1
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Wentz KE, Molino A, Freeman LA, Dickie DA, Wilson DJD, Gilliard RJ. Approaching Dianionic Tetraoxadiborecine Macrocycles: 10-Membered Bora-Crown Ethers Incorporating Borafluorenate Units. Angew Chem Int Ed Engl 2023; 62:e202215772. [PMID: 36437238 DOI: 10.1002/anie.202215772] [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: 10/26/2022] [Revised: 11/24/2022] [Accepted: 11/25/2022] [Indexed: 11/29/2022]
Abstract
The addition of non-benzenoid quinones, acenapthenequinone or aceanthrenequinone, to the 9-carbene-9-borafluorene monoanion (1) affords the first examples of dianionic 10-membered bora-crown ethers (2-5), which are characterized by multi-nuclear NMR spectroscopy (1 H, 13 C, 11 B), X-ray crystallography, elemental analysis, and UV/Vis spectroscopy. These tetraoxadiborecines have distinct absorption profiles based on the positioning of the alkali metal cations. When compound 4, which has a vacant C4 B2 O4 cavity, is reacted with sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, a color change from purple to orange serves as a visual indicator of metal binding to the central ring, whereby the Na+ ion coordinates to four oxygen atoms. A detailed theoretical analysis of the calculated reaction energetics is provided to gain insight into the reaction mechanism for the formation of 2-5. These data, and the electronic structures of proposed intermediates, indicate that the reaction proceeds via a boron enolate intermediate.
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Affiliation(s)
- Kelsie E Wentz
- Department of Chemistry, University of Virginia, 409 McCormick Rd./PO Box 400319, 22904, Charlottesville, VA, USA
| | - Andrew Molino
- Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, 3086, Melbourne, Victoria, Australia
| | - Lucas A Freeman
- Department of Chemistry, University of Virginia, 409 McCormick Rd./PO Box 400319, 22904, Charlottesville, VA, USA
| | - Diane A Dickie
- Department of Chemistry, University of Virginia, 409 McCormick Rd./PO Box 400319, 22904, Charlottesville, VA, USA
| | - David J D Wilson
- Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, 3086, Melbourne, Victoria, Australia
| | - Robert J Gilliard
- Department of Chemistry, University of Virginia, 409 McCormick Rd./PO Box 400319, 22904, Charlottesville, VA, USA
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2
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Zhang C, Wang J, Lin Z, Ye Q. Synthesis, Characterization, and Properties of Three-Dimensional Analogues of 9-Borafluorenes. Inorg Chem 2022; 61:18275-18284. [DOI: 10.1021/acs.inorgchem.2c03111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Chonghe Zhang
- Department of Chemistry, Southern University of Science and Technology, 518055 Shenzhen, P. R. China
| | - Junyi Wang
- Department of Chemistry, Southern University of Science and Technology, 518055 Shenzhen, P. R. China
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, 999077 Kowloon, Hong Kong
| | - Zhenyang Lin
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, 999077 Kowloon, Hong Kong
| | - Qing Ye
- 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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3
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Hollister KK, Yang W, Mondol R, Wentz KE, Molino A, Kaur A, Dickie DA, Frenking G, Pan S, Wilson DJD, Gilliard RJ. Isolation of Stable Borepin Radicals and Anions. Angew Chem Int Ed Engl 2022; 61:e202202516. [PMID: 35289046 PMCID: PMC9324096 DOI: 10.1002/anie.202202516] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Indexed: 12/31/2022]
Abstract
Borepin, a 7‐membered boron‐containing heterocycle, has become an emerging molecular platform for the development of new materials and optoelectronics. While electron‐deficient borepins are well‐established, reduced electron‐rich species have remained elusive. Herein we report the first isolable, crystalline borepin radical (2 a, 2 b) and anion (3 a, 3 b) complexes, which have been synthesized by potassium graphite (KC8) reduction of cyclic(alkyl)(amino) carbene‐dibenzo[b,d]borepin precursors. Borepin radicals and anions have been characterized by EPR or NMR, elemental analysis, X‐ray crystallography, and cyclic voltammetry. In addition, the bonding features have been investigated computationally using density functional theory.
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Affiliation(s)
- Kimberly K Hollister
- Department of Chemistry, University of Virginia, 409 McCormick Rd./PO Box 400319, Charlottesville, VA 22904, USA
| | - Wenlong Yang
- Department of Chemistry, University of Virginia, 409 McCormick Rd./PO Box 400319, Charlottesville, VA 22904, USA
| | - Ranajit Mondol
- Department of Chemistry, University of Virginia, 409 McCormick Rd./PO Box 400319, Charlottesville, VA 22904, USA
| | - Kelsie E Wentz
- Department of Chemistry, University of Virginia, 409 McCormick Rd./PO Box 400319, Charlottesville, VA 22904, USA
| | - Andrew Molino
- Department of Chemistry and Physics, La Trobe Institute for Molecular Science, Latrobe University, Melbourne, 3086, Victoria, Australia
| | - Aishvaryadeep Kaur
- Department of Chemistry and Physics, La Trobe Institute for Molecular Science, Latrobe University, Melbourne, 3086, Victoria, Australia
| | - Diane A Dickie
- Department of Chemistry, University of Virginia, 409 McCormick Rd./PO Box 400319, Charlottesville, VA 22904, USA
| | - Gernot Frenking
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35043, Marburg, Germany
| | - Sudip Pan
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35043, Marburg, Germany
| | - David J D Wilson
- Department of Chemistry and Physics, La Trobe Institute for Molecular Science, Latrobe University, Melbourne, 3086, Victoria, Australia
| | - Robert J Gilliard
- Department of Chemistry, University of Virginia, 409 McCormick Rd./PO Box 400319, Charlottesville, VA 22904, USA
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4
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Hollister KK, Yang W, Mondol R, Wentz KE, Molino A, Kaur A, Dickie DA, Frenking G, Pan S, Wilson DJD, Gilliard RJ. Isolation of Stable Borepin Radicals and Anions. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202202516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Kimberly K. Hollister
- Department of Chemistry University of Virginia 409 McCormick Rd./PO Box 400319 Charlottesville VA 22904 USA
| | - Wenlong Yang
- Department of Chemistry University of Virginia 409 McCormick Rd./PO Box 400319 Charlottesville VA 22904 USA
| | - Ranajit Mondol
- Department of Chemistry University of Virginia 409 McCormick Rd./PO Box 400319 Charlottesville VA 22904 USA
| | - Kelsie E. Wentz
- Department of Chemistry University of Virginia 409 McCormick Rd./PO Box 400319 Charlottesville VA 22904 USA
| | - Andrew Molino
- Department of Chemistry and Physics La Trobe Institute for Molecular Science Latrobe University Melbourne 3086, Victoria Australia
| | - Aishvaryadeep Kaur
- Department of Chemistry and Physics La Trobe Institute for Molecular Science Latrobe University Melbourne 3086, Victoria Australia
| | - Diane A. Dickie
- Department of Chemistry University of Virginia 409 McCormick Rd./PO Box 400319 Charlottesville VA 22904 USA
| | - Gernot Frenking
- Fachbereich Chemie Philipps-Universität Marburg Hans-Meerwein-Strasse 4 35043 Marburg Germany
| | - Sudip Pan
- Fachbereich Chemie Philipps-Universität Marburg Hans-Meerwein-Strasse 4 35043 Marburg Germany
| | - David J. D. Wilson
- Department of Chemistry and Physics La Trobe Institute for Molecular Science Latrobe University Melbourne 3086, Victoria Australia
| | - Robert J. Gilliard
- Department of Chemistry University of Virginia 409 McCormick Rd./PO Box 400319 Charlottesville VA 22904 USA
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5
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Pearce KG, Canham EPF, Nixon JF, Crossley IR. A Benzodiphosphaborolediide. Chemistry 2021; 27:16342-16346. [PMID: 34586681 DOI: 10.1002/chem.202103427] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Indexed: 01/06/2023]
Abstract
The first example of a diphosphaborolediide, the benzo-fused [C6 H4 P2 BPh]2- (12- ), is prepared from ortho-bis(phosphino)benzene (C6 H4 {PH2 }) and dichlorophenylborane, via a sequential lithiation approach. The dilithio-salt can be obtained as an oligomeric THF solvate or discrete TMEDA adduct, both of which are fully characterized, including by X-ray diffraction. Alongside NICS calculations, data strongly suggest some aromaticity within 12- , which is further supported by preliminary coordination studies that demonstrate η5 -coordination to a zerovalent molybdenum center, as observed crystallographically for the oligomeric [{Mo(CO)3 (η5 -1)}{μ-η1 -Mo(CO)3 (TMEDA)}2 ] ⋅ [μ-Li(THF)][μ-Li(TMEDA)].
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Affiliation(s)
- Kyle G Pearce
- Department of Chemistry, University of Sussex, Falmer, Brighton, BN1 9QJ, UK
| | - Elinor P F Canham
- Department of Chemistry, University of Sussex, Falmer, Brighton, BN1 9QJ, UK
| | - John F Nixon
- Department of Chemistry, University of Sussex, Falmer, Brighton, BN1 9QJ, UK
| | - Ian R Crossley
- Department of Chemistry, University of Sussex, Falmer, Brighton, BN1 9QJ, UK
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Abstract
Structurally authenticated free B-alkyl boroles are presented and electronic implications of alkyl substitution were assessed. Deprotonation of a boron-bound exocyclic methyl group in a B-methyl borole yields the first 5-boratafulvene anion-an isomer to boratabenzene. Boratafulvene was structurally characterized and its electronic structure probed by DFT calculations. The pKa value of the exocyclic B-CH3 in a set of boroles was computationally approximated and confirmed a pronounced acidic character caused by the boron atom embedded in an anti-aromatic moiety. The non-aromatic boratafulvene reacts as a C-centered nucleophile with the mild electrophile Me3 SnCl to give a stannylmethyl borole, regenerating the anti-aromaticity. As nucleophilic synthons for boroles, boratafulvenes thus open an entirely new avenue for synthetic strategies toward this highly reactive class of heterocycles. Boratafulvene reacts as a methylene transfer reagent in a bora-Wittig-type reaction generating a borole oxide.
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Affiliation(s)
- Tobias Heitkemper
- Institut für Anorganische ChemieGeorg-August-Universität GöttingenTammannstrasse 437077GöttingenGermany
| | - Leonard Naß
- Institut für Anorganische ChemieGeorg-August-Universität GöttingenTammannstrasse 437077GöttingenGermany
| | - Christian P. Sindlinger
- Institut für Anorganische ChemieGeorg-August-Universität GöttingenTammannstrasse 437077GöttingenGermany
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7
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Heitkemper T, Naß L, Sindlinger CP. Ein Boratafulven. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202107968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Tobias Heitkemper
- Institut für Anorganische Chemie Georg-August-Universität Göttingen Tammannstraße 4 37077 Göttingen Deutschland
| | - Leonard Naß
- Institut für Anorganische Chemie Georg-August-Universität Göttingen Tammannstraße 4 37077 Göttingen Deutschland
| | - Christian P. Sindlinger
- Institut für Anorganische Chemie Georg-August-Universität Göttingen Tammannstraße 4 37077 Göttingen Deutschland
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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: 16] [Impact Index Per Article: 5.3] [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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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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