Cobalt Nanoparticles Formed upon Reaction of Cp*Co(III) Metallacycles with Na[BHEt3] Show Catalytic Activity in the Hydrosilylation of Aryl Ketones,Aldehydes and Nitriles |
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Authors: | Carmen Antuña-Hörlein Dr. Fule Wu Dr. Christophe Deraedt Corinne Bouillet Dr. Jean-Pierre Djukic |
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Affiliation: | 1. Laboratoire de Chimie et Systémique Organométallique, Institut de Chimie de Strasbourg (UMR 7177) CNRS/Université de Strasbourg, 4 rue Blaise Pascal, 67000 Strasbourg Cedex, France;2. Institut de Physique et Chimie des Matériaux de Strasbourg (UMR 7504), CNRS/ Université de Strasbourg, 23 rue du Loess, 67200 Strasbourg, France |
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Abstract: | The reactivity of the 2-phenylpyridine-derived [Cp*CoI(phpy-κC,N)] metallacycle towards Et3SiH and hydrides was evaluated. The treatment of the same Co(III) complex with Na[BHEt3] resulted in its decomposition into cobalt nanoparticles. The hydride-promoted decomposition of the metallacycle involves the transient formation of an elusive hydrido-cobalt(III) intermediate, the traces of which were detected by 1H NMR spectroscopy at sub-ambient temperature. The Co nanoparticles produced from a 5 mol% and 10 mol% load of cobaltacycle and Na[BHEt3] respectively contain Co(0) that is responsible for the hydrosilylation by Et3SiH of arylketones into silylalkyl ethers. To minimize the residual side reduction of carbonyls by Na[BHEt3], a mixture of 5 mol% of the latter with 5 mol% of BEt3 was found to produce optimal hydrosilylation yields at 40 °C in 2 h. Under similar conditions, several arylnitriles were mono-hydrosilylated into N-silyl-imines in yields ranging from 68 to 100 %. |
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Keywords: | Cobalt Hydrosilylation Homogeneous catalysis Metallacycle Nanoparticles |
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