Direct metal–carbon bonding in symmetric bis(C–H) agostic nickel(i) complexes |
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Authors: | Weiying He D. Dawson Beattie Hao Zhou Eric G. Bowes Laurel L. Schafer Jennifer A. Love Pierre Kennepohl |
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Affiliation: | Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary Alberta T2N 1N4 Canada.; Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver BC V6T 1Z1 Canada |
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Abstract: | Agostic interactions are examples of σ-type interactions, typically resulting from interactions between C–H σ-bonds with empty transition metal d orbitals. Such interactions often reflect the first step in transition metal-catalysed C–H activation processes and thus are of critical importance in understanding and controlling σ bond activation chemistries. Herein, we report on the unusual electronic structure of linear electron-rich d9 Ni(i) complexes with symmetric bis(C–H) agostic interactions. A combination of Ni K edge and L edge XAS with supporting TD-DFT/DFT calculations reveals an unconventional covalent agostic interaction with limited contributions from the valence Ni 3d orbitals. The agostic interaction is driven via the empty Ni 4p orbitals. The surprisingly strong Ni 4p-derived agostic interaction is dominated by σ contributions with minor π contributions. The resulting ligand–metal donation occurs directly along the C–Ni bond axis, reflecting a novel mode of bis-agostic bonding.Symmetric Ni(i) agostic complexes reveal an unusual mode of bonding that is dominated by direct carbon-to-metal charge transfer. |
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