Influence of the Pd(II) Coordination Model on the Catalytic Performance of Pd鈥揚Ph2鈥揝BA-15 in C鈥揅 Bond Forming Reactions

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• 作者：Jianlin Huang ; Meitao Wang ; Siyong Zhang ; Bingwen Hu ; Hexing Li
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：November 17, 2011
• 年：2011
• 卷：115
• 期：45
• 页码：22514-22522
• 全文大小：1077K
• 年卷期：v.115,no.45(November 17, 2011)
• ISSN：1932-7455

文摘

A series of Pd鈥揚Ph₂鈥揝BA-15 catalysts were synthesized by coordinating Pd(II) ions with PPh₂ ligands originally bonded to SBA-15 support. The ³¹P CP MAS NMR spectra demonstrated that there were two kinds of coordination models coexisting in the Pd鈥揚Ph₂鈥揝BA-15 catalysts. At high P-content, the Pd nucleus preferentially coordinated with two PPh₂ ligands (referred as Pd-2P model) owing to the strong chelating bond. However, at low P-content, the Pd nucleus mainly coordinated with one PPh₂ ligand (denoted as Pd-1P model) due to long distance between the neighboring PPh₂ ligands. The Pd鈥揚Ph₂鈥揝BA-15-con prepared by co-condensation between PdCl₂[PPh₂(CH₂)₂Si(OCH₂CH₃)₃]₂ and TEOS contained the pure Pd-2P model. The Pd-2P coordination model exhibited higher activity and better selectivity than the Pd-1P model in various C鈥揅 bond forming reactions including Suzuki, Heck, Barbier, and Sonogashira reactions, which was discussed by considering the electronic state and the coordination configuration of Pd(II) active sites, together with their stability against leaching.