1
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Hollister KK, Molino A, Jones N, Le VV, Dickie DA, Cafiso DS, Wilson DJD, Gilliard RJ. Unlocking Biradical Character in Diborepins. J Am Chem Soc 2024; 146:6506-6515. [PMID: 38420913 DOI: 10.1021/jacs.3c08297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2024]
Abstract
Systems that possess open- and closed-shell behavior attract significant attention from researchers due to their inherent redox and charge transport properties. Herein, we report the synthesis of the first diborepin biradicals. They display tunable biradical character based on the steric and electronic profile of the stabilizing ligand and the resulting geometric deviation of the diborepin core from planarity. While there are numerous all-carbon-based biradical systems, boron-based biradical compounds are comparatively rare, particularly ones in which the radical sites are disjointed. Calculations using density functional theory (DFT) and multireference methods demonstrate that the fused diborepin scaffold exhibits high biradical character, up to 95%. Use of a nonsterically demanding diaminocarbene promotes the planarization of the pentacyclic framework, resulting in the synthetic realization of a diborepin containing a dibora-quinoidal core, which possesses a closed-shell ground state and thermally accessible triplet state. The biradicals were structurally authenticated and characterized by both solution and solid-state electron paramagnetic resonance (EPR) spectroscopy. Half-field transitions were observed at low temperatures (about 170 K), confirming the presence of the triplet state. Initial reactivity studies of the biradicals led to the isolation and structural characterization of bis(borepin hydride) and bis(borepin dianion).
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Affiliation(s)
- Kimberly K Hollister
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Building 18-596, Cambridge, Massachusetts 02139-4307, United States
| | - Andrew Molino
- Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne 3086, Victoria, Australia
| | - Nula Jones
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
| | - VuongVy V Le
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Diane A Dickie
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
| | - David S Cafiso
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
| | - David J D Wilson
- Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne 3086, Victoria, Australia
| | - Robert J Gilliard
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Building 18-596, Cambridge, Massachusetts 02139-4307, United States
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2
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Sun C, Liu Q, Meng L, Li X. Small molecules (CO 2 , iPrNCO, and iPrNCNiPr) activation by the metallomimetics (μ-Hydrido) diborane anion: A DFT investigation on mechanism and chemoselectivity controlling. J Comput Chem 2024; 45:331-340. [PMID: 37846101 DOI: 10.1002/jcc.27240] [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: 08/18/2023] [Revised: 09/27/2023] [Accepted: 09/28/2023] [Indexed: 10/18/2023]
Abstract
Main-group metallomimetics provide a new way to replace transition metal complexes to activate inert small molecules under mild conditions. In this work, the activation mechanisms of CO2 , iPrNCO, and iPrNCNiPr by (μ-Hydrido) diborane anion ([1H]- ) have been investigated by density functional theory (DFT) calculations. Two different activation sites, BB versus BH bond of [1H]- , are investigated and compared. The results show that these inert molecules can be activated by [1H]- through cycloadditions under mild conditions. The reactions with iPrNCO and iPrNCNiPr are dynamic and thermodynamic controlling, the obtained products are related not only to the energy barrier but also to the stability of the products. Moreover, the competition for BB/BH bond site activation is directly related to the steric effect of small molecules. CO2 , which is without steric hindrance, can only be activated by the BB bond, whereas iPrNCNiPr can only be activated by the BH bond due to the large steric effect. The medium iPrNCO can be activated not only by the BB bond but also by the BH bond. Our study provides theoretical explanations for the reaction activity and chemoselectivity controlling of the title reaction, and displays the potential applications for compounds containing boron-boron bonds and inert small molecule activation.
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Affiliation(s)
- ChenFei Sun
- College of Chemistry and Material Science, Hebei Key Laboratory of Inorganic and Nano-Materials, Hebei Normal University, Shijiazhuang, China
| | - Qing Liu
- College of Chemistry and Material Science, Hebei Key Laboratory of Inorganic and Nano-Materials, Hebei Normal University, Shijiazhuang, China
| | - Lingpeng Meng
- College of Chemistry and Material Science, Hebei Key Laboratory of Inorganic and Nano-Materials, Hebei Normal University, Shijiazhuang, China
| | - Xiaoyan Li
- College of Chemistry and Material Science, Hebei Key Laboratory of Inorganic and Nano-Materials, Hebei Normal University, Shijiazhuang, China
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3
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Ahmad A, Gayen S, Mishra S, Afsan Z, Bontemps S, Ghosh S. Doubly Base-Stabilized Diborane(4) and Borato-Boronium Species and Their Chemistry with Chalcogens. Inorg Chem 2024; 63:3376-3382. [PMID: 38329931 DOI: 10.1021/acs.inorgchem.3c03961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
In an effort to isolate diborane(4) derivatives, we have developed an efficient and uncatalyzed approach using [BH3·THF] and the mercaptopyridine ligand. Thermolysis of 2-mercaptopyridine, in the presence of [BH3·THF], afforded a doubly base-stabilized diborane(4) species 1, [HB(μ-C5H4NS)]2, along with the formation of its isomeric species 2, [HB(μ-C5H4NS)]2, albeit in less yield. Based on the coordination of the boron with the mercaptopyridine ligand in 2 and its spectroscopic data, compound 2 has been designated as a borato-boronium species, in which the anionic borate and cationic boronium units are covalently bonded to each other. Furthermore, we have demonstrated the oxidative insertion of chalcogen atoms (S and Se) through the B-B bond of the base-stabilized diborane(4), 1, that yielded chalcogenido-diboron species, 3(S) and 4(Se).
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Affiliation(s)
- Asif Ahmad
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India
| | - Sourav Gayen
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India
| | - Shivankan Mishra
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India
| | - Zeenat Afsan
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India
| | - Sébastien Bontemps
- LCC-CNRS, Université de Toulouse, CNRS, 205 route de Narbonne, Toulouse 31077, Cedex 04, France
| | - Sundargopal Ghosh
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India
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4
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Gilmer J, Bolte M, Virovets A, Lerner HW, Fantuzzi F, Wagner M. A Hydride-Substituted Homoleptic Silylborate: How Similar is it to its Diborane(6)-Dianion Isostere? Chemistry 2023; 29:e202203119. [PMID: 36210643 PMCID: PMC10100083 DOI: 10.1002/chem.202203119] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Indexed: 11/05/2022]
Abstract
The B-nucleophilic 9H-9-borafluorene dianion reacts with 9-chloro-9-silafluorene to afford air- and moisture-stable silylborate salts M[Ar2 (H)B-Si(H)Ar2 ] (M[HBSiH], M=Li, Na). Li[HBSiH] and Me3 SiCl give the B-pyridine adduct Ar2 (py)B-Si(H)Ar2 ((py)BSiH) or the chlorosilane Li[Ar2 (H)B-Si(Cl)Ar2 ] (Li[HBSiCl]) in C6 H6 -pyridine or THF. In both cases, the first step is H- abstraction at the B center. The resulting free borane subsequently binds a py or thf ligand. While the py adduct is stable at room temperature, the thf adduct undergoes a 1,2-H shift via the cyclic B(μ-H)Si intermediate BHSi, which is afterwards attacked at the Si atom by a Cl- ion to give Li[HBSiCl]. DFT calculations were employed to support the proposed reaction mechanism and to characterize the electronic structure of BHSi. Treatment of Li[HBSiCl] with the N-heterocyclic carbene IMe introduces the neutral donor at the Si atom and leads to Ar2 (H)B-Si(IMe)Ar2 (HBSi(IMe)), a donor-acceptor-stabilized silylene.
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Affiliation(s)
- Jannik Gilmer
- Institut für Anorganische und Analytische Chemie, J. W. Goethe-Universität Frankfurt, Max-von-Laue-Str. 7, 60438, Frankfurt (Main), Germany
| | - Michael Bolte
- Institut für Anorganische und Analytische Chemie, J. W. Goethe-Universität Frankfurt, Max-von-Laue-Str. 7, 60438, Frankfurt (Main), Germany
| | - Alexander Virovets
- Institut für Anorganische und Analytische Chemie, J. W. Goethe-Universität Frankfurt, Max-von-Laue-Str. 7, 60438, Frankfurt (Main), Germany
| | - Hans-Wolfram Lerner
- Institut für Anorganische und Analytische Chemie, J. W. Goethe-Universität Frankfurt, Max-von-Laue-Str. 7, 60438, Frankfurt (Main), Germany
| | - Felipe Fantuzzi
- School of Chemistry and Forensic Science, University of Kent, Park Wood Rd, Canterbury, CT2 7NH, UK
| | - Matthias Wagner
- Institut für Anorganische und Analytische Chemie, J. W. Goethe-Universität Frankfurt, Max-von-Laue-Str. 7, 60438, Frankfurt (Main), Germany
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5
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Chen C, Wang MW, Zhao XY, Yang S, Chen XY, Wang XY. Pushing the Length Limit of Dihydrodiboraacenes: Synthesis and Characterizations of Boron-Embedded Heptacene and Nonacene. Angew Chem Int Ed Engl 2022; 61:e202200779. [PMID: 35253330 DOI: 10.1002/anie.202200779] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Indexed: 12/24/2022]
Abstract
Boron-embedded heteroacenes (boraacenes) have attracted enormous interest in organic chemistry and materials science. However, extending the skeleton of boraacenes to higher acenes (N≥6) is synthetically challenging because of their limited stability under ambient conditions. Herein, we report the synthesis of boron-embedded heptacene (DBH) and nonacene (DBN) as the hitherto longest boraacenes. The former is highly stable (even after 240 h in tetrahydrofuran), while the latter is air-sensitive with the half-life (t1/2 ) of 11.8 min. The structures of both compounds are verified by single-crystal X-ray diffraction, revealing a linear backbone with an antiaromatic C4 B2 core. Photophysical characterizations associated with theoretical calculations indicate that both compounds exhibit highly efficient anti-Kasha emissions. Remarkably, the air-stable DBH manifests an ultrahigh photoluminescence quantum yield (PLQY) of 98±2 % and can be chemically reduced to its radical anion and dianion states, implying the value of boron-doped higher acenes as novel functional materials.
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Affiliation(s)
- Cheng Chen
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, China
| | - Ming-Wei Wang
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, China
| | - Xing-Yu Zhao
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, China
| | - Shuang Yang
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, China
| | - Xing-Yu Chen
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, China
| | - Xiao-Ye Wang
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, China
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6
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Chen C, Wang M, Zhao X, Yang S, Chen X, Wang X. Pushing the Length Limit of Dihydrodiboraacenes: Synthesis and Characterizations of Boron‐Embedded Heptacene and Nonacene. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202200779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Cheng Chen
- State Key Laboratory of Elemento-Organic Chemistry College of Chemistry Nankai University Tianjin 300071 China
| | - Ming‐Wei Wang
- State Key Laboratory of Elemento-Organic Chemistry College of Chemistry Nankai University Tianjin 300071 China
| | - Xing‐Yu Zhao
- State Key Laboratory of Elemento-Organic Chemistry College of Chemistry Nankai University Tianjin 300071 China
| | - Shuang Yang
- State Key Laboratory of Elemento-Organic Chemistry College of Chemistry Nankai University Tianjin 300071 China
| | - Xing‐Yu Chen
- State Key Laboratory of Elemento-Organic Chemistry College of Chemistry Nankai University Tianjin 300071 China
| | - Xiao‐Ye Wang
- State Key Laboratory of Elemento-Organic Chemistry College of Chemistry Nankai University Tianjin 300071 China
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7
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Chen C, Daniliuc CG, Kehr G, Erker G. Formation and Cycloaddition Reactions of a Reactive Boraalkene Stabilized Internally by N-Heterocyclic Carbene. Angew Chem Int Ed Engl 2021; 60:19905-19911. [PMID: 34219331 DOI: 10.1002/anie.202106724] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 06/28/2021] [Indexed: 01/07/2023]
Abstract
The synthesis of element-carbon double bonds is of great importance for the development and understanding of reactive π-bonded systems in chemistry. The seven-membered heterocyclic system 4 b is readily made by internal C-H activation at a pendent isopropyl methyl group of the respective [(IPr)C6 F5 BH]+ borenium ion. Subsequent deprotonation with the IMes carbene gives the neutral cyclic boraalkene system 5 b. The B=C double bond in compound 5 b adds carbon dioxide, CS2 , sulfur dioxide, phenyl isocyanate, an acetylenic ester or two NO molecules to give the corresponding four-membered ring annulated heterocycles. With sulfur or selenium 5 b gives the respective three-membered ring systems. N2 O reacts with 5 b to give a mixture of the related oxaborirane 18 and a unique [B]OH containing diazoalkane product 19.
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Affiliation(s)
- Chaohuang Chen
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149, Münster, Germany
| | - Constantin G Daniliuc
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149, Münster, Germany
| | - Gerald Kehr
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149, Münster, Germany
| | - Gerhard Erker
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149, Münster, Germany
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8
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Budy H, Kaese T, Bolte M, Lerner H, Wagner M. A Chemiluminescent Tetraaryl Diborane(4) Tetraanion. Angew Chem Int Ed Engl 2021; 60:19397-19405. [PMID: 34161639 PMCID: PMC8456833 DOI: 10.1002/anie.202106980] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 06/22/2021] [Indexed: 12/13/2022]
Abstract
Two subvalent, redox-active diborane(4) anions, [3]4- and [3]2- , carrying exceptionally high negative charge densities are reported: Reduction of 9-methoxy-9-borafluorene with Li granules without stirring leads to the crystallization of the B(sp3 )-B(sp2 ) diborane(5) anion salt Li[5]. [5]- contains a 2,2'-biphenyldiyl-bridged B-B core, a chelating 2,2'-biphenyldiyl moiety, and a MeO substituent. Reduction of Li[5] with Na metal gives the Na+ salt of the tetraanion [3]4- in which two doubly reduced 9-borafluorenyl fragments are linked via a B-B single bond. Comproportionation of Li[5] and Na4 [3] quantitatively furnishes the diborane(4) dianion salt Na2 [3], the doubly boron-doped congener of 9,9'-bis(fluorenylidene). Under acid catalysis, Na2 [3] undergoes a formal Stone-Wales rearrangement to yield a dibenzo[g,p]chrysene derivative with B=B core. Na2 [3] shows boron-centered nucleophilicity toward n-butyl chloride. Na4 [3] produces bright blue chemiluminescence when exposed to air.
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Affiliation(s)
- Hendrik Budy
- Institut für Anorganische ChemieGoethe-Universität FrankfurtMax-von-Laue-Strasse 760438Frankfurt (Main)Germany
| | - Thomas Kaese
- Institut für Anorganische ChemieGoethe-Universität FrankfurtMax-von-Laue-Strasse 760438Frankfurt (Main)Germany
| | - Michael Bolte
- Institut für Anorganische ChemieGoethe-Universität FrankfurtMax-von-Laue-Strasse 760438Frankfurt (Main)Germany
| | - Hans‐Wolfram Lerner
- Institut für Anorganische ChemieGoethe-Universität FrankfurtMax-von-Laue-Strasse 760438Frankfurt (Main)Germany
| | - Matthias Wagner
- Institut für Anorganische ChemieGoethe-Universität FrankfurtMax-von-Laue-Strasse 760438Frankfurt (Main)Germany
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9
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Chen C, Daniliuc CG, Kehr G, Erker G. Formation and Cycloaddition Reactions of a Reactive Boraalkene Stabilized Internally by
N
‐Heterocyclic Carbene. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202106724] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Chaohuang Chen
- Organisch-Chemisches Institut Westfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Germany
| | - Constantin G. Daniliuc
- Organisch-Chemisches Institut Westfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Germany
| | - Gerald Kehr
- Organisch-Chemisches Institut Westfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Germany
| | - Gerhard Erker
- Organisch-Chemisches Institut Westfälische Wilhelms-Universität Münster Corrensstraße 40 48149 Münster Germany
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10
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Budy H, Kaese T, Bolte M, Lerner H, Wagner M. A Chemiluminescent Tetraaryl Diborane(4) Tetraanion. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202106980] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Hendrik Budy
- Institut für Anorganische Chemie Goethe-Universität Frankfurt Max-von-Laue-Strasse 7 60438 Frankfurt (Main) Germany
| | - Thomas Kaese
- Institut für Anorganische Chemie Goethe-Universität Frankfurt Max-von-Laue-Strasse 7 60438 Frankfurt (Main) Germany
| | - Michael Bolte
- Institut für Anorganische Chemie Goethe-Universität Frankfurt Max-von-Laue-Strasse 7 60438 Frankfurt (Main) Germany
| | - Hans‐Wolfram Lerner
- Institut für Anorganische Chemie Goethe-Universität Frankfurt Max-von-Laue-Strasse 7 60438 Frankfurt (Main) Germany
| | - Matthias Wagner
- Institut für Anorganische Chemie Goethe-Universität Frankfurt Max-von-Laue-Strasse 7 60438 Frankfurt (Main) Germany
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11
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Trageser T, Bebej D, Bolte M, Lerner HW, Wagner M. B-B vs. B-H Bond Activation in a (μ-Hydrido)diborane(4) Anion upon Cycloaddition with CO 2 , Isocyanates, or Carbodiimides. Angew Chem Int Ed Engl 2021; 60:13500-13506. [PMID: 33740318 PMCID: PMC8252796 DOI: 10.1002/anie.202103427] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Indexed: 11/11/2022]
Abstract
The intriguing (μ‐hydrido)diboranes(4) with their prominent pristine representative [B2H5]− have mainly been studied theoretically. We now describe the behavior of the planarized tetraaryl (μ‐hydrido)diborane(4) anion [1H]− in cycloaddition reactions with the homologous series of heterocumulenes CO2, iPrNCO, and iPrNCNiPr. We show that a C=O bond of CO2 selectively activates the B−B bond of [1H]−, while the μ‐H ligand is left untouched ([2H]−). The carbodiimide iPrNCNiPr, in contrast, neglects the B−B bond and rather adds the B‐bonded H− ion to its central C atom to generate a formamidinate bridge across the B2 pair ([3]−). As a hybrid, the isocyanate iPrNCO combines the reactivity patterns of both its congeners and gives two products: one of them ([4H]−) is related to [2H]−, the other ([5]−) is an analog of [3]−. We finally propose a mechanistic scenario that rationalizes the individual reaction outcomes and combines them to a coherent picture of B–B vs. B–H bond activation.
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Affiliation(s)
- Timo Trageser
- Institut für Anorganische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Strasse 7, 60438, Frankfurt (Main), Germany
| | - Dariusz Bebej
- Institut für Anorganische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Strasse 7, 60438, Frankfurt (Main), Germany
| | - Michael Bolte
- Institut für Anorganische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Strasse 7, 60438, Frankfurt (Main), Germany
| | - Hans-Wolfram Lerner
- Institut für Anorganische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Strasse 7, 60438, Frankfurt (Main), Germany
| | - Matthias Wagner
- Institut für Anorganische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Strasse 7, 60438, Frankfurt (Main), Germany
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