Investigations into the Stability of Tethered Palladium(II) Pincer Complexes during Heck Catalysis

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• 作者：William J. Sommer ; Kunquan Yu ; John S. Sears ; Yaying Ji ; Xiaolai Zheng ; Robert J. Davis ; C. David Sherrill ; Christopher W. Jones ; and Marcus Weck
• 刊名：Organometallics
• 出版年：2005
• 出版时间：August 29, 2005
• 年：2005
• 卷：24
• 期：18
• 页码：4351 - 4361
• 全文大小：254K
• 年卷期：v.24,no.18(August 29, 2005)
• ISSN：1520-6041

文摘

A variety of palladated PCP pincer complexes are covalently tethered onto polymeric andsilica supports via either amide or ether linkages and are evaluated in the Heck reaction ofiodobenzene and n-butyl acrylate. The decomposition under reaction conditions of allcomplexes studied is established through poisoning and kinetic studies. Furthermore, theinitial steps of the decomposition pathway of PCP as well as SCS pincer Pd(II) complexesare proposed and validated using in situ NMR, mass spectroscopy, and XAS as well ascomputational methods. These findings together with our previous reports strongly suggestthat all Pd(II) pincer complexes are simply precatalysts during the Heck reaction thatdecompose to form catalytically active Pd(0) species.