Synthesis,Coordination Behavior,and Reduction Chemistry of Cymantrenyl‐1,3‐bis(2,3,4,5‐tetraphenyl)borole |
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Authors: | Prof. Dr. Holger Braunschweig Alexander Damme Dr. Daniela Gamon Hauke Kelch Dr. Ivo Krummenacher Dr. Thomas Kupfer Dr. Krzysztof Radacki |
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Affiliation: | Institut für Anorganische Chemie, Julius–Maximilians Universit?t Würzburg, Am Hubland, 97074 Würzburg (Germany), Fax: (+49)?931‐31‐84623 |
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Abstract: | We describe the synthesis of base‐free bisborole [Cym?(BC4Ph4)2]—Cym?=(OC)3Mn(η5‐C5H3)—and its transformation into two fully characterized Lewis acid–base adducts with pyridine bases of the type 4‐R? NC5H4 (R=tBu, NMe2). The results of electrochemical, as well as NMR and UV/Vis spectroscopic studies on [Cym?(BC4Ph4)2] and the related monoborole derivative [Cym(BC4Ph4)]—Cym=(OC)3Mn(η5‐C5H4)—provided conclusive evidence for 1) the enhanced Lewis acidity of the two boron centers that result from conjugation of two borole fragments, and 2) the fact that Mn? B bonding interactions between the Lewis acidic borole moieties and the Mn center are considerably less pronounced for bisborole [Cym?(BC4Ph4)2]. In addition, the reduction chemistry of [Cym?(BC4Ph4)2] has been studied in detail, both electrochemically and chemically. Accordingly, chemical reduction of [Cym?(BC4Ph4)2] with magnesium anthracene afforded the corresponding tetraanion, which features a rare Mg? OC bonding mode in the solid state. |
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Keywords: | aromaticity boroles cymantrene electrochemistry reduction |
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