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A Journey from Benzoborirene to Benzoborole-Supported 1,2-Diimine and Antiaromatic Borolediide |
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| Authors: | Dr. Xiaocui Liu Myron Heinz Dr. Junyi Wang Leibo Tan Prof. Max C. Holthausen Prof. Qing Ye |
| Affiliation: | 1. State Key Laboratory of Traditional Chinese Medicine Syndromes, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, 510000 Guangzhou, P. R. China Department of Chemistry, Southern University of Science and Technology, 518055 Shenzhen, P. R. China These authors contributed equally to this work.;2. Institute of Inorganic and Analytical Chemistry, Goethe-Universität, 60438 Frankfurt am Main, Germany These authors contributed equally to this work.;3. Department of Chemistry, Southern University of Science and Technology, 518055 Shenzhen, P. R. China;4. Institute für Anorganische Chemie and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, 97074 Würzburg, Germany;5. Institute of Inorganic and Analytical Chemistry, Goethe-Universität, 60438 Frankfurt am Main, Germany |
| Abstract: | The reaction of benzoborirene with one equivalent of isocyanides leads to benzene-fused boretes bearing one imine function, while the reaction with two equivalents of isocyanide affords 2,3-dihydro-2,3-diiminoboroles with perfect regioselectivity. The isocyanide double insertion products represent a novel type of 1,2-diimine with a benzoborole backbone. The reduction chemistry of the benzoborole-supported 1,2-diimine was investigated. Single- and two-electron reduction allow for the isolation and full characterization of a radical anion and a dianion, respectively. In stark contrast to the ordinary boroles, which should turn aromatic by accepting two electrons, the antiaromatic character of the benzoborole backbone is highlighted upon reduction, thus presenting a rare example of antiaromatic borole dianion. Detailed quantum chemical calculations provide a rationale for the observed regioselectivity and the electronic structure of the reduced borole diimine species. |
| Keywords: | Antiaromaticity Borirene Borole Diimine Radical |