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Lu W, Hensiek N, Saha K, Dewhurst RD, Härterich M, Pranckevicius C, Hagspiel S, Dietz M, Krummenacher I, Braunschweig H. Electron-Precise Dicationic Tetraboranes: Syntheses, Structures and Rearrangement to an Alkylidene Borate-Borenium Zwitterion and a 1,3-Azaborinine. Chemistry 2023; 29:e202300644. [PMID: 37272320 DOI: 10.1002/chem.202300644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 06/02/2023] [Accepted: 06/02/2023] [Indexed: 06/06/2023]
Abstract
Carbene-stabilized symmetrical and unsymmetrical dicationic tetraboranes, featuring an electron-precise tetraborane chain, were synthesized and fully characterized. Reactions of these tetraboranes with reductants/bases give rise to different outcomes according to the conditions employed, including: 1) reduction and rearrangement of the tetraborane chain to give a zwitterionic alkylidene borate-borenium species; 2) cleavage of the tetraborane chain to afford a 1,3-azaborinine; and 3) reduction of the supporting ligands to provide a diamino dipotassium salt. The zwitterionic alkylidene borate-borenium species can be viewed as an analogue of the base-stabilized diborenes. NMR spectroscopy and DFT calculations reveal a highly polarized B-B bond in the zwitterionic alkylidene borate-borenium, in which the formal oxidation states of the boron atoms can be considered as -1 and +2. These results suggest the considerable potential of tetraboranes as synthons for low-valent boron species.
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Affiliation(s)
- Wei Lu
- 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
- Key Laboratory of Green Chemistry & Technology of Ministry of Education, College of Chemistry, Sichuan University, 29 Wangjiang Road, Chengdu, 610064, P. R. China
| | - Nicola Hensiek
- 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
| | - Koushik Saha
- 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
| | - Rian D Dewhurst
- 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
| | - Marcel Härterich
- 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
| | - Conor Pranckevicius
- 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
| | - Stephan Hagspiel
- 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
| | - 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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Kistner L, Kowatsch D, Marz A, Kaifer E, Himmel H. Directed Synthesis and Chemistry of Unsymmetric Dicationic Diboranes and Their Use in Frustrated Lewis Pair-like Chemistry. Chemistry 2022; 28:e202104016. [PMID: 35061309 PMCID: PMC9305129 DOI: 10.1002/chem.202104016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Indexed: 11/15/2022]
Abstract
The chemistry of dicationic diboranes with two BII atoms that are engaged in direct B-B bonding is by enlarge unexplored, although these molecules have intriguing properties due to their combined Lewis acidic and electron-donor properties. Unsymmetric dicationic diboranes are extremely rare, but especially attractive due to their polarized B-B bond. In this work we report the directed synthesis of several stable unsymmetric dicationic diboranes by reaction between the electron-rich ditriflato-diborane B2 (hpp)2 (OTf)2 (hpp=1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-α]pyrimidinate) and phosphino-pyridines, establishing B-N and B-P bonds with the diborane concomitant with triflate elimination. In the case of 2-((ditertbutylphosphino)methyl)pyridine, the B-N bond is formed instantly, but the B-P bond formation requires (due to steric constraints) several days at ambient conditions for completion, creating an intermediate that could be used for frustrated Lewis pair (FLP)-like chemistry. Here we test its reaction with an aldehyde, and propose a new type of FLP-like chemistry.
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Affiliation(s)
- Lucas Kistner
- Anorganisch-Chemisches InstitutRuprecht-Karls Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Dario Kowatsch
- Anorganisch-Chemisches InstitutRuprecht-Karls Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Andreas Marz
- Anorganisch-Chemisches InstitutRuprecht-Karls Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Elisabeth Kaifer
- Anorganisch-Chemisches InstitutRuprecht-Karls Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Hans‐Jörg Himmel
- Anorganisch-Chemisches InstitutRuprecht-Karls Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
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Krantz KE, Weisflog SL, Frey NC, Yang W, Dickie DA, Webster CE, Gilliard RJ. Planar, Stair‐Stepped, and Twisted: Modulating Structure and Photophysics in Pyrene‐ and Benzene‐Fused N‐Heterocyclic Boranes. Chemistry 2020; 26:10072-10082. [DOI: 10.1002/chem.202002118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Indexed: 01/23/2023]
Affiliation(s)
- Kelsie E. Krantz
- Department of Chemistry University of Virginia 409 McCormick Rd./ PO Box 400319 Charlottesville VA 22904 USA
| | - Sarah L. Weisflog
- Department of Chemistry University of Virginia 409 McCormick Rd./ PO Box 400319 Charlottesville VA 22904 USA
| | - Nathan C. Frey
- Department of Chemistry Mississippi State University, Box 9573 Mississippi State MS 39762 USA
| | - Wenlong Yang
- Department of Chemistry University of Virginia 409 McCormick Rd./ PO Box 400319 Charlottesville VA 22904 USA
| | - Diane A. Dickie
- Department of Chemistry University of Virginia 409 McCormick Rd./ PO Box 400319 Charlottesville VA 22904 USA
| | - Charles Edwin Webster
- Department of Chemistry Mississippi State University, Box 9573 Mississippi State MS 39762 USA
| | - Robert J. Gilliard
- Department of Chemistry University of Virginia 409 McCormick Rd./ PO Box 400319 Charlottesville VA 22904 USA
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