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Oligo(borolyl)benzenes—Synthesis and Properties

Authors

  • Prof. Dr. Holger Braunschweig,

    Corresponding author
    1. Institut für Anorganische Chemie, Julius-Maximilians Universität Würzburg, Am Hubland, 97074 Würzburg (Germany), Fax: (+49) 931-31-84623
    • Institut für Anorganische Chemie, Julius-Maximilians Universität Würzburg, Am Hubland, 97074 Würzburg (Germany), Fax: (+49) 931-31-84623===

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  • Prof. Ching-Wen Chiu,

    1. Department of Chemistry, National Taiwan University, Roosevelt Rd. 1, 10617 Taipei (Taiwan)
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  • Alexander Damme,

    1. Institut für Anorganische Chemie, Julius-Maximilians Universität Würzburg, Am Hubland, 97074 Würzburg (Germany), Fax: (+49) 931-31-84623
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  • Prof. Dr. Bernd Engels,

    1. Institut für Physikalische und Theoretische Chemie, Bayerische Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg (Germany)
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  • Dr. Daniela Gamon,

    1. Institut für Anorganische Chemie, Julius-Maximilians Universität Würzburg, Am Hubland, 97074 Würzburg (Germany), Fax: (+49) 931-31-84623
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  • Christian Hörl,

    1. Institut für Anorganische Chemie, Julius-Maximilians Universität Würzburg, Am Hubland, 97074 Würzburg (Germany), Fax: (+49) 931-31-84623
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  • Dr. Thomas Kupfer,

    1. Institut für Anorganische Chemie, Julius-Maximilians Universität Würzburg, Am Hubland, 97074 Würzburg (Germany), Fax: (+49) 931-31-84623
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  • Dr. Ivo Krummenacher,

    1. Institut für Anorganische Chemie, Julius-Maximilians Universität Würzburg, Am Hubland, 97074 Würzburg (Germany), Fax: (+49) 931-31-84623
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  • Dr. Krzysztof Radacki,

    1. Institut für Anorganische Chemie, Julius-Maximilians Universität Würzburg, Am Hubland, 97074 Würzburg (Germany), Fax: (+49) 931-31-84623
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  • Christof Walter

    1. Institut für Physikalische und Theoretische Chemie, Bayerische Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg (Germany)
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Abstract

Herein, we report the synthesis of boroles that are linked by a conjugated phenylene spacer. The characterization of these compounds was completed by NMR and UV/Vis spectroscopy, as well as X-ray crystal diffraction. Furthermore, the coordination behavior of these oligoboroles towards five electronically and sterically disparate pyridine derivatives was studied and revealed fundamental differences in the properties of the resulting adducts. The experimental results were supported by density functional theory (DFT) calculations that showed a charge-transfer effect upon formation of the pyridine-4-carbonitrile adduct. By chemical reduction of a tris(borolyl)-substituted benzene derivative, a hexaanion was isolated as a result of a two-electron reduction of each borolyl moiety. The interaction of the borolyl units through the aryl spacer, and the possible increase of the Lewis acidity due to the conjugation of the borolyl moieties, were investigated by base transfer reactions.

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