Toward Transition-Metal-Templated Construction of Arylated B4 Chains by Dihydroborane Dehydrocoupling |
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Authors: | Dr. Carsten Lenczyk Dr. Dipak Kumar Roy Kai Oberdorf Dr. Jörn Nitsch Dr. Rian D. Dewhurst Dr. Krzysztof Radacki Prof. Dr. Jean-François Halet Prof. Dr. Todd B. Marder Prof. Dr. Matthias Bickelhaupt Prof. Dr. Holger Braunschweig |
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Affiliation: | 1. Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg (Germany), and Institute for, Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany;2. Univ Rennes CNRS, Institut des Sciences Chimiques de Rennes, UMR 6226, 35000 Rennes, France;3. Department of Theoretical Chemistry and Amsterdam Center for, Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam (The Netherlands), and Institute for Molecules and Materials (IMM), Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands |
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Abstract: | The reactivity of a diruthenium tetrahydride complex towards three selected dihydroboranes was investigated. The use of [DurBH2] (Dur=2,3,5,6-Me4C6H) and [(Me3Si)2NBH2] led to the formation of bridging borylene complexes of the form [(Cp*RuH)2BR] (Cp*=C5Me5; 1 a : R=Dur; 1 b : R=N(SiMe3)2) through oxidative addition of the B−H bonds with concomitant hydrogen liberation. Employing the more electron-deficient dihydroborane [3,5-(CF3)2-C6H3BH2] led to the formation of an anionic complex bearing a tetraarylated chain of four boron atoms, namely Li(THF)4[(Cp*Ru)2B4H5(3,5-(CF3)2C6H3)4] ( 4 ), through an unusual, incomplete threefold dehydrocoupling process. A comparative theoretical investigation of the bonding in a simplified model of 4 and the analogous complex nido-[1,2(Cp*Ru)2(μ-H)B4H9] ( I ) indicates that there appear to be no classical σ-bonds between the boron atoms in complex I , whereas in the case of 4 the B4 chain better resembles a network of three B−B σ bonds, the central bond being significantly weaker than the other two. |
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Keywords: | B−H activation boron dehydrocoupling ruthenium transition metal |
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