A Mixed Phosphine−Iminophosphorane Tetradentate Ligand: Synthesis, Coordination to Group 10 Metal Centers, and Use as Catalyst in Suzuki−Miyaura Coupling

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• 作者：Antoine Buchard ; Bruno Komly ; Audrey Auffrant ; Xavier F. Le Goff ; Pascal Le Floch
• 刊名：Organometallics
• 出版年：2008
• 出版时间：September 8, 2008
• 年：2008
• 卷：27
• 期：17
• 页码：4380-4385
• 全文大小：216K
• 年卷期：v.27,no.17(September 8, 2008)
• ISSN：1520-6041

文摘

The novel tetradentate ligand 1, associating two phosphines and two iminophosphorane moieties, was easily synthesized from commercially available bis(diphenylphosphino)methane and ethylenediamine via the preparation of the bis(phosphine−aminophosphonium) adduct 1-(HBr)₂. Deprotonation of this salt afforded the corresponding tetradentate P₂N₂ phosphine−iminophosphorane ligand 1. Coordination to Ni(II) and Pd(II) metal centers afforded complexes 2 and 3, respectively, characterized by multinuclear NMR and X-ray analysis. Both cationic complexes adopt a square-planar geometry around the metal, all phosphorus and nitrogen atoms being coordinated. In contrast to most iminophosphorane complexes, 2 and 3 could be handled in water without any apparent decomposition. Their catalytic activity was evaluated in Suzuki−Miyaura coupling. These reactions were conducted in toluene, water, or a biphasic toluene/water medium in the presence of a phase-transfer agent. Under these last conditions, the Pd catalyst 3 (0.1 mol % catalyst loading) could be reused for five cycles without noticeable loss of activity.