Lewis Superacidic Tellurenyl Cation-Induced Electrophilic Activation of an Inert Carborane
| Autor: | Zdeněk Černošek, Sergey V. Makarov, Antonín Lyčka, Martin Hejda, Daniel Duvinage, Enno Lork, Jens Beckmann, Stefan Mebs, Sergey Yu. Ketkov, Libor Dostál, Jan Macháček |
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| Rok vydání: | 2021 |
| Předmět: |
bond activation
carboranes Proton Communication Organic Chemistry Lewis superacids chemistry.chemical_element General Chemistry Medicinal chemistry Catalysis Communications Ion chemistry tellurium Electrophile Carborane Moiety Tellurium Brønsted–Lowry acid–base theory Boron boron 500 Naturwissenschaften und Mathematik::540 Chemie::540 Chemie und zugeordnete Wissenschaften |
| Zdroj: | Chemistry (Weinheim an Der Bergstrasse, Germany) |
| DOI: | 10.17169/refubium-32840 |
| Popis: | The aryltellurenyl cation [2‐(tBuNCH)C6H4Te]+, a Lewis super acid, and the weakly coordinating carborane anion [CB11H12]−, an extremely weak Brønsted acid (pK a=131.0 in MeCN), form an isolable ion pair complex [2‐(tBuNCH)C6H4Te][CB11H12], in which the Brønsted acidity (pK a 7.4 in MeCN) of the formally hydridic B−H bonds is dramatically increased by more than 120 orders of magnitude. The electrophilic activation of B−H bonds in the carborane moiety gives rise to a proton transfer from boron to nitrogen at slightly elevated temperatures, as rationalized by the isolation of a mixture of the zwitterionic isomers 12‐ and 7‐[2‐(tBuN{H}CH)C6H4Te(CB11H11)] in ratios ranging from 62 : 38 to 80 : 20. B−H bond activation: The Lewis superacidic aryltellurenyl cation [2‐(tBuNCH)C6H4Te]+ increases the Brønsted acidity of the weakly coordinating carborane anion (CB11H12)− by more than 120 orders of magnitude. Upon heating, the formal B−H bond is converted into an acidic N−H bond, while a Te−B bond is formed. A mechanism for the electrophilic substitution is proposed. |
| Databáze: | OpenAIRE |
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