om048992v_si_001.pdf (276.75 kB)
Investigations into the Stability of Tethered Palladium(II) Pincer Complexes during Heck Catalysis
journal contribution
posted on 2005-08-29, 00:00 authored by William J. Sommer, Kunquan Yu, John S. Sears, Yaying Ji, Xiaolai Zheng, Robert J. Davis, C. David Sherrill, Christopher W. Jones, Marcus WeckA variety of palladated PCP pincer complexes are covalently tethered onto polymeric and
silica supports via either amide or ether linkages and are evaluated in the Heck reaction of
iodobenzene and n-butyl acrylate. The decomposition under reaction conditions of all
complexes studied is established through poisoning and kinetic studies. Furthermore, the
initial steps of the decomposition pathway of PCP as well as SCS pincer Pd(II) complexes
are proposed and validated using in situ NMR, mass spectroscopy, and XAS as well as
computational methods. These findings together with our previous reports strongly suggest
that all Pd(II) pincer complexes are simply precatalysts during the Heck reaction that
decompose to form catalytically active Pd(0) species.