Tritopic NHC Precursors: Unusual Nickel Reactivity and Ethylene Insertion into a C(sp3)–H Bond |
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Authors: | Xiaoyu Ren Dr Christophe Gourlaouen Dr Marcel Wesolek Dr Pierre Braunstein |
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Institution: | 1. Laboratoire de Chimie de Coordination, Institut de Chimie (UMR 7177 CNRS), Université de Strasbourg, 4 rue Blaise Pascal, 67081 Strasbourg Cedex, France;2. Laboratoire de Chimie Quantique, Institut de Chimie (UMR 7177 CNRS), Université de Strasbourg, 4 rue Blaise Pascal, 67081 Strasbourg Cedex, France |
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Abstract: | The imidazolium chloride C3H3N(C3H6NMe2)N{C(Me)(=NDipp)}]Cl ( 1 ; Dipp=2,6‐diisopropyl phenyl), a potential precursor to a tritopic NimineCNHCNamine pincer‐type ligand, reacted with Ni(cod)2] to give the NiI‐NiI complex 2 , which contains a rare cod‐derived η3‐allyl‐type bridging ligand. The implied intermediate formation of a nickel hydride through oxidative addition of the imidazolium C−H bond did not occur with the symmetrical imidazolium chloride C3H3N2{C(Me)(=NDipp)}2]Cl ( 3 ). Instead, a Ni−C(sp3) bond was formed, leading to the neutral NimineCHNimine pincer‐type complex NiC3H3N2{C(Me)(=NDipp)}2]Cl ( 4 ). Theoretical studies showed that this highly unusual feature in nickel NHC chemistry is due to steric constraints induced by the N substituents, which prevent Ni−H bond formation. Remarkably, ethylene inserted into the C(sp3)−H bond of 4 without nickel hydride formation, thus suggesting new pathways for the alkylation of non‐activated C−H bonds. |
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Keywords: | Alkylierungen N-heterocyclische Carbene Nickel Oxidative Addition Pinzettenliganden |
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