1
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Das A, Elvers BJ, Chrysochos N, Uddin SI, Gangber T, Krummenacher I, Borah D, Mishra A, Shanmugam M, Yildiz CB, Braunschweig H, Schulzke C, Jana A. Dianionic and Neutral Diboron-Centered Classical Diradicaloids. J Am Chem Soc 2024; 146:9004-9011. [PMID: 38502925 DOI: 10.1021/jacs.3c13310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2024]
Abstract
Herein, we report the syntheses and electronic structures of crystalline dianionic as well as neutral diboron-centered classical diradicaloids as boron analogues of classical Thiele, Chichibabin, and Müller (this only for dianionic diradicaloids!) hydrocarbons. These are based on borane radical anion and NHC-stabilized boryl radical spin carriers, respectively. All these dianionic diboron-centered diradicaloids exhibit triplet population at room temperature regardless of the π-conjugated spacer: p-phenylene, p,p'-biphenylene, or p,p″-terphenylene. In the case of neutral diboron-centered diradicaloids, the employed π-conjugated spacer plays a crucial role for the triplet population at room temperature: EPR inactive for p-phenylene vs EPR active for p,p'-biphenylene. The findings emphasize the importance of the spin carriers for the resulting ground-state: borane radical anion vs NHC-stabilized boryl radical along with the pivotal role of the π-conjugated spacer as spin-coupler between two spins. Notably, 100 years (a century) after the first report by Krause of the triphenyl borane radical-anion, being isoelectronic to the triphenylmethyl radical, we convey borane radical anion-based diradicaloids. Furthermore, while donor-stabilized boryl radicals were introduced in the 1980s by Giles and Roberts, said concept is herewith being extended to NHC-stabilized boryl radical-based diradicaloids.
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Affiliation(s)
- Ayan Das
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, India
| | - Benedict J Elvers
- Institut für Biochemie, Universität Greifswald, Greifswald D-17489, Germany
| | - Nicolas Chrysochos
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, India
| | - Sk Imraj Uddin
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, India
| | - Tejaswinee Gangber
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, India
| | - Ivo Krummenacher
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron (ICB), Julius-Maximilians-Universität Würzburg, Am Hubland, Würzburg 97074, Germany
| | - Dipanti Borah
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India
| | - Anshika Mishra
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, India
| | - Maheswaran Shanmugam
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India
| | - Cem B Yildiz
- Department of Aromatic and Medicinal Plants, Aksaray University, Aksaray 68100, Turkey
| | - Holger Braunschweig
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron (ICB), Julius-Maximilians-Universität Würzburg, Am Hubland, Würzburg 97074, Germany
| | - Carola Schulzke
- Institut für Biochemie, Universität Greifswald, Greifswald D-17489, Germany
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, India
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2
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Abstract
Heteroatom-centered diradical(oid)s have been in the focus of molecular main group chemistry for nearly 30 years. During this time, the diradical concept has evolved and the focus has shifted to the rational design of diradical(oid)s for specific applications. This review article begins with some important theoretical considerations of the diradical and tetraradical concept. Based on these theoretical considerations, the design of diradical(oid)s in terms of ligand choice, steric, symmetry, electronic situation, element choice, and reactivity is highlighted with examples. In particular, heteroatom-centered diradical reactions are discussed and compared with closed-shell reactions such as pericyclic additions. The comparison between closed-shell reactivity, which proceeds in a concerted manner, and open-shell reactivity, which proceeds in a stepwise fashion, along with considerations of diradical(oid) design, provides a rational understanding of this interesting and unusual class of compounds. The application of diradical(oid)s, for example in small molecule activation or as molecular switches, is also highlighted. The final part of this review begins with application-related details of the spectroscopy of diradical(oid)s, followed by an update of the heteroatom-centered diradical(oid)s and tetraradical(oid)s published in the last 10 years since 2013.
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Affiliation(s)
- Alexander Hinz
- Institut für Anorganische Chemie (AOC), Karlsruher Institut für Technologie (KIT), Engesserstrasse 15, 76131 Karlsruhe, Germany
| | - Jonas Bresien
- Institut für Chemie, Universität Rostock, Albert-Einstein-Strasse 3a, 18059 Rostock, Germany
| | - Frank Breher
- Institut für Anorganische Chemie (AOC), Karlsruher Institut für Technologie (KIT), Engesserstrasse 15, 76131 Karlsruhe, Germany
| | - Axel Schulz
- Institut für Chemie, Universität Rostock, Albert-Einstein-Strasse 3a, 18059 Rostock, Germany
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3
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Fischer I, Hemberger P. Photoelectron Photoion Coincidence Spectroscopy of Biradicals. Chemphyschem 2023; 24:e202300334. [PMID: 37325876 DOI: 10.1002/cphc.202300334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 06/15/2023] [Accepted: 06/15/2023] [Indexed: 06/17/2023]
Abstract
The electronic structure of biradicals is characterized by the presence of two unpaired electrons in degenerate or near-degenerate molecular orbitals. In particular, some of the most relevant species are highly reactive, difficult to generate cleanly and can only be studied in the gas phase or in matrices. Unveiling their electronic structure is, however, of paramount interest to understand their chemistry. Photoelectron photoion coincidence (PEPICO) spectroscopy is an excellent approach to explore the electronic states of biradicals, because it enables a direct correlation between the detected ions and electrons. This permits to extract unique vibrationally resolved photoion mass-selected threshold photoelectron spectra (ms-TPES) to obtain insight in the electronic structure of both the neutral and the cation. In this review we highlight most recent advances on the spectroscopy of biradicals and biradicaloids, utilizing PEPICO spectroscopy and vacuum ultraviolet (VUV) synchrotron radiation.
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Affiliation(s)
- Ingo Fischer
- Julius-Maximilians-Universität Würzburg, Institut für Physikalische und Theoretische Chemie, Am Hubland, D-97074, Würzburg, Germany
| | - Patrick Hemberger
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institut (PSI), CH-5232, Villigen, Switzerland
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4
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Weiser J, Cui J, Dewhurst RD, Braunschweig H, Engels B, Fantuzzi F. Structure and bonding of proximity-enforced main-group dimers stabilized by a rigid naphthyridine diimine ligand. J Comput Chem 2023; 44:456-467. [PMID: 36054757 DOI: 10.1002/jcc.26994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 08/01/2022] [Accepted: 08/03/2022] [Indexed: 12/31/2022]
Abstract
The development of ligands capable of effectively stabilizing highly reactive main-group species has led to the experimental realization of a variety of systems with fascinating properties. In this work, we computationally investigate the electronic, structural, energetic, and bonding features of proximity-enforced group 13-15 homodimers stabilized by a rigid expanded pincer ligand based on the 1,8-naphthyridine (napy) core. We show that the redox-active naphthyridine diimine (NDI) ligand enables a wide variety of structural motifs and element-element interaction modes, the latter ranging from isolated, element-centered lone pairs (e.g., E = Si, Ge) to cases where through-space π bonds (E = Pb), element-element multiple bonds (E = P, As) and biradical ground states (E = N) are observed. Our results hint at the feasibility of NDI-E2 species as viable synthetic targets, highlighting the versatility and potential applications of napy-based ligands in main-group chemistry.
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Affiliation(s)
- Jonas Weiser
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Würzburg, Germany.,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Würzburg, Germany.,Institute for Physical and Theoretical Chemistry, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Jingjing Cui
- School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Wuhan, People's Republic of China
| | - Rian D Dewhurst
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Würzburg, Germany.,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Holger Braunschweig
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Würzburg, Germany.,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Bernd Engels
- Institute for Physical and Theoretical Chemistry, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Felipe Fantuzzi
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Würzburg, Germany.,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Würzburg, Germany.,School of Chemistry and Forensic Science, University of Kent, Canterbury, UK
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5
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Liu TT, Chen J, Chen XL, Ma L, Guan BT, Lin Z, Shi ZJ. Neutral Boryl Radicals in Mixed-Valent B (III) Br-B (II) Adducts. Chemistry 2023; 29:e202202634. [PMID: 36217568 DOI: 10.1002/chem.202202634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Indexed: 11/06/2022]
Abstract
The general strategies to stabilize a boryl radical involve single electron delocalization by π-system and the steric hinderance from bulky groups. Herein, a new class of boryl radicals is reported, with intramolecular mixed-valent B(III) Br-B(II) adducts ligated by a cyclic (alkyl)(amino)carbene (CAAC). The radicals feature a large spin density on the boron center, which is ascertained by EPR spectroscopy and DFT calculations. Structural and computational analyses revealed that the stability of radical species was assisted by the CAAC ligand and a weak but significant B(III)Br-B(II) interaction, suggesting a cooperative avenue for stabilization of boryl radicals. Two-electron reduction of these new boryl radicals provides C-H insertion products via a borylene intermediate.
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Affiliation(s)
- Tong-Tong Liu
- Department of Chemistry, Fudan University, Shanghai, 200438, P. R. China
| | - Jiaxin Chen
- Department of Chemistry, The Hong Kong University of Science and Technology Clear Water Bay, Kowloon, Hong Kong, P. R. China
| | - Xin-Lei Chen
- Department of Chemistry, Fudan University, Shanghai, 200438, P. R. China
| | - Li Ma
- Department of Chemistry, Fudan University, Shanghai, 200438, P. R. China
| | - Bing-Tao Guan
- Department of Chemistry, Fudan University, Shanghai, 200438, P. R. China
| | - Zhenyang Lin
- Department of Chemistry, The Hong Kong University of Science and Technology Clear Water Bay, Kowloon, Hong Kong, P. R. China
| | - Zhang-Jie Shi
- Department of Chemistry, Fudan University, Shanghai, 200438, P. R. China
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6
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Gärtner A, Meier L, Arrowsmith M, Dietz M, Krummenacher I, Bertermann R, Fantuzzi F, Braunschweig H. Highly Strained Arene-Fused 1,2-Diborete Biradicaloid. J Am Chem Soc 2022; 144:21363-21370. [DOI: 10.1021/jacs.2c09971] [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)
- Annalena Gärtner
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Lukas Meier
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Merle Arrowsmith
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Maximilian Dietz
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Ivo Krummenacher
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Rüdiger Bertermann
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Felipe Fantuzzi
- School of Chemistry and Forensic Science, University of Kent, CT2 7NH Canterbury, U.K
| | - Holger Braunschweig
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
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7
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Feng Z, Tang S, Su Y, Wang X. Recent advances in stable main group element radicals: preparation and characterization. Chem Soc Rev 2022; 51:5930-5973. [PMID: 35770612 DOI: 10.1039/d2cs00288d] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Radical species are significant in modern chemistry. Their unique chemical bonding and novel physicochemical properties play significant roles not only in fundamental chemistry, but also in materials science. Main group element radicals are usually transient due to their high reactivity. Highly stable radicals are often stabilized by π-delocalization, sterically demanding ligands, carbenes and weakly coordinating anions in recent years. This review presents the recent advances in the synthesis, characterization, reactivity and physical properties of isolable main group element radicals.
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Affiliation(s)
- Zhongtao Feng
- State Key Laboratory of Coordination Chemistry, School of Chemistry Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210023, China.
| | - Shuxuan Tang
- State Key Laboratory of Coordination Chemistry, School of Chemistry Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210023, China.
| | - Yuanting Su
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
| | - Xinping Wang
- State Key Laboratory of Coordination Chemistry, School of Chemistry Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210023, China.
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8
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Roesky HW, Kushvaha SK, Mishra A, Mondal KC. Recent advances in the domain of Cyclic (alkyl)(amino) carbenes. Chem Asian J 2022; 17:e202101301. [PMID: 34989475 PMCID: PMC9307053 DOI: 10.1002/asia.202101301] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 12/25/2021] [Indexed: 12/03/2022]
Abstract
Isolation of cyclic (alkyl) amino carbenes (cAACs) in 2005 has been a major achievement in the field of stable carbenes due to their better electronic properties. cAACs and bicyclic(alkyl)(amino)carbene (BicAAC) in essence are the most electrophilic as well as nucleophilic carbenes are known till date. Due to their excellent electronic properties in terms of nucleophilic and electrophilic character, cAACs have been utilized in different areas of chemistry, including stabilization of low valent main group and transition metal species, activation of small molecules, and catalysis. The applications of cAACs in catalysis have opened up new avenues of research in the field of cAAC chemistry. This review summarizes the major results of cAAC chemistry published until August 2021.
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Affiliation(s)
- Herbert W Roesky
- Georg-August-Universitat Gottingen, Department of Chemistry, Tammannstrasse 4, 37077, Göttingen, GERMANY
| | | | - Ankush Mishra
- IIT Madras: Indian Institute of Technology Madras, Chemistry, INDIA
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9
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Dietz M, Arrowsmith M, Gärtner A, Radacki K, Bertermann R, Braunschweig H. Harnessing the electronic differences between CAAC-stabilised 1,4-diborabenzene and 9,10-diboraanthracene for synthesis. Chem Commun (Camb) 2021; 57:13526-13529. [PMID: 34668914 DOI: 10.1039/d1cc05173c] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The oxidation of doubly cyclic alkyl(amino)carbene-stabilised closed-shell 1,4-diborabenzene with sulfur or selenium yields S4/S5- or Se4-bridged hexa-1,4-dienes, respectively, whereas that of the related open-shell singlet biradical 9,10-diboraanthracene with O2, sulfur or selenium yields the endoperoxo- or S/Se-bridged bicyclic species, respectively.
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Affiliation(s)
- Maximilian Dietz
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany. .,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Merle Arrowsmith
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany. .,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Annalena Gärtner
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany. .,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Krzysztof Radacki
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany. .,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Rüdiger Bertermann
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany. .,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Holger Braunschweig
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany. .,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
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10
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Feng Z, Chong Y, Tang S, Fang Y, Zhao Y, Jiang J, Wang X. A stable triplet diradical emitter. Chem Sci 2021; 12:15151-15156. [PMID: 34909157 PMCID: PMC8612405 DOI: 10.1039/d1sc04486a] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Accepted: 11/04/2021] [Indexed: 11/23/2022] Open
Abstract
Molecules with luminescence have been extensively investigated, but the luminescence of a stable molecule with a triplet ground state has not been observed. Synthesis of boron-containing radicals has attracted lots of interest because of their unique electronic structures and potential applications in organic semiconductors. Though some boron-based diradicals have been reported, neutral boron-containing diradicals with triplet ground states are rare. Herein two borocyclic diradicals with different substituents (3 and 4) have been isolated. Their electronic structures were investigated by EPR and UV spectroscopy, and SQUID magnetometry, in conjunction with DFT calculations. Both experiment and calculation suggest that 3 is an open shell singlet diradical while 4 is a triplet ground state diradical with a large singlet–triplet gap (0.25 kcal mol−1). Both diradicals show multi fluorescence peaks (3: 414, 431, and 470 nm; 4: 420, 433, and 495 nm). 3 displays multiple redox steps and is a potential material towards the design of high-density memory devices. 4 represents the first example of a neutral triplet boron-containing diradical with a strong ferromagnetic interaction, and also is the first stable triplet diradical emitter. Stable borocyclic diradical emitters with a tunable ground state.![]()
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Affiliation(s)
- Zhongtao Feng
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Centre of Advanced Microstructures, Nanjing University Nanjing 210023 China
| | - Yuanyuan Chong
- Hefei National Laboratory for Physical Sciences at the Microscale, CAS Center for Excellence in Nanoscience, School of Chemistry and Materials Science, University of Science and Technology of China Hefei Anhui 230026 China
| | - Shuxuan Tang
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Centre of Advanced Microstructures, Nanjing University Nanjing 210023 China
| | - Yong Fang
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Centre of Advanced Microstructures, Nanjing University Nanjing 210023 China
| | - Yue Zhao
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Centre of Advanced Microstructures, Nanjing University Nanjing 210023 China
| | - Jun Jiang
- Hefei National Laboratory for Physical Sciences at the Microscale, CAS Center for Excellence in Nanoscience, School of Chemistry and Materials Science, University of Science and Technology of China Hefei Anhui 230026 China
| | - Xinping Wang
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Centre of Advanced Microstructures, Nanjing University Nanjing 210023 China
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11
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Härterich M, Ritschel B, Arrowsmith M, Böhnke J, Krummenacher I, Phukan AK, Braunschweig H. Hybrid Inorganic-Organic Cross-Metathesis between Diborenes and Acetylene. J Am Chem Soc 2021; 143:18339-18345. [PMID: 34677063 DOI: 10.1021/jacs.1c10131] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The ruthenium-catalyzed cross-metathesis of alkenes and alkynes, which splits the alkene C═C double bond and couples one-half to each carbon of the alkyne C≡C triple bond, is one of the most efficient tools for the synthesis of 1,3-dienes, with wide-ranging applications, including pharmaceutical and polymer chemistry. In contrast, inorganic main-group metathesis reactions are restricted to a handful of examples of heavier p-block multiple bonds (P═P, Ge═Ge, and E≡E, E = Ge, Sn, Pb). We now report the first examples of thermally induced, transition-metal-free cross-metathesis between an organic alkyne and inorganic cyclic alkyl(amino)carbene (CAAC)-stabilized B═B double bonds, which yield fully planar, π-delocalized 1,8-diaza-3,6-diboraoctatetraenes. Density functional theory studies show that these compounds have an open-shell singlet biradical ground state with a thermally accessible closed-shell state. In-depth computational mechanistic analyses show that they are formed via a biradical cycloaddition-cycloreversion mechanism. Finally, unlike their organic counterparts, these B,N-analogues of octatetraene can undergo two-electron chemical reduction to form diamagnetic dianions.
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Affiliation(s)
- Marcel Härterich
- Institute of Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, 97074 Würzburg, Germany.,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, 97074 Würzburg, Germany
| | - Benedikt Ritschel
- Institute of Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, 97074 Würzburg, Germany.,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, 97074 Würzburg, Germany
| | - Merle Arrowsmith
- Institute of Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, 97074 Würzburg, Germany.,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, 97074 Würzburg, Germany
| | - Julian Böhnke
- Institute of Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, 97074 Würzburg, Germany.,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, 97074 Würzburg, Germany
| | - Ivo Krummenacher
- Institute of Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, 97074 Würzburg, Germany.,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, 97074 Würzburg, Germany
| | - Ashwini K Phukan
- Department of Chemical Sciences, Tezpur University, Tezpur 784028, Assam, India
| | - Holger Braunschweig
- Institute of Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, 97074 Würzburg, Germany.,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, 97074 Würzburg, Germany
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12
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Abstract
Boron-centred radicals (boryl radicals) are potential and attractive species in main group chemistry and synthetic chemistry. Recently, the development of boron compounds ligated by N-heterocyclic carbenes (NHCs) has sparked off advavnces in boryl radical chemistry because NHCs can highly stabilise boryl radicals by electronic and steric factors. This review highlights recent synthesis and reactions of such NHC-boryl radicals. From the standpoint of main group chemistry, examples of isolation or detection of unique NHC-boryl radicals are presented. From the standpoint of synthetic chemistry, on the other hand, the development of reactions of user-friendly NHC-boryl radicals, which has contributed to radical chemistry, organoboron chemistry and polymer science, is comprehensively described.
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Affiliation(s)
- Tsuyoshi Taniguchi
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
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13
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Ress L, Kaiser D, Grüne J, Gerlach M, Reusch E, Brixner T, Sperlich A, Engels B, Fischer I. Femtosecond dynamics of diphenylpropynylidene in ethanol and dichloromethane. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 254:119606. [PMID: 33740753 DOI: 10.1016/j.saa.2021.119606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 02/02/2021] [Accepted: 02/05/2021] [Indexed: 06/12/2023]
Abstract
Carbon chains with an odd number of C atoms are reactive intermediates with a high biradical character. Here we report a joint experimental and computational investigation of the dynamics of diphenylpropynylidene, C6H5-C3-C6H5, in dichloromethane and ethanol. The biradical is generated by ultraviolet light from 1,3-diphenyldiazopropyne. Electron paramagnetic resonance spectra are recorded to elucidate the spin multiplicity and geometry of the biradical. In both solvents a triplet ground state at 4 K is verified. Transient absorption spectra provide insight into the fate of the biradical. A study in deaerated dichloromethane permits us to follow the photophysics of diphenylpropynylidene and to extract time constants for its vibrational as well as electronic relaxation. In the presence of oxygen, a more complex photochemistry is observed that permits us to derive a model for the reaction of the biradical with O2. In ethanol, the spectra recorded in the presence and absence of O2 are very similar, which can be explained by the similarity of the chromophores of the reaction products.
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Affiliation(s)
- Lea Ress
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Dustin Kaiser
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Jeannine Grüne
- Fakultät für Physik, Universität of Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Marius Gerlach
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Engelbert Reusch
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Tobias Brixner
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany; Center for Nanosystems Chemistry (CNC), Universität Würzburg, Theodor-Boveri-Weg, 97074 Würzburg, Germany.
| | - Andreas Sperlich
- Fakultät für Physik, Universität of Würzburg, Am Hubland, D-97074 Würzburg, Germany.
| | - Bernd Engels
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
| | - Ingo Fischer
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
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14
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Maiti A, Zhang F, Krummenacher I, Bhattacharyya M, Mehta S, Moos M, Lambert C, Engels B, Mondal A, Braunschweig H, Ravat P, Jana A. Anionic Boron- and Carbon-Based Hetero-Diradicaloids Spanned by a p-Phenylene Bridge. J Am Chem Soc 2021; 143:3687-3692. [PMID: 33651600 DOI: 10.1021/jacs.0c12624] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Herein we report the synthesis and characterization of anionic boron- and carbon-based Kekulé diradicaloids spanned by a p-phenylene bridge. In contrast to Thiele's hydrocarbon, a closed-shell singlet system, they show an appreciable population of the triplet state at room temperature, as evidenced by both NMR and EPR spectroscopy. Moreover, en route to these anionic boron- and carbon-based hetero-diradicaloids, the formation of an isolable diamino(4-diarylboryl-phenyl)methyl radical was observed.
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Affiliation(s)
- Avijit Maiti
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad-500046, India
| | - Fangyuan Zhang
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Ivo Krummenacher
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron (ICB), Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Moulika Bhattacharyya
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad-500046, India
| | - Sakshi Mehta
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
| | - Michael Moos
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Christoph Lambert
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Bernd Engels
- Institut für Physikalische und Theoretische Chemie, Julius-Maximilians-Universität Würzburg, Emil-Fischer-Strasse 42, 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 (ICB), Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, 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-500046, India
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15
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Schmid P, Fantuzzi F, Klopf J, Schröder NB, Dewhurst RD, Braunschweig H, Engel V, Engels B. Twisting versus Delocalization in CAAC- and NHC-Stabilized Boron-Based Biradicals: The Roles of Sterics and Electronics. Chemistry 2021; 27:5160-5170. [PMID: 33225473 PMCID: PMC8048672 DOI: 10.1002/chem.202004619] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 11/12/2020] [Indexed: 11/06/2022]
Abstract
Twisted boron-based biradicals featuring unsaturated C2 R2 (R=Et, Me) bridges and stabilization by cyclic (alkyl)(amino)carbenes (CAACs) were recently prepared. These species show remarkable geometrical and electronic differences with respect to their unbridged counterparts. Herein, a thorough computational investigation on the origin of their distinct electrostructural properties is performed. It is shown that steric effects are mostly responsible for the preference for twisted over planar structures. The ground-state multiplicity of the twisted structure is modulated by the σ framework of the bridge, and different R groups lead to distinct multiplicities. In line with the experimental data, a planar structure driven by delocalization effects is observed as global minimum for R=H. The synthetic elusiveness of C2 R2 -bridged systems featuring N-heterocyclic carbenes (NHCs) was also investigated. These results could contribute to the engineering of novel main group biradicals.
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Affiliation(s)
- Paul Schmid
- Institute for Physical and Theoretical ChemistryJulius-Maximilians-Universität WürzburgEmil-Fischer-Strasse 4297074WürzburgGermany
| | - Felipe Fantuzzi
- Institute for Physical and Theoretical ChemistryJulius-Maximilians-Universität WürzburgEmil-Fischer-Strasse 4297074WürzburgGermany
- Institute for Inorganic ChemistryJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
- Institute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Jonas Klopf
- Institute for Physical and Theoretical ChemistryJulius-Maximilians-Universität WürzburgEmil-Fischer-Strasse 4297074WürzburgGermany
| | - Niklas B. Schröder
- Institute for Physical and Theoretical ChemistryJulius-Maximilians-Universität WürzburgEmil-Fischer-Strasse 4297074WürzburgGermany
| | - Rian D. Dewhurst
- Institute for Inorganic ChemistryJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
- Institute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Holger Braunschweig
- Institute for Inorganic ChemistryJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
- Institute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Volker Engel
- Institute for Physical and Theoretical ChemistryJulius-Maximilians-Universität WürzburgEmil-Fischer-Strasse 4297074WürzburgGermany
| | - Bernd Engels
- Institute for Physical and Theoretical ChemistryJulius-Maximilians-Universität WürzburgEmil-Fischer-Strasse 4297074WürzburgGermany
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16
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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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17
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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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18
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Feng Z, Fang Y, Ruan H, Zhao Y, Tan G, Wang X. Stable Radical Cation and Dication of an N‐Heterocyclic Carbene Stabilized Digallene: Synthesis, Characterization and Reactivity. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202000051] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Zhongtao Feng
- State Key Laboratory of Coordination ChemistryJiangsu Key Laboratory of Advanced Organic MaterialsSchool of Chemistry and Chemical EngineeringCollaborative Innovation Center of Advanced MicrostructuresNanjing University Nanjing 210023 P. R. China
| | - Yong Fang
- State Key Laboratory of Coordination ChemistryJiangsu Key Laboratory of Advanced Organic MaterialsSchool of Chemistry and Chemical EngineeringCollaborative Innovation Center of Advanced MicrostructuresNanjing University Nanjing 210023 P. R. China
| | - Huapeng Ruan
- State Key Laboratory of Coordination ChemistryJiangsu Key Laboratory of Advanced Organic MaterialsSchool of Chemistry and Chemical EngineeringCollaborative Innovation Center of Advanced MicrostructuresNanjing University Nanjing 210023 P. R. China
| | - Yue Zhao
- State Key Laboratory of Coordination ChemistryJiangsu Key Laboratory of Advanced Organic MaterialsSchool of Chemistry and Chemical EngineeringCollaborative Innovation Center of Advanced MicrostructuresNanjing University Nanjing 210023 P. R. China
| | - Gengwen Tan
- State Key Laboratory of Coordination ChemistryJiangsu Key Laboratory of Advanced Organic MaterialsSchool of Chemistry and Chemical EngineeringCollaborative Innovation Center of Advanced MicrostructuresNanjing University Nanjing 210023 P. R. China
- College of Chemistry, Chemical Engineering and Materials ScienceSoochow University Suzhou 215123 P. R. China
| | - Xinping Wang
- State Key Laboratory of Coordination ChemistryJiangsu Key Laboratory of Advanced Organic MaterialsSchool of Chemistry and Chemical EngineeringCollaborative Innovation Center of Advanced MicrostructuresNanjing University Nanjing 210023 P. R. China
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19
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Feng Z, Fang Y, Ruan H, Zhao Y, Tan G, Wang X. Stable Radical Cation and Dication of an N-Heterocyclic Carbene Stabilized Digallene: Synthesis, Characterization and Reactivity. Angew Chem Int Ed Engl 2020; 59:6769-6774. [PMID: 31994317 DOI: 10.1002/anie.202000051] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Indexed: 11/06/2022]
Abstract
One- and two-electron oxidation of a digallene stabilized by an N-heterocyclic carbene afforded the first stable gallium-based radical cation and dication salts, respectively. Structural analysis and theoretical calculations reveal that the oxidation occurs at the Ga=Ga double bond, leading to removal of π electrons of the double bond and a decrease of the bond order. The spin density of the radical cation mainly locates at the two gallium centers as demonstrated by EPR spectroscopy and theoretical calculations. Moreover, the reactivity of the radical cation salt toward nBu3 SnH and cyclo-S8 was studied; a digallium-hydride cation salt containing a Ga-Ga single bond and a gallium sulfide cluster bearing an unprecedented ladder-like Ga4 S4 core structure were obtained, respectively.
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Affiliation(s)
- Zhongtao Feng
- 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, P. R. China
| | - Yong Fang
- 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, P. R. China
| | - Huapeng Ruan
- 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, P. R. 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, P. R. China
| | - Gengwen Tan
- 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, P. R. China.,College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, P. R. 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, P. R. China
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20
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Kobayashi A, Suzuki K, Kitamura R, Yamashita M. Formation of BCBH/BCBCl Four-Membered Rings by Complexation of Boron- and Nitrogen-Substituted Acetylene with Hydro-/Chloroboranes. Organometallics 2020. [DOI: 10.1021/acs.organomet.9b00876] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Akemi Kobayashi
- Department of Molecular and Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Katsunori Suzuki
- Department of Molecular and Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Ryo Kitamura
- Department of Applied Chemistry, Graduate School of Science and Engineering, Chuo University, Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan
| | - Makoto Yamashita
- Department of Molecular and Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
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21
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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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22
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Hagspiel S, Arrowsmith M, Fantuzzi F, Hermann A, Paprocki V, Drescher R, Krummenacher I, Braunschweig H. Reduction of a dihydroboryl cation to a boryl anion and its air-stable, neutral hydroboryl radical through hydrogen shuttling. Chem Sci 2019; 11:551-555. [PMID: 32206272 PMCID: PMC7069503 DOI: 10.1039/c9sc05026d] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 11/23/2019] [Indexed: 02/05/2023] Open
Abstract
A doubly cyclic (alkyl)(amino)carbene-stabilised dihydroboronium cation undergoes fully reversible 2e– reduction to a stable hydroboryl anion via B-to-C hydrogen migration. Subsequent 1e– oxidation yields a bench-stable neutral hydroboryl radical.
The addition of Lewis bases to a cyclic (alkyl)(amino)carbene (CAAC)-supported dihydroboron triflate yields the mixed doubly base-stabilised dihydroboryl cations [(CAAC)BH2L]+. Of these, [(CAAC)2BH2]OTf (OTf = triflate) underwent facile two-electron reduction with KC8 owing to a 1,2-hydride migration from boron to the carbene carbon to yield a stable hydroboryl anion. One-electron oxidation of the latter yielded the first neutral hydroboryl radical, which is bench-stable in the solid state.
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Affiliation(s)
- Stephan Hagspiel
- Institut für Anorganische Chemie , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany . .,Institute for Sustainable Chemistry & Catalysis with Boron , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany
| | - Merle Arrowsmith
- Institut für Anorganische Chemie , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany . .,Institute for Sustainable Chemistry & Catalysis with Boron , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany
| | - Felipe Fantuzzi
- Institut für Anorganische Chemie , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany . .,Institute for Sustainable Chemistry & Catalysis with Boron , 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
| | - Alexander Hermann
- Institut für Anorganische Chemie , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany . .,Institute for Sustainable Chemistry & Catalysis with Boron , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany
| | - Valerie Paprocki
- Institut für Anorganische Chemie , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany . .,Institute for Sustainable Chemistry & Catalysis with Boron , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany
| | - Regina Drescher
- Institut für Anorganische Chemie , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany . .,Institute for Sustainable Chemistry & Catalysis with Boron , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany
| | - Ivo Krummenacher
- Institut für Anorganische Chemie , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany . .,Institute for Sustainable Chemistry & Catalysis with Boron , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany
| | - Holger Braunschweig
- Institut für Anorganische Chemie , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany . .,Institute for Sustainable Chemistry & Catalysis with Boron , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany
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23
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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: 89] [Impact Index Per Article: 17.8] [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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24
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Feng R, Yang W, Wang W, Zhao Y, Tan G, Zhang L, Wang X. Isolable diboryl radicals acting as highly efficient reaction intermediates under mild conditions. Chem Commun (Camb) 2019; 55:12908-12911. [DOI: 10.1039/c9cc06514h] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Activation of the B–B bond in diborane with dimesitylpyridyl boranes afforded the stable diboryl radicals in moderate yields.
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Affiliation(s)
- Rui Feng
- State Key Laboratory of Coordination Chemistry
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023
- China
| | - Wenbang Yang
- State Key Laboratory of Coordination Chemistry
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023
- China
| | - Wenqing Wang
- 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
| | - Gengwen Tan
- State Key Laboratory of Coordination Chemistry
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023
- China
| | - Li Zhang
- State Key Laboratory of Coordination Chemistry
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023
- China
| | - Xinping Wang
- State Key Laboratory of Coordination Chemistry
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023
- China
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