical property have been studied by EPR spectroscopy, SQUID magnetometry and single crystal X-ray diffraction, as well as theoretical calculations. The triradical has a series of isosceles triangle conformations in the solution due to the Jahn-Teller distortion, leading to the splitting of the two low-lying doublet states. This factor together with negligible spin-orbit coupling (SOC) of composing light atoms quenches the spin frustration. The work represents a rare example of a neutral through-space triangular triradical.
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Affiliation(s)
- Quanchun Sun
- State Key Laboratory of Coordination Chemistry Jiangsu Key Laboratory of Advanced Organic Materials School of Chemistry and Chemical Engineering Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, China
| | - Haowen Chen
- State Key Laboratory of Catalysis Dalian Institute of Chemical Physics University of Chinese Academy of Sciences, Chinese Academy of Sciences, Dalian, 116023, China
| | - Yu Zhao
- State Key Laboratory of Coordination Chemistry Jiangsu Key Laboratory of Advanced Organic Materials 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 Jiangsu Key Laboratory of Advanced Organic Materials 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 Jiangsu Key Laboratory of Advanced Organic Materials 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 Jiangsu Key Laboratory of Advanced Organic Materials School of Chemistry and Chemical Engineering Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, China
| | - Shengfa Ye
- State Key Laboratory of Catalysis Dalian Institute of Chemical Physics University of Chinese Academy of Sciences, Chinese Academy of Sciences, Dalian, 116023, China
| | - Xinping Wang
- State Key Laboratory of Coordination Chemistry Jiangsu Key Laboratory of Advanced Organic Materials School of Chemistry and Chemical Engineering Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, China
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6
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Abstract
Robust organic triradicals with high-spin quartet ground states provide promising applications in molecular magnets, spintronics, etc. In this context, a triradical based on Blatter's radical has been synthesized recently, having two low-lying non-degenerate doublet states with a quartet ground state. The traditional broken-symmetry (BS)-DFT computed doublet-quartet energy gaps are reported to be somewhat overestimated in comparison to the experimentally observed values. In this work, we have employed different ab initio methods on this prototypical system to obtain more accurate doublet-quartet energy gaps for this triradical. The spin-constraint broken-symmetry (CBS)-DFT method has been used to reduce the overestimation of energy gaps from BS-DFT. To address the issues of spin-contamination and the multireference nature of low-spin states affecting the DFT methods, we have computed the energy gaps using appropriately state-averaged CASSCF and NEVPT2 computations. Using a series of active spaces, our calculations are shown to provide quite accurate values in concordance with the experimentally observed results. Furthermore, we have proposed and modeled another two triradicals based on Blatter's radical, which are of interest for experimental synthesis and characterization. Our computations show that all these triradicals also have a quartet ground state with a similar energy difference between the excited doublet states.
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Affiliation(s)
- Rishu Khurana
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab 140306, India
| | - Ashima Bajaj
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab 140306, India
| | - K R Shamasundar
- Indian Institute of Science Education and Research Mohali, Sector-81, Mohali, Punjab 140306, India
| | - Md Ehesan Ali
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab 140306, India
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7
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Dong X, Luo QC, Zhao Y, Wang T, Sun Q, Pei R, Zhao Y, Zheng YZ, Wang X. A Dynamic Triradical: Synthesis, Crystal Structure, and Spin Frustration. J Am Chem Soc 2023; 145:17292-17298. [PMID: 37493570 DOI: 10.1021/jacs.3c04692] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2023]
Abstract
Polyradicals, i.e., multispin organic molecules, are playing important roles in radical-based material applications for their spin-spin interaction. A dynamic covalently bonded multispin molecule may endow materials with added function such as memory and switching. However, such a species has yet to be reported. We here report the synthesis, characterization, and crystal structure of a dynamic triradical species. It is generated by the self-assembly of two molecules through a Lewis acid coupled electron transfer. The crystalline species is spin-frustrated without Jahn-Teller distortion at low temperature, while it dissociates back to diamagnetic starting material in solution at high temperature. The reversible process is tracked by variable-temperature NMR, EPR, and UV-vis-NIR spectroscopy. Isolation, property study, and dynamic bonding investigation on such a species lay the foundation for the design of functional polyradicals with potential application as memory or switching devices.
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Affiliation(s)
- Xue Dong
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Science, Shanghai 200032, China
| | - Qian-Cheng Luo
- Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China
| | - Yu Zhao
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Tao Wang
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Quanchun Sun
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Runbo Pei
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Yue Zhao
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Yan-Zhen Zheng
- Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China
| | - Xinping Wang
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, 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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8
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Nayak MK, Elvers BJ, Mandal D, Das A, Ramakrishnan R, Mote KR, Schulzke C, Yildiz CB, Jana A. Reduction of 2- H-substituted pyrrolinium cations: the carbon-carbon single bond in air stable 2,2'-bipyrrolidines as a two-electron-source. Chem Commun (Camb) 2023; 59:6698-6701. [PMID: 37183853 DOI: 10.1039/d3cc00891f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Reduction of 2-H-substituted pyrrolinium cations via initially formed secondary radicals results in either dimerisation or H-abstracted products, while the outcome depends on the N-substituents. The resultant central carbon-carbon single bond in the dimerised 2,2'-bipyrrolidine derivatives can be oxidised chemically and electrochemically. The notably air and moisture-stable dimers were subsequently utilised as a source of two electrons in various chemical transformations.
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Affiliation(s)
- Mithilesh Kumar Nayak
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad-500046, Telangana, India.
| | - Benedict J Elvers
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Straße 4, Greifswald D-17489, Germany.
| | - Debdeep Mandal
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad-500046, Telangana, India.
| | - Ayan Das
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad-500046, Telangana, India.
| | - Raghunathan Ramakrishnan
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad-500046, Telangana, India.
| | - Kaustubh R Mote
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad-500046, Telangana, India.
| | - Carola Schulzke
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Straße 4, Greifswald D-17489, Germany.
| | - Cem Burak Yildiz
- Department of Aromatic and Medicinal Plants, Aksaray University, Aksaray-68100, Türkiye.
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad-500046, Telangana, India.
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9
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Merschel A, Rottschäfer D, Neumann B, Stammler HG, Ringenberg M, van Gastel M, Demirer TI, Andrada DM, Ghadwal RS. Crystalline Anions Based on Classical N-Heterocyclic Carbenes. Angew Chem Int Ed Engl 2023; 62:e202215244. [PMID: 36398890 PMCID: PMC10107637 DOI: 10.1002/anie.202215244] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 11/18/2022] [Accepted: 11/18/2022] [Indexed: 11/19/2022]
Abstract
Herein, the first stable anions K[SIPrBp ] (4 a-K) and K[IPrBp ] (4 b-K) (SIPrBp =BpC{N(Dipp)CH2 }2 , IPrBp =BpC{N(Dipp)CH}2 ; Bp=4-PhC6 H4 ; Dipp=2,6-iPr2 C6 H3 ) derived from classical N-heterocyclic carbenes (NHCs) (i.e. SIPr and IPr) have been isolated as violet crystalline solids. 4 a-K and 4 b-K are prepared by KC8 reduction of the neutral radicals [SIPrBp ] (3 a) and [IPrBp ] (3 b), respectively. The radicals 3 a and 3 b as well as [Me-IPrBp ] 3 c (Me-IPrBp =BpC{N(Dipp)CMe}2 ) are accessible as crystalline solids on treatment of the respective 1,3-imidazoli(ni)um bromides (SIPrBp )Br (2 a), (IPrBp )Br (2 b), and (Me-IPrBp )Br (2 c) with KC8 . The cyclic voltammograms of 2 a-2 c exhibit two one-electron reversible redox processes in -0.5 to -2.5 V region that correspond to the radicals 3 a-3 c and the anions (4 a-4 c)- . Computational calculations suggest a closed-shell singlet ground state for (4 a-4 c)- with the singlet-triplet energy gap of 17-24 kcal mol-1 .
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Affiliation(s)
- Arne Merschel
- Anorganische Molekülchemie und Katalyse, Lehrstuhl für Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, 33615, Bielefeld, Germany
| | - Dennis Rottschäfer
- Anorganische Molekülchemie und Katalyse, Lehrstuhl für Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, 33615, Bielefeld, Germany.,Current address: Department of Chemistry, Philipps-University Marburg, Hans-Meerwein-Str. 4, Marburg, Germany
| | - Beate Neumann
- Anorganische Molekülchemie und Katalyse, Lehrstuhl für Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, 33615, Bielefeld, Germany
| | - Hans-Georg Stammler
- Anorganische Molekülchemie und Katalyse, Lehrstuhl für Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, 33615, Bielefeld, Germany
| | - Mark Ringenberg
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany
| | - Maurice van Gastel
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim a. d. Ruhr, Germany
| | - T Ilgin Demirer
- Allgemeine und Anorganische Chemie, Universität des Saarlandes, 66123, Saarbrücken, Germany
| | - Diego M Andrada
- Allgemeine und Anorganische Chemie, Universität des Saarlandes, 66123, Saarbrücken, Germany
| | - Rajendra S Ghadwal
- Anorganische Molekülchemie und Katalyse, Lehrstuhl für Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, 33615, Bielefeld, Germany
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10
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Peltier JL, Serrato MR, Thery V, Pecaut J, Tomás-Mendivil E, Bertrand G, Jazzar R, Martin D. An air-stable radical with a redox-chameleonic amide. Chem Commun (Camb) 2023; 59:595-598. [PMID: 36524847 DOI: 10.1039/d2cc05404c] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
An air-stable (amino)(amido)radical was synthesized by reacting a cyclic (alkyl)(amino)carbene with carbazoyl chloride, followed by one-electron reduction. We show that an adjacent radical center weakens the amide bond. It enables the amino group to act as a strong acceptor under steric contraint, thus enhancing the stabilizing capto-dative effect.
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Affiliation(s)
- Jesse L Peltier
- UCSD-CNRS Joint Research Chemistry Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093-0358, USA
| | - Melinda R Serrato
- UCSD-CNRS Joint Research Chemistry Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093-0358, USA
| | - Valentin Thery
- University Grenoble Alpes, CNRS, DCM, Grenoble 38000, France.
| | - Jacques Pecaut
- University Grenoble Alpes, CEA, CNRS, INAC-SyMMES, UMR 5819, Grenoble 38000, France
| | | | - Guy Bertrand
- UCSD-CNRS Joint Research Chemistry Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093-0358, USA
| | - Rodolphe Jazzar
- UCSD-CNRS Joint Research Chemistry Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093-0358, USA
| | - David Martin
- University Grenoble Alpes, CNRS, DCM, Grenoble 38000, France.
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11
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Wang L, Sun J, Xia J, Ma R, Zheng G, Zhang Q. Visible light-mediated NHC and photoredox co-catalyzed 1,2-sulfonylacylation of allenes via acyl and allyl radical cross-coupling. Org Chem Front 2023. [DOI: 10.1039/d2qo01993k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Visible light-mediated NHC and photoredox co-catalyzed radical 1,2-sulfonylacylation of allenes via cross-coupling between an allyl radical and an NHC-stabilized acyl radical.
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Affiliation(s)
- Lihong Wang
- Jilin Province Key Laboratory of Organic Functional Molecular Design & Synthesis, Department of ChemistryNortheast Normal University, Changchun 130024, China
| | - Jiaqiong Sun
- School of Environment, Northeast Normal University, Changchun 130117, China
| | - Jiuli Xia
- Jilin Province Key Laboratory of Organic Functional Molecular Design & Synthesis, Department of ChemistryNortheast Normal University, Changchun 130024, China
| | - Ruiyang Ma
- Jilin Province Key Laboratory of Organic Functional Molecular Design & Synthesis, Department of ChemistryNortheast Normal University, Changchun 130024, China
| | - Guangfan Zheng
- Jilin Province Key Laboratory of Organic Functional Molecular Design & Synthesis, Department of ChemistryNortheast Normal University, Changchun 130024, China
| | - Qian Zhang
- Jilin Province Key Laboratory of Organic Functional Molecular Design & Synthesis, Department of ChemistryNortheast Normal University, Changchun 130024, China
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Lu, Shanghai 200032, China
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12
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Nayak MK, Sarkar P, Elvers BJ, Mehta S, Zhang F, Chrysochos N, Krummenacher I, Vijayakanth T, Narayanan RS, Dolai R, Roy B, Malik V, Rawat H, Mondal A, Boomishankar R, Pati SK, Braunschweig H, Schulzke C, Ravat P, Jana A. A bis-NHC-CAAC dimer derived dicationic diradical. Chem Sci 2022; 13:12533-12539. [PMID: 36382295 PMCID: PMC9629079 DOI: 10.1039/d2sc03937k] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 09/21/2022] [Indexed: 08/11/2023] Open
Abstract
The isolation of carbon-centered diradicals is always challenging due to synthetic difficulties and their limited stability. Herein we report the synthesis of a trans-1,4-cyclohexylene bridged bis-NHC-CAAC dimer derived thermally stable dicationic diradical. The diradical character of this compound was confirmed by EPR spectroscopy. The variable temperature EPR study suggests the singlet state to be marginally more stable than the triplet state (2J = -5.5 cm-1 (ΔE ST = 0.065 kJ mol-1)). The presence of the trans-1,4-cyclohexylene bridge is instrumental for the successful isolation of this dicationic diradical. Notably, in the case of ethylene or propylene bridged bis-NHC-CAAC dimers, the corresponding dicationic diradicals are transient and rearrange to hydrogen abstracted products.
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Affiliation(s)
| | - Pallavi Sarkar
- Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research Bangalore-560064 India
| | - Benedict J Elvers
- Institut für Biochemie, Universität Greifswald Felix-Hausdorff-Straße 4 D-17489, Greifswald Germany
| | - Sakshi Mehta
- Solid State and Structural Chemistry Unit, Indian Institute of Science Bangalore 560012 India
| | - Fangyuan Zhang
- Institute of Organic Chemistry, University of Würzburg Am Hubland 97074 Würzburg Germany
| | - Nicolas Chrysochos
- Tata Institute of Fundamental Research Hyderabad Gopanpally Hyderabad-500107 India
| | - Ivo Krummenacher
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
| | - Thangavel Vijayakanth
- Department of Chemistry, Indian Institute of Science Education and Research Pune Dr Homi Bhabha Road Pune 411008 India
| | | | - Ramapada Dolai
- Tata Institute of Fundamental Research Hyderabad Gopanpally Hyderabad-500107 India
| | - Biswarup Roy
- Tata Institute of Fundamental Research Hyderabad Gopanpally Hyderabad-500107 India
| | - Vishal Malik
- Tata Institute of Fundamental Research Hyderabad Gopanpally Hyderabad-500107 India
| | - Hemant Rawat
- Tata Institute of Fundamental Research Hyderabad Gopanpally Hyderabad-500107 India
| | - Abhishake Mondal
- Solid State and Structural Chemistry Unit, Indian Institute of Science Bangalore 560012 India
| | - Ramamoorthy Boomishankar
- Department of Chemistry, Indian Institute of Science Education and Research Pune Dr Homi Bhabha Road Pune 411008 India
| | - Swapan K Pati
- Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research Bangalore-560064 India
| | - Holger Braunschweig
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
| | - Carola Schulzke
- Institut für Biochemie, Universität Greifswald Felix-Hausdorff-Straße 4 D-17489, Greifswald Germany
| | - Prince Ravat
- Institute of Organic Chemistry, University of Würzburg Am Hubland 97074 Würzburg Germany
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad Gopanpally Hyderabad-500107 India
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13
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Design strategy for redox-active organic materials derived from N-heterocyclic carbenes. TRENDS IN CHEMISTRY 2022. [DOI: 10.1016/j.trechm.2022.10.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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14
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Breitwieser K, Bahmann H, Weiss R, Munz D. Gauging Radical Stabilization with Carbenes. Angew Chem Int Ed Engl 2022; 61:e202206390. [PMID: 35796423 PMCID: PMC9545232 DOI: 10.1002/anie.202206390] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Indexed: 11/29/2022]
Abstract
Carbenes, including N‐heterocyclic carbene (NHC) ligands, are used extensively to stabilize open‐shell transition metal complexes and organic radicals. Yet, it remains unknown, which carbene stabilizes a radical well and, thus, how to design radical‐stabilizing C‐donor ligands. With the large variety of C‐donor ligands experimentally investigated and their electronic properties established, we report herein their radical‐stabilizing effect. We show that radical stabilization can be understood by a captodative frontier orbital description involving π‐donation to‐ and π‐donation from the carbenes. This picture sheds a new perspective on NHC chemistry, where π‐donor effects usually are assumed to be negligible. Further, it allows for the intuitive prediction of the thermodynamic stability of covalent radicals of main group‐ and transition metal carbene complexes, and the quantification of redox non‐innocence.
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Affiliation(s)
- Kevin Breitwieser
- Coordination Chemistry Saarland University Campus C4.1 66123 Saarbrücken Germany
| | - Hilke Bahmann
- Physical and Theoretical Chemistry Saarland University Campus B2.2 66123 Saarbrücken Germany
| | - Robert Weiss
- Organische Chemie Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg Henkestr. 42 91054 Erlangen Germany
| | - Dominik Munz
- Coordination Chemistry Saarland University Campus C4.1 66123 Saarbrücken Germany
- Inorganic and General Chemistry Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg Egerlandstr. 1 91058 Erlangen Germany
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15
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Breitwieser K, Bahmann H, Weiss R, Munz D. Gauging Radical Stabilization with Carbenes. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202206390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Kevin Breitwieser
- Saarland University: Universitat des Saarlandes Coordination Chemistry GERMANY
| | - Hilke Bahmann
- Saarland University: Universitat des Saarlandes Theoretical Chemistry GERMANY
| | - Robert Weiss
- FAU Erlangen Nuremberg: Friedrich-Alexander-Universitat Erlangen-Nurnberg Organic Chemistry GERMANY
| | - Dominik Munz
- Universitat des Saarlandes Inorganic Chemistry: Coordination Chemistry Campus C 4.1 66123 Saarbrücken GERMANY
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16
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Wang L, Ma R, Sun J, Zheng G, Zhang Q. NHC and visible light-mediated photoredox co-catalyzed 1,4-sulfonylacylation of 1,3-enynes for tetrasubstituted allenyl ketones. Chem Sci 2022; 13:3169-3175. [PMID: 35414881 PMCID: PMC8926198 DOI: 10.1039/d1sc06100c] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 02/06/2022] [Indexed: 11/21/2022] Open
Abstract
The modulation of selectivity of highly reactive carbon radical cross-coupling for the construction of C-C bonds represents a challenging task in organic chemistry. N-Heterocyclic carbene (NHC) catalyzed radical transformations have opened a new avenue for acyl radical cross-coupling chemistry. With this method, highly selective cross-coupling of an acyl radical with an alkyl radical for efficient construction of C-C bonds was successfully realized. However, the cross-coupling reaction of acyl radicals with vinyl radicals has been much less investigated. We herein describe NHC and visible light-mediated photoredox co-catalyzed radical 1,4-sulfonylacylation of 1,3-enynes, providing structurally diversified valuable tetrasubstituted allenyl ketones. Mechanistic studies indicated that ketyl radicals are formed from aroyl fluorides via the oxidative quenching of the photocatalyst excited state, allenyl radicals are generated from chemo-specific sulfonyl radical addition to the 1,3-enynes, and finally, the key allenyl and ketyl radical cross-coupling provides tetrasubstituted allenyl ketones.
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Affiliation(s)
- Lihong Wang
- Jilin Province Key Laboratory of Organic Functional Molecular Design & Synthesis, Department of ChemistryNortheast Normal University Changchun 130024 China
| | - Ruiyang Ma
- Jilin Province Key Laboratory of Organic Functional Molecular Design & Synthesis, Department of ChemistryNortheast Normal University Changchun 130024 China
| | - Jiaqiong Sun
- School of Environment, Northeast Normal University Changchun 130117 China
| | - Guangfan Zheng
- Jilin Province Key Laboratory of Organic Functional Molecular Design & Synthesis, Department of ChemistryNortheast Normal University Changchun 130024 China
| | - Qian Zhang
- Jilin Province Key Laboratory of Organic Functional Molecular Design & Synthesis, Department of ChemistryNortheast Normal University Changchun 130024 China
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences 345 Lingling Lu Shanghai 200032 China
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17
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Tang S, Ruan H, Hu Z, Zhao Y, Song Y, Wang X. A cationic sulfur-hydrocarbon triradical with an excited quartet state. Chem Commun (Camb) 2022; 58:1986-1989. [PMID: 35045147 DOI: 10.1039/d1cc06904g] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The triptycene-bridged tris(thianthrene) compound 1 was designed and synthesized. Three-electron oxidation of 1 by NO[Al(OC(CF3)3)4], followed by crystallization at two different temperatures resulted in the triradical trication salts 2a and 2b respectively, which feature different crystal packing patterns. The triradical trications in 2a and 2b both feature a doublet ground state which can be thermally populated to a quartet state, representing the first examples of cationic main-group triradicals.
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Affiliation(s)
- Shuxuan Tang
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210023, China.
| | - Huapeng Ruan
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210023, China.
| | - Zhaobo Hu
- 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.
| | - You Song
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210023, 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.
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18
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Cyclic (alkyl)(amino)carbene (CAAC) ligands: Electronic structure and application as chemically- and redox-non-innocent ligands and chromophores. ADVANCES IN ORGANOMETALLIC CHEMISTRY 2022. [DOI: 10.1016/bs.adomc.2022.03.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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19
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Théry V, Molton F, Sirach S, Tillet N, Pécaut J, Tomás-Mendivil E, Martin D. The curious case of a sterically crowded Stenhouse salt. Chem Sci 2022; 13:9755-9760. [PMID: 36091895 PMCID: PMC9400627 DOI: 10.1039/d2sc01895k] [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: 04/01/2022] [Accepted: 07/27/2022] [Indexed: 11/23/2022] Open
Abstract
We report a peculiar Stenhouse salt. It does not evolve into cyclopentenones upon basification, due to the steric hindrance of its bulky stable carbene patterns. This allowed for the observation and characterization of the transient open-chain neutral derivative, which was isolated as its cyclized form. The latter features an unusually long reactive C–O bond (150 pm) and a rich electrochemistry, including oxidation into an air-persistent radical cation. Bulky substituents of a Stenhouse salt prevent the usual formation of a cyclopentenone upon deprotonation. For the first time, a transient open-chain neutral derivative was observed; the cyclized form and an air-persistent radical were isolated.![]()
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Affiliation(s)
| | | | - Selim Sirach
- Univ. Grenoble Alpes, CNRS, DCM Grenoble 38000 France
| | - Neven Tillet
- Univ. Grenoble Alpes, CNRS, DCM Grenoble 38000 France
| | - Jacques Pécaut
- Univ. Grenoble Alpes, CEA, CNRS, INAC-SyMMES, UMR 5819 Grenoble 38000 France
| | | | - David Martin
- Univ. Grenoble Alpes, CNRS, DCM Grenoble 38000 France
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20
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Delfau L, Nichilo S, Molton F, Broggi J, Tomás‐Mendivil E, Martin D. Critical Assessment of the Reducing Ability of Breslow‐type Derivatives and Implications for Carbene‐Catalyzed Radical Reactions**. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202111988] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
| | | | | | - Julie Broggi
- Aix Marseille Univ CNRS Institut de Chimie Radicalaire (ICR) 27 Bd Jean Moulin 13385 Marseille France
| | | | - David Martin
- Univ. Grenoble Alpes CNRS DCM 38000 Grenoble France
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21
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Delfau L, Nichilo S, Molton F, Broggi J, Tomás-Mendivil E, Martin D. Critical Assessment of the Reducing Ability of Breslow-type Derivatives and Implications for Carbene-Catalyzed Radical Reactions*. Angew Chem Int Ed Engl 2021; 60:26783-26789. [PMID: 34651408 PMCID: PMC9299025 DOI: 10.1002/anie.202111988] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Indexed: 01/05/2023]
Abstract
We report the synthesis of acyl azolium salts stemming from thiazolylidenes CNS, triazolylidenes CTN, mesoionic carbenes CMIC and the generation of their corresponding radicals and enolates, covering about 60 Breslow‐type derivatives. This study highlights the role of additives in the redox behavior of these compounds and unveils several critical misconceptions about radical transformations of aldehyde derivatives under N‐heterocyclic carbene catalysis. In particular, the reducing ability of enolates has been dramatically underestimated in the case of biomimetic CNS. In contrast with previous electrochemical studies, we show that these catalytic intermediates can transfer electrons to iodobenzene within minutes at room temperature. Enols derived from CMIC are not the previously claimed super electron donors, although enolate derivatives of CNS and CMIC are powerful reducing agents.
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Affiliation(s)
| | | | - Florian Molton
- Univ. Grenoble Alpes, CNRS, DCM, 38000, Grenoble, France
| | - Julie Broggi
- Aix Marseille Univ, CNRS, Institut de Chimie Radicalaire (ICR), 27 Bd Jean Moulin, 13385, Marseille, France
| | | | - David Martin
- Univ. Grenoble Alpes, CNRS, DCM, 38000, Grenoble, France
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22
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Zhao J, Li X, Han YF. Air-/Heat-Stable Crystalline Carbon-Centered Radicals Derived from an Annelated N-Heterocyclic Carbene. J Am Chem Soc 2021; 143:14428-14432. [PMID: 34469133 DOI: 10.1021/jacs.1c06464] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Organic radicals are open-shell species and have been extensively applied to functional materials due to their unique physicochemical properties with unpaired electrons; however, most of them are highly reactive and short-lived. Herein, a series of stable radicals were readily accessed in two steps from a bis(imino)acenaphthene-supported N-heterocyclic carbene (IPr(BIAN)) through enhancing the delocalization of spin density. The IPr(BIAN)-based radicals 3a-c, obtained by reduction of the corresponding iminium salts 2a-c with KC8, have been spectroscopically and crystallographically (3a,c) characterized. DFT calculations indicate that increasing the electron-withdrawing properties of the para substituent on the carbene carbon atom results in the spin density evolving from the acenaphthene ring to the phenyl ring. The IPr(BIAN)-based radicals 3a-c show excellent stability: they have half-lives of 1 week in well-aerated solutions and feature a high thermal decomposition temperature up to 200 °C.
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Affiliation(s)
- Jing Zhao
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, People's Republic of China
| | - Xin Li
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, People's Republic of China
| | - Ying-Feng Han
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, People's Republic of China
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23
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Zhou L, Zhang D, Hu J, Wu Y, Geng J, Hu X. Thermal Dehydrogenation and Hydrolysis of BH3NH3 Catalyzed by Cyclic (Alkyl)(amino)carbene Iridium Complexes under Mild Conditions. Organometallics 2021. [DOI: 10.1021/acs.organomet.1c00302] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Lei Zhou
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People’s Republic of China
| | - Dejin Zhang
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People’s Republic of China
| | - Jinling Hu
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People’s Republic of China
| | - Youting Wu
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People’s Republic of China
| | - Jiao Geng
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People’s Republic of China
| | - Xingbang Hu
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People’s Republic of China
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24
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Kim Y, Byeon JE, Jeong GY, Kim SS, Song H, Lee E. Highly Stable 1,2-Dicarbonyl Radical Cations Derived from N-Heterocyclic Carbenes. J Am Chem Soc 2021; 143:8527-8532. [PMID: 33974426 DOI: 10.1021/jacs.1c00707] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Stable organic radicals have been of great academic interest not only in the context of fundamental understanding of reactive intermediates but also because of their numerous applications as functional materials. Apart from the early examples of triphenylmethyl and TEMPO derivatives, reports on air- and water-stable organic radicals are scarce, and their development remains a challenge. Herein, we present the design and synthesis of a novel organic radical based on a 1,2-dicarbonyl scaffold supported by N-heterocyclic carbenes (NHCs). The presented radical cations exhibit remarkable stability toward various harsh conditions, such as the presence of reactive chemicals (reductants, oxidants, strong acids, and bases) or high temperatures, by far exceeding the stability of triphenylmethyl and TEMPO radicals. In addition, physiological conditions including aqueous buffer and blood serum are tolerated. The steric and electronic stabilization provided by the two NHC moieties enabled the successful design of the highly stable radical.
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Affiliation(s)
- Youngsuk Kim
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
| | - Jung Eun Byeon
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
| | - Gu Yoon Jeong
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
| | - Seoung Su Kim
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
| | - Hayoung Song
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
| | - Eunsung Lee
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
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25
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Nayak MK, Suhr S, Chrysochos N, Rawat H, Schulzke C, Chandrasekhar V, Sarkar B, Jana A. Tethered CAAC-CAAC dimers: oxidation to persistent radical cations and bridging-unit dependent reactivity/stability of the dications. Chem Commun (Camb) 2021; 57:1210-1213. [PMID: 33416055 DOI: 10.1039/d0cc07385g] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Herein, we report tethered cyclic(alkyl)(amino)carbene (CAAC) dimers in which two CAAC-motifs are connected by an ethylene-, trans-1,2-cyclohexylene- and propylene-spacer through their N-centres. The 1-electron oxidized radical cations are isolable, whereas a significant influence of the bridging unit on the chemical reactivity becomes apparent in and with the 2-electron oxidized products.
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Affiliation(s)
- Mithilesh Kumar Nayak
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad-500046, Telangana, India.
| | - Simon Suhr
- Institut für Chemie und Biochemie, Freie Universität Berlin, Fabeckstraße 34-36, 14195 Berlin, Germany and Universität Stuttgart, Fakultät Chemie, Lehrstuhl für Anorganische Koordinationschemie, Institut für Anorganische Chemie, Pfaffenwaldring 55, Stuttgart, D-70569, Germany.
| | - Nicolas Chrysochos
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Straße 4, Greifswald, D-17489, Germany.
| | - Hemant Rawat
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad-500046, Telangana, India.
| | - Carola Schulzke
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Straße 4, Greifswald, D-17489, Germany.
| | - Vadapalli Chandrasekhar
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad-500046, Telangana, India. and Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India.
| | - Biprajit Sarkar
- Institut für Chemie und Biochemie, Freie Universität Berlin, Fabeckstraße 34-36, 14195 Berlin, Germany and Universität Stuttgart, Fakultät Chemie, Lehrstuhl für Anorganische Koordinationschemie, Institut für Anorganische Chemie, Pfaffenwaldring 55, Stuttgart, D-70569, Germany.
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad-500046, Telangana, India.
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26
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Das A, Ahmed J, Rajendran NM, Adhikari D, Mandal SK. A Bottleable Imidazole-Based Radical as a Single Electron Transfer Reagent. J Org Chem 2021; 86:1246-1252. [PMID: 33280378 DOI: 10.1021/acs.joc.0c02465] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Reduction of 1,3-bis(2,6-diisopropylphenyl)-2,4-diphenyl-1H-imidazol-3-ium chloride (1) resulted in the formation of the first structurally characterized imidazole-based radical 2. 2 was established as a single electron transfer reagent by treating it with an acceptor molecule tetracyanoethylene. Moreover, radical 2 was utilized as an organic electron donor in a number of organic transformations such as in activation of an aryl-halide bond, alkene hydrosilylation, and in catalytic reduction of CO2 to methoxyborane, all under ambient temperature and pressure.
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Affiliation(s)
- Arpan Das
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India
| | - Jasimuddin Ahmed
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India
| | - N M Rajendran
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India
| | - Debashis Adhikari
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, SAS Nagar, 140306, India
| | - Swadhin K Mandal
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India
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27
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Guthardt R, Bruhn C, Siemeling U. N-heterocyclic olefins as dative carbon donor ligands for diaminoplumbylenes: Syntheses and crystal structures of adducts with 1,3,4,5-tetramethyl-2-methyleneimidazoline. Polyhedron 2021. [DOI: 10.1016/j.poly.2020.114959] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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28
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Pinter P, Munz D. Controlling Möbius-Type Helicity and the Excited-State Properties of Cumulenes with Carbenes. J Phys Chem A 2020; 124:10100-10110. [DOI: 10.1021/acs.jpca.0c07940] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Piermaria Pinter
- Department of Chemistry and Pharmacy, General and Inorganic Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 1, 91058 Erlangen, Germany
| | - Dominik Munz
- Inorganic Chemistry: Coordination Chemistry, Saarland University, Campus Geb. C4.1, 66123 Saarbrücken, Germany
- Department of Chemistry and Pharmacy, General and Inorganic Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 1, 91058 Erlangen, Germany
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29
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Saalfrank C, Fantuzzi F, Kupfer T, Ritschel B, Hammond K, Krummenacher I, Bertermann R, Wirthensohn R, Finze M, Schmid P, Engel V, Engels B, Braunschweig H. cAAC-Stabilized 9,10-diboraanthracenes-Acenes with Open-Shell Singlet Biradical Ground States. Angew Chem Int Ed Engl 2020; 59:19338-19343. [PMID: 32662218 PMCID: PMC7589216 DOI: 10.1002/anie.202008206] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Indexed: 12/19/2022]
Abstract
Narrow HOMO-LUMO gaps and high charge-carrier mobilities make larger acenes potentially high-efficient materials for organic electronic applications. The performance of such molecules was shown to significantly increase with increasing number of fused benzene rings. Bulk quantities, however, can only be obtained reliably for acenes up to heptacene. Theoretically, (oligo)acenes and (poly)acenes are predicted to have open-shell singlet biradical and polyradical ground states, respectively, for which experimental evidence is still scarce. We have now been able to dramatically lower the HOMO-LUMO gap of acenes without the necessity of unfavorable elongation of their conjugated π system, by incorporating two boron atoms into the anthracene skeleton. Stabilizing the boron centers with cyclic (alkyl)(amino)carbenes gives neutral 9,10-diboraanthracenes, which are shown to feature disjointed, open-shell singlet biradical ground states.
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Affiliation(s)
- Christian Saalfrank
- Institut für Anorganische ChemieJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
- Institute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Felipe Fantuzzi
- Institut für Anorganische ChemieJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
- Institute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
- Institut für Physikalische und Theoretische ChemieJulius-Maximilians-Universität WürzburgEmil-Fischer-Strasse 4297074WürzburgGermany
| | - Thomas Kupfer
- Institut für Anorganische ChemieJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
- Institute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Benedikt Ritschel
- Institut für Anorganische ChemieJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
- Institute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Kai Hammond
- Institut für Anorganische ChemieJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
- Institute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Ivo Krummenacher
- Institut für Anorganische ChemieJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
- Institute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Rüdiger Bertermann
- Institut für Anorganische ChemieJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
- Institute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Raphael Wirthensohn
- Institut für Anorganische ChemieJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
- Institute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Maik Finze
- Institut für Anorganische ChemieJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
- Institute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Paul Schmid
- Institut für Physikalische und Theoretische ChemieJulius-Maximilians-Universität WürzburgEmil-Fischer-Strasse 4297074WürzburgGermany
| | - Volker Engel
- Institut für Physikalische und Theoretische ChemieJulius-Maximilians-Universität WürzburgEmil-Fischer-Strasse 4297074WürzburgGermany
| | - Bernd Engels
- Institut für Physikalische und Theoretische ChemieJulius-Maximilians-Universität WürzburgEmil-Fischer-Strasse 4297074WürzburgGermany
| | - Holger Braunschweig
- Institut für Anorganische ChemieJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
- Institute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
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30
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Saalfrank C, Fantuzzi F, Kupfer T, Ritschel B, Hammond K, Krummenacher I, Bertermann R, Wirthensohn R, Finze M, Schmid P, Engel V, Engels B, Braunschweig H. cAAC‐stabilisierte 9,10‐Diboraanthracene – offenschalige Singulettbiradikale. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202008206] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Christian Saalfrank
- Institut für Anorganische Chemie Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
- Institut für Nachhaltige Chemie & Katalyse mit Bor Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
| | - Felipe Fantuzzi
- Institut für Anorganische Chemie Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
- Institut für Nachhaltige Chemie & Katalyse mit Bor Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
- Institut für Physikalische und Theoretische Chemie Julius-Maximilians-Universität Würzburg Emil-Fischer-Straße 42 97074 Würzburg Germany
| | - Thomas Kupfer
- Institut für Anorganische Chemie Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
- Institut für Nachhaltige Chemie & Katalyse mit Bor Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
| | - Benedikt Ritschel
- Institut für Anorganische Chemie Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
- Institut für Nachhaltige Chemie & Katalyse mit Bor Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
| | - Kai Hammond
- Institut für Anorganische Chemie Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
- Institut für Nachhaltige Chemie & Katalyse mit Bor Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
| | - Ivo Krummenacher
- Institut für Anorganische Chemie Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
- Institut für Nachhaltige Chemie & Katalyse mit Bor Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
| | - Rüdiger Bertermann
- Institut für Anorganische Chemie Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
- Institut für Nachhaltige Chemie & Katalyse mit Bor Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
| | - Raphael Wirthensohn
- Institut für Anorganische Chemie Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
- Institut für Nachhaltige Chemie & Katalyse mit Bor Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
| | - Maik Finze
- Institut für Anorganische Chemie Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
- Institut für Nachhaltige Chemie & Katalyse mit Bor Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
| | - Paul Schmid
- Institut für Physikalische und Theoretische Chemie Julius-Maximilians-Universität Würzburg Emil-Fischer-Straße 42 97074 Würzburg Germany
| | - Volker Engel
- Institut für Physikalische und Theoretische Chemie Julius-Maximilians-Universität Würzburg Emil-Fischer-Straße 42 97074 Würzburg Germany
| | - Bernd Engels
- Institut für Physikalische und Theoretische Chemie Julius-Maximilians-Universität Würzburg Emil-Fischer-Straße 42 97074 Würzburg Germany
| | - Holger Braunschweig
- Institut für Anorganische Chemie Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
- Institut für Nachhaltige Chemie & Katalyse mit Bor Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
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31
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Mavroskoufis A, Jakob M, Hopkinson MN. Light‐Promoted Organocatalysis with N‐Heterocyclic Carbenes. CHEMPHOTOCHEM 2020. [DOI: 10.1002/cptc.202000120] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Andreas Mavroskoufis
- Institute of Chemistry and Biochemistry Freie Universität Berlin Fabeckstrasse 34–36 14195 Berlin Germany
| | - Michael Jakob
- Institute of Chemistry and Biochemistry Freie Universität Berlin Fabeckstrasse 34–36 14195 Berlin Germany
| | - Matthew N. Hopkinson
- Institute of Chemistry and Biochemistry Freie Universität Berlin Fabeckstrasse 34–36 14195 Berlin Germany
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32
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Maiti A, Stubbe J, Neuman NI, Kalita P, Duari P, Schulzke C, Chandrasekhar V, Sarkar B, Jana A. CAAC‐Based Thiele and Schlenk Hydrocarbons. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201915802] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Avijit Maiti
- Tata Institute of Fundamental Research (TIFR) Hyderabad Gopanpally Hyderabad-500107 Telangana India
| | - Jessica Stubbe
- Institut für Chemie und BiochemieAnorganische ChemieFreie Universität Berlin Fabeckstraße 34–36 14195 Berlin Germany
| | - Nicolás I. Neuman
- Institut für Chemie und BiochemieAnorganische ChemieFreie Universität Berlin Fabeckstraße 34–36 14195 Berlin Germany
- Instituto de Desarrollo Tecnológico para laIndustria Química, CCT Santa Fe CONICET-UNL Colectora Ruta Nacional 168, Km 472, Paraje El Pozo 3000 Santa Fe Argentina
| | - Pankaj Kalita
- Tata Institute of Fundamental Research (TIFR) Hyderabad Gopanpally Hyderabad-500107 Telangana India
| | - Prakash Duari
- Tata Institute of Fundamental Research (TIFR) Hyderabad Gopanpally Hyderabad-500107 Telangana India
| | - Carola Schulzke
- Institut für BiochemieUniversität Greifswald Felix-Hausdorff-Straße 4 17487 Greifswald Germany
| | - Vadapalli Chandrasekhar
- Tata Institute of Fundamental Research (TIFR) Hyderabad Gopanpally Hyderabad-500107 Telangana India
- Department of ChemistryIndian Institute of Technology Kanpur Kanpur 208016 India
| | - Biprajit Sarkar
- Institut für Chemie und BiochemieAnorganische ChemieFreie Universität Berlin Fabeckstraße 34–36 14195 Berlin Germany
- Institut für Anorganische ChemieUniversität Stuttgart Pfaffenwaldring 55 70569 Stuttgart Germany
| | - Anukul Jana
- Tata Institute of Fundamental Research (TIFR) Hyderabad Gopanpally Hyderabad-500107 Telangana India
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33
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Nayak MK, Stubbe J, Neuman NI, Narayanan RS, Maji S, Schulzke C, Chandrasekhar V, Sarkar B, Jana A. N,N'-Ethylene-Bridged Bis-2-Aryl-Pyrrolinium Cations to E-Diaminoalkenes: Non-Identical Stepwise Reversible Double-Redox Coupled Bond Activation Reactions. Chemistry 2020; 26:4425-4431. [PMID: 31994763 PMCID: PMC7187269 DOI: 10.1002/chem.202000255] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Indexed: 12/31/2022]
Abstract
This work presents a stepwise reversible two‐electron transfer induced hydrogen shift leading to the conversion of a bis‐pyrrolinium cation to an E‐diaminoalkene and vice versa. Remarkably, the forward and the reverse reaction, which are both reversible, follow two completely different reaction pathways. Establishing such unprecedented property in this type of processes was possible by developing a novel synthetic route towards the starting dication. All intermediates involved in both the forward and the backward reactions were comprehensively characterized by a combination of spectroscopic, crystallographic, electrochemical, spectroelectrochemical, and theoretical methods. The presented synthetic route opens up new possibilities for the generation of multi‐pyrrolinium cation scaffold‐based organic redox systems, which constitute decidedly sought‐after molecules in contemporary chemistry.
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Affiliation(s)
- Mithilesh Kumar Nayak
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad, 500107, India
| | - Jessica Stubbe
- Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, 14195, Berlin, Germany
| | - Nicolás I Neuman
- Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, 14195, Berlin, Germany.,Instituto de Desarrollo Tecnológico para la Industria Química, CCT Santa Fe CONICET-UNL, Colectora Ruta Nacional 168, Km 472, Paraje El Pozo, 3000, Santa Fe, Argentina
| | | | - Sandipan Maji
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad, 500107, India
| | - Carola Schulzke
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Straße 4, 17487, Greifswald, Germany
| | - Vadapalli Chandrasekhar
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad, 500107, India.,Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Biprajit Sarkar
- Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, 14195, Berlin, Germany.,Institut für Anorganische Chemie, Lehrstuhl für Anorganische Koordinationschemie, Universität Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad, 500107, India
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34
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Maiti A, Stubbe J, Neuman NI, Kalita P, Duari P, Schulzke C, Chandrasekhar V, Sarkar B, Jana A. CAAC-Based Thiele and Schlenk Hydrocarbons. Angew Chem Int Ed Engl 2020; 59:6729-6734. [PMID: 31960562 PMCID: PMC7187164 DOI: 10.1002/anie.201915802] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Indexed: 01/17/2023]
Abstract
Diradicals have been of tremendous interest for over a century ever since the first reports of p- and m-phenylene-bridged diphenylmethylradicals in 1904 by Thiele and 1915 by Schlenk. Reported here are the first examples of cyclic(alkyl)(amino)carbene (CAAC) analogues of Thiele's hydrocarbon, a Kekulé diradical, and Schlenk's hydrocarbon, a non-Kekulé diradical, without using CAAC as a precursor. The CAAC analogue of Thiele's hydrocarbon has a singlet ground state, whereas the CAAC analogue of Schlenk's hydrocarbon contains two unpaired electrons. The latter forms a dimer, by an intermolecular double head-to-tail dimerization. This straightforward synthetic methodology is modular and can be extended for the generation of redox-active organic compounds.
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Affiliation(s)
- Avijit Maiti
- Tata Institute of Fundamental Research (TIFR) Hyderabad, Gopanpally, Hyderabad-500107, Telangana, India
| | - Jessica Stubbe
- Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, 14195, Berlin, Germany
| | - Nicolás I Neuman
- Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, 14195, Berlin, Germany.,Instituto de Desarrollo Tecnológico para la, Industria Química, CCT Santa Fe CONICET-UNL, Colectora Ruta Nacional 168, Km 472, Paraje El Pozo, 3000, Santa Fe, Argentina
| | - Pankaj Kalita
- Tata Institute of Fundamental Research (TIFR) Hyderabad, Gopanpally, Hyderabad-500107, Telangana, India
| | - Prakash Duari
- Tata Institute of Fundamental Research (TIFR) Hyderabad, Gopanpally, Hyderabad-500107, Telangana, India
| | - Carola Schulzke
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Straße 4, 17487, Greifswald, Germany
| | - Vadapalli Chandrasekhar
- Tata Institute of Fundamental Research (TIFR) Hyderabad, Gopanpally, Hyderabad-500107, Telangana, India.,Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Biprajit Sarkar
- Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, 14195, Berlin, Germany.,Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany
| | - Anukul Jana
- Tata Institute of Fundamental Research (TIFR) Hyderabad, Gopanpally, Hyderabad-500107, Telangana, India
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35
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Mavroskoufis A, Rajes K, Golz P, Agrawal A, Ruß V, Götze JP, Hopkinson MN. N-Heterocyclic Carbene Catalyzed Photoenolization/Diels-Alder Reaction of Acid Fluorides. Angew Chem Int Ed Engl 2020; 59:3190-3194. [PMID: 31814280 PMCID: PMC7027522 DOI: 10.1002/anie.201914456] [Citation(s) in RCA: 88] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Indexed: 11/23/2022]
Abstract
The combination of light activation and N-heterocyclic carbene (NHC) organocatalysis has enabled the use of acid fluorides as substrates in a UVA-light-mediated photochemical transformation previously observed only with aromatic aldehydes and ketones. Stoichiometric studies and TD-DFT calculations support a mechanism involving the photoactivation of an ortho-toluoyl azolium intermediate, which exhibits "ketone-like" photochemical reactivity under UVA irradiation. Using this photo-NHC catalysis approach, a novel photoenolization/Diels-Alder (PEDA) process was developed that leads to diverse isochroman-1-one derivatives.
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Affiliation(s)
- Andreas Mavroskoufis
- Institute of Chemistry and BiochemistryFreie Universität BerlinTakustraße 314195BerlinGermany
| | - Keerthana Rajes
- Institute of Chemistry and BiochemistryFreie Universität BerlinTakustraße 314195BerlinGermany
| | - Paul Golz
- Institute of Chemistry and BiochemistryFreie Universität BerlinTakustraße 314195BerlinGermany
| | - Arush Agrawal
- Institute of Chemistry and BiochemistryFreie Universität BerlinTakustraße 314195BerlinGermany
| | - Vincent Ruß
- Institute of Chemistry and BiochemistryFreie Universität BerlinTakustraße 314195BerlinGermany
| | - Jan P. Götze
- Institute of Chemistry and BiochemistryFreie Universität BerlinTakustraße 314195BerlinGermany
| | - Matthew N. Hopkinson
- Institute of Chemistry and BiochemistryFreie Universität BerlinTakustraße 314195BerlinGermany
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36
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Mavroskoufis A, Rajes K, Golz P, Agrawal A, Ruß V, Götze JP, Hopkinson MN. Durch N‐heterocyclische Carbene katalysierte Photoenolisierungs‐Diels‐Alder‐Reaktion von Säurefluoriden. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201914456] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Andreas Mavroskoufis
- Institut für Chemie und Biochemie Freie Universität Berlin Takustraße 3 14195 Berlin Deutschland
| | - Keerthana Rajes
- Institut für Chemie und Biochemie Freie Universität Berlin Takustraße 3 14195 Berlin Deutschland
| | - Paul Golz
- Institut für Chemie und Biochemie Freie Universität Berlin Takustraße 3 14195 Berlin Deutschland
| | - Arush Agrawal
- Institut für Chemie und Biochemie Freie Universität Berlin Takustraße 3 14195 Berlin Deutschland
| | - Vincent Ruß
- Institut für Chemie und Biochemie Freie Universität Berlin Takustraße 3 14195 Berlin Deutschland
| | - Jan P. Götze
- Institut für Chemie und Biochemie Freie Universität Berlin Takustraße 3 14195 Berlin Deutschland
| | - Matthew N. Hopkinson
- Institut für Chemie und Biochemie Freie Universität Berlin Takustraße 3 14195 Berlin Deutschland
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37
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Kundu G, De S, Tothadi S, Das A, Koley D, Sen SS. Saturated N-Heterocyclic Carbene Based Thiele's Hydrocarbon with a Tetrafluorophenylene Linker. Chemistry 2019; 25:16533-16537. [PMID: 31609519 DOI: 10.1002/chem.201904421] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 10/06/2019] [Indexed: 01/24/2023]
Abstract
The synthesis of a SIPr [1,3-bis(2,6-diisopropylphenyl)-imidazolin-2-ylidene] derived Kekulé diradicaloid with a tetrafluorophenylene spacer (3) has been described. Two synthetic routes have been reported to access 3. The cleavage of C-F bond of C6 F6 by SIPr in the presence of BF3 led to double C-F activated compound with two tetrafluoro borate counter anions (2), which upon reduction by lithium metal afforded 3. Alternatively, 3 can be directly accessed in one step by reacting SIPr with C6 F6 in presence of Mg metal. Compounds 2 and 3 were well characterized spectroscopically and by single-crystal X-ray diffraction studies. Experimental and computational studies support the cumulenic closed-shell singlet state of 3 with a singlet-triplet energy gap (ΔES-T ) of 23.7 kcal mol-1 .
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Affiliation(s)
- Gargi Kundu
- Inorganic Chemistry and Catalysis Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India.,Academy of Scientific and Innovative Research (AcSIR), New Ghaziabad, 201002, India
| | - Sriman De
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, 741246, India
| | - Srinu Tothadi
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India
| | - Abhishek Das
- Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Kolkata, 700032, India
| | - Debasis Koley
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, 741246, India
| | - Sakya S Sen
- Inorganic Chemistry and Catalysis Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India.,Academy of Scientific and Innovative Research (AcSIR), New Ghaziabad, 201002, India
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38
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Werr M, Kaifer E, Wadepohl H, Himmel HJ. Tuneable Redox Chemistry and Electrochromism of Persistent Symmetric and Asymmetric Azine Radical Cations. Chemistry 2019; 25:12981-12990. [PMID: 31306523 DOI: 10.1002/chem.201902216] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 06/21/2019] [Indexed: 12/16/2022]
Abstract
Molecular organic radicals have been intensively studied in the last decades, due to their interesting optical, magnetic and redox properties. Here we report the synthesis and characterisation of persistent organic radicals from one-electron oxidation of redox-active azines (RAAs), composed of two guanidinyl or related groups. By connecting two different groups together, asymmetric compounds result. In this way a series of compounds with varying redox potential is obtained that could be oxidised reversibly to the mono- and the dicationic charge states. The accessible redox states were fully determined by chemical redox reactions. The standard Gibbs free energy change for disproportionation of the radical monocation into the dication and the neutral molecule in solution, estimated from cyclovoltammetric measurements, varies between 43 and 71 kJ mol-1 . While the neutral RAAs absorb predominately UV light, the radical monocations display strong absorptions covering almost the entire visible region and extending for some compounds into the NIR region. A detailed analysis of this highly reversible electrochromism is presented, and the fast switching characteristics are demonstrated in an electrochromic test device.
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Affiliation(s)
- Marco Werr
- Anorganisch Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Elisabeth Kaifer
- Anorganisch Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Hubert Wadepohl
- Anorganisch Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Hans-Jörg Himmel
- Anorganisch Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
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39
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Kim Y, Bielawski CW, Lee E. Oxygen atom transfer: a mild and efficient method for generating iminyl radicals. Chem Commun (Camb) 2019; 55:7061-7064. [PMID: 31143894 DOI: 10.1039/c9cc03521d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Treating iminoxyl species with oxygen acceptors such as PPh3 resulted in oxygen atom transfer and afforded the corresponding iminyl radicals. DFT and other calculations revealed that association between the oxygen atom acceptors and the iminoxyl species results in the formation of key intermediates during the reaction. Subsequent dissociation is accompanied with homolytic cleavage of the N-O bond and generates iminyl radicals with spin densities that are localized on exocyclic nitrogen atoms.
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Affiliation(s)
- Youngsuk Kim
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea. and Center for Self-assembly and Complexity (CSC), Institute for Basic Science (IBS), Pohang, 37673, Republic of Korea
| | - Christopher W Bielawski
- Center for Multidimensional Carbon Materials (CMCM), Institute for Basic Science (IBS), Ulsan, 44919, Republic of Korea and Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea and Department of Energy Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Eunsung Lee
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea. and Center for Self-assembly and Complexity (CSC), Institute for Basic Science (IBS), Pohang, 37673, Republic of Korea and Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
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40
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Bharadwaz P, Phukan AK. Introducing N-Heterocyclic Borylenes: Theoretical Prediction of Stable, Neutral, Monomeric Boron(I) Carbenoids. Inorg Chem 2019; 58:5428-5432. [PMID: 30985119 DOI: 10.1021/acs.inorgchem.9b00731] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Quantum-chemical calculations predict that synthetically accessible cyclic four-membered, four-π-electron ylides could be used as building blocks for the realization of hitherto unknown N-heterocyclic boron(I) carbenoids. The boron(I) carbenoids proposed in this work possess the largest computed singlet-triplet separations known to date, which are comparable to those of the corresponding aluminum(I) analogue computed at the same level of theory. Furthermore, they owe their stability not only to the substantial transfer of electron density from nitrogen to boron atoms but also to the presence of thermodynamically robust ylidic bonds. On the basis of their computed proton affinity and carbonyl stretching frequencies, they may be considered as promising ligands for transition-metal complexes.
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Affiliation(s)
- Priyam Bharadwaz
- Department of Chemical Sciences , Tezpur University , Napaam , Assam 784028 , India
| | - Ashwini K Phukan
- Department of Chemical Sciences , Tezpur University , Napaam , Assam 784028 , India
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41
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Affiliation(s)
- Kenichi Kato
- Department of ChemistryGraduate School of ScienceKyoto University Oiwake-cho, Kitashirakawa, Sakyo-ku Kyoto 606-8502 Japan
| | - Atsuhiro Osuka
- Department of ChemistryGraduate School of ScienceKyoto University Oiwake-cho, Kitashirakawa, Sakyo-ku Kyoto 606-8502 Japan
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42
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Kato K, Osuka A. Platforms for Stable Carbon‐Centered Radicals. Angew Chem Int Ed Engl 2019; 58:8978-8986. [DOI: 10.1002/anie.201900307] [Citation(s) in RCA: 84] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Indexed: 11/12/2022]
Affiliation(s)
- Kenichi Kato
- Department of ChemistryGraduate School of ScienceKyoto University Oiwake-cho, Kitashirakawa, Sakyo-ku Kyoto 606-8502 Japan
| | - Atsuhiro Osuka
- Department of ChemistryGraduate School of ScienceKyoto University Oiwake-cho, Kitashirakawa, Sakyo-ku Kyoto 606-8502 Japan
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43
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Kundu S, Sinhababu S, Chandrasekhar V, Roesky HW. Stable cyclic (alkyl)(amino)carbene (cAAC) radicals with main group substituents. Chem Sci 2019; 10:4727-4741. [PMID: 31160949 PMCID: PMC6510188 DOI: 10.1039/c9sc01351b] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 04/06/2019] [Indexed: 11/21/2022] Open
Abstract
Recent attempts to isolate cyclic (alkyl)(amino)carbene stabilized radicals of p-block elements have been described here.
Isolation and characterization of stable radicals has been a long-pursued quest. While there has been some progress in this field particularly with respect to carbon, radicals involving heavier p-block elements are still considerably sparse. In this review we describe our recent successful efforts on the isolation of stable p-block element radicals particularly those involving aluminum, silicon, and phosphorus.
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Affiliation(s)
- Subrata Kundu
- Universität Göttingen , Institut für Anorganische Chemie , Tammannstrasse 4 , D-37077 , Göttingen , Germany .
| | - Soumen Sinhababu
- Universität Göttingen , Institut für Anorganische Chemie , Tammannstrasse 4 , D-37077 , Göttingen , Germany .
| | - Vadapalli Chandrasekhar
- Universität Göttingen , Institut für Anorganische Chemie , Tammannstrasse 4 , D-37077 , Göttingen , Germany . .,Tata Institute of Fundamental Research Hyderabad , Hyderabad 500107 , India.,Department of Chemistry , Indian Institute of Technology Kanpur , Kanpur 208016 , India .
| | - Herbert W Roesky
- Universität Göttingen , Institut für Anorganische Chemie , Tammannstrasse 4 , D-37077 , Göttingen , Germany .
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44
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Mandal D, Sobottka S, Dolai R, Maiti A, Dhara D, Kalita P, Narayanan RS, Chandrasekhar V, Sarkar B, Jana A. Direct access to 2-aryl substituted pyrrolinium salts for carbon centre based radicals without pyrrolidine-2-ylidene alias cyclic(alkyl)(amino)carbene (CAAC) as a precursor. Chem Sci 2019; 10:4077-4081. [PMID: 31049189 PMCID: PMC6470959 DOI: 10.1039/c8sc05477k] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 02/27/2019] [Indexed: 12/20/2022] Open
Abstract
A new strategy to synthesise 2-substituted pyrrolinium salts.
The synthesis of organic radicals is challenging due to their inherent instability. In recent years, cyclic(alkyl)(amino)carbene (CAAC)-derived 2-substituted pyrrolinium salts have been used as synthons for the synthesis of isolable carbon-based radicals. Herein, we report a direct, easy and convenient method for the synthesis of 2-aryl substituted pyrrolinium salts without using CAAC as a precursor. These cations can be reduced to the corresponding radicals. The influence of the aryl substituent at the C-2 position on radical stabilization and dimerization has been investigated. Because of the large scope of our strategy (capability to modulate different substituents at all the C- and N-centres of the pyrrolinium salts), it has the merit to be an extremely effective and productive route for generating carbon-based radicals whose stability as well as reactivity can be varied.
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Affiliation(s)
- Debdeep Mandal
- Tata Institute of Fundamental Research Hyderabad , Gopanpally , Hyderabad-500107 , Telangana , India .
| | - Sebastian Sobottka
- Institut für Chemie und Biochemie, Anorganische Chemie , Freie Universität Berlin , Fabeckstraße 34-36 , 14195 , Berlin , Germany .
| | - Ramapada Dolai
- Tata Institute of Fundamental Research Hyderabad , Gopanpally , Hyderabad-500107 , Telangana , India .
| | - Avijit Maiti
- Tata Institute of Fundamental Research Hyderabad , Gopanpally , Hyderabad-500107 , Telangana , India .
| | - Debabrata Dhara
- Tata Institute of Fundamental Research Hyderabad , Gopanpally , Hyderabad-500107 , Telangana , India .
| | - Pankaj Kalita
- School of Chemical Sciences , National Institute of Science Education and Research , HBNI , Bhubaneswar-752050 , India
| | | | - Vadapalli Chandrasekhar
- Tata Institute of Fundamental Research Hyderabad , Gopanpally , Hyderabad-500107 , Telangana , India . .,Department of Chemistry , Indian Institute of Technology Kanpur , Kanpur-208016 , India .
| | - Biprajit Sarkar
- Institut für Chemie und Biochemie, Anorganische Chemie , Freie Universität Berlin , Fabeckstraße 34-36 , 14195 , Berlin , Germany .
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad , Gopanpally , Hyderabad-500107 , Telangana , India .
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45
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van der Vlugt JI. Radical-Type Reactivity and Catalysis by Single-Electron Transfer to or from Redox-Active Ligands. Chemistry 2019; 25:2651-2662. [PMID: 30084211 PMCID: PMC6471147 DOI: 10.1002/chem.201802606] [Citation(s) in RCA: 127] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Indexed: 12/12/2022]
Abstract
Controlled ligand-based redox-activity and chemical non-innocence are rapidly gaining importance for selective (catalytic) processes. This Concept aims to provide an overview of the progress regarding ligand-to-substrate single-electron transfer as a relatively new mode of operation to exploit ligand-centered reactivity and catalysis based thereon.
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Affiliation(s)
- Jarl Ivar van der Vlugt
- Bio-Inspired Homogeneous and Supramolecular Catalysis Groupvan ‘t Hoff Institute for Molecular SciencesUniversity of AmsterdamScience Park 9041098 XHAmsterdamNetherlands
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46
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Schiegerl LJ, Melaimi M, Tolentino DR, Klein W, Bertrand G, Fässler TF. Silylated Ge9 Clusters as New Ligands for Cyclic (Alkyl)amino and Mesoionic Carbene Copper Complexes. Inorg Chem 2019; 58:3256-3264. [DOI: 10.1021/acs.inorgchem.8b03338] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lorenz J. Schiegerl
- Department of Chemistry, Technische Universität München (TUM), Lichtenbergstraße 4, 85748 Garching, Germany
| | - Mohand Melaimi
- UCSD−CNRS Joint Research Chemistry Laboratory (UMI 3555), University of California—San Diego, La Jolla, California 92093-0353, United States
| | - Daniel R. Tolentino
- UCSD−CNRS Joint Research Chemistry Laboratory (UMI 3555), University of California—San Diego, La Jolla, California 92093-0353, United States
| | - Wilhelm Klein
- Department of Chemistry, Technische Universität München (TUM), Lichtenbergstraße 4, 85748 Garching, Germany
| | - Guy Bertrand
- UCSD−CNRS Joint Research Chemistry Laboratory (UMI 3555), University of California—San Diego, La Jolla, California 92093-0353, United States
| | - Thomas F. Fässler
- Department of Chemistry, Technische Universität München (TUM), Lichtenbergstraße 4, 85748 Garching, Germany
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47
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Deissenberger A, Welz E, Drescher R, Krummenacher I, Dewhurst RD, Engels B, Braunschweig H. A New Class of Neutral Boron‐Based Diradicals Spanned by a Two‐Carbon‐Atom Bridge. Angew Chem Int Ed Engl 2019; 58:1842-1846. [DOI: 10.1002/anie.201813335] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Indexed: 11/12/2022]
Affiliation(s)
- Andrea Deissenberger
- Institute for Inorganic ChemistryJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
- Institute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
| | - Eileen Welz
- Institute for Physical and Theoretical ChemistryJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
| | - Regina Drescher
- Institute for Inorganic ChemistryJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
- Institute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
| | - Ivo Krummenacher
- Institute for Inorganic ChemistryJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
- Institute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
| | - Rian D. Dewhurst
- Institute for Inorganic ChemistryJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
- Institute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
| | - Bernd Engels
- Institute for Physical and Theoretical ChemistryJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
| | - Holger Braunschweig
- Institute for Inorganic ChemistryJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
- Institute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
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48
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Deissenberger A, Welz E, Drescher R, Krummenacher I, Dewhurst RD, Engels B, Braunschweig H. Eine neue Strukturklasse neutraler borhaltiger Diradikale verbrückt über zwei Kohlenstoffatome. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201813335] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Andrea Deissenberger
- Institut für Anorganische ChemieJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Deutschland
- Institut für nachhaltige Chemie & Katalyse mit BorJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Deutschland
| | - Eileen Welz
- Institut für Physikalische und Theoretische ChemieJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Deutschland
| | - Regina Drescher
- Institut für Anorganische ChemieJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Deutschland
- Institut für nachhaltige Chemie & Katalyse mit BorJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Deutschland
| | - Ivo Krummenacher
- Institut für Anorganische ChemieJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Deutschland
- Institut für nachhaltige Chemie & Katalyse mit BorJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Deutschland
| | - Rian D. Dewhurst
- Institut für Anorganische ChemieJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Deutschland
- Institut für nachhaltige Chemie & Katalyse mit BorJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Deutschland
| | - Bernd Engels
- Institut für Physikalische und Theoretische ChemieJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Deutschland
| | - Holger Braunschweig
- Institut für Anorganische ChemieJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Deutschland
- Institut für nachhaltige Chemie & Katalyse mit BorJulius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Deutschland
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49
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Devillard M, Regnier V, Pecaut J, Martin D. Stable dicationic dioxoliums and fate of their dioxolyl radicals. Org Chem Front 2019. [DOI: 10.1039/c9qo00298g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A glimpse into uncharted territory: the synthesis and study of dicationic dioxolium salts allow for assessing the fate of the corresponding elusive dioxolyl radicals.
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Affiliation(s)
| | | | - Jacques Pecaut
- Univ. Grenoble Alpes
- CEA
- CNRS
- INAC-SyMMES
- UMR 5819 38000 Grenoble
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50
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Regnier V, Romero EA, Molton F, Jazzar R, Bertrand G, Martin D. What Are the Radical Intermediates in Oxidative N-Heterocyclic Carbene Organocatalysis? J Am Chem Soc 2018; 141:1109-1117. [PMID: 30561990 DOI: 10.1021/jacs.8b11824] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The oxidation of the Breslow intermediate resulting from the addition of an N-heterocyclic carbene (NHC) to benzaldehyde triggers a fast deprotonation, followed by a second electron transfer, directly affording the corresponding acylium at E > -0.8 V (versus Fc/Fc+). Similarly, the oxidation of the cinnamaldehyde analogue occurs at an even higher potential and is not a reversible electrochemical process. As a whole, and contrary to previous beliefs, it is demonstrated that Breslow intermediates, which are the key intermediates in NHC-catalyzed transformations of aldehydes, cannot undergo a single electron transfer (SET) with mild oxidants ( E < -1.0 V). Moreover, the corresponding enol radical cations are ruled out as relevant intermediates. It is proposed that oxidative NHC-catalyzed radical transformations of enals proceed either through SET from the corresponding electron-rich enolate or through coupled electron-proton transfer from the enol, in any case generating neutral capto-dative radicals. Relevant electrochemical surrogates of these paramagnetic species have been isolated.
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Affiliation(s)
| | - Erik A Romero
- UMI CNRS 3555, Department of Chemistry and Biochemistry , University of California, San Diego , La Jolla , California 92093-0343 , United States
| | - Florian Molton
- Univ. Grenoble Alpes , CNRS, DCM , 38000 Grenoble , France
| | - Rodolphe Jazzar
- UMI CNRS 3555, Department of Chemistry and Biochemistry , University of California, San Diego , La Jolla , California 92093-0343 , United States
| | - Guy Bertrand
- UMI CNRS 3555, Department of Chemistry and Biochemistry , University of California, San Diego , La Jolla , California 92093-0343 , United States
| | - David Martin
- Univ. Grenoble Alpes , CNRS, DCM , 38000 Grenoble , France
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