A Planar Nickelaspiropentane Complex with Magnesium-Based Metalloligands: Synthesis, Structure, and Synergistic Dihydrogen Activation - Archive ouverte HAL
Article Dans Une Revue Journal of the American Chemical Society Année : 2022

A Planar Nickelaspiropentane Complex with Magnesium-Based Metalloligands: Synthesis, Structure, and Synergistic Dihydrogen Activation

Résumé

The nature of transition-metal–olefin bonding has been explained by the Dewar–Chatt–Duncanson model within a continuum of two extremes, namely, a π-complex and a metallacyclopropane. The textbook rule suggests that a low-spin late-transition-metal–ethylene complex more likely forms a π-complex rather than a metallacyclopropane. Herein, we report a low-spin late-transition-metal–bis-ethylene complex forming an unprecedented planar metalla-bis-cyclopropane structure with magnesium-based metalloligands. Treatment of LMgEt (L = [(DippNCMe)2CH]−, Dipp = 2,6-iPr2C6H3) with Ni(cod)2 (cod = 1,5-cyclooctadiene) formed the heterotrimetallic complex (LMg)2Ni(C2H4)2, which features a linear Mg–Ni–Mg linkage and a planar coordination geometry at the nickel center. Both structural features and computational studies strongly supported the Ni(C2H4)2 moiety as a nickelaspiropentane. The exposure of (LMg)2Ni(C2H4)2 to 1 bar H2 at room temperature produced a four-hydride-bridged complex (LMg)2Ni(μ-H)4. The profile of H2 activation was elucidated by density functional theory calculations, which indicated a novel Mg/Ni cooperative activation mechanism with no oxidation occurring at the metal center, differing from the prevailing mono-metal-based redox mechanism. Moreover, the heterotrimetallic complex (LMg)2Ni(C2H4)2 catalyzed the hydrogenation of a wide range of unsaturated substrates under mild conditions.

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Dates et versions

hal-04037097 , version 1 (20-03-2023)

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Yanping Cai, Shengjie Jiang, Thayalan Rajeshkumar, Laurent Maron, Xin Xu. A Planar Nickelaspiropentane Complex with Magnesium-Based Metalloligands: Synthesis, Structure, and Synergistic Dihydrogen Activation. Journal of the American Chemical Society, 2022, 144 (36), pp.16647-16655. ⟨10.1021/jacs.2c07402⟩. ⟨hal-04037097⟩
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