In situ formation of palladium(0) from a P,C-palladacycle

In DMF at 80 degrees C, a Pd-0 complex is generated in situ from the dimeric P,C-palladacycle (1) in the absence of any reducing agents, presumably via a reductive elimination. The Pd-0 complex formed in an endergonic equilibrium has been trapped and stabilized by an additional P(o-Tol)(3) and has been detected in cyclic voltammetry by its oxidation peak. Its formation is favored by acetate anions (often used as base in Heck reactions) via the formation of a monomeric anionic P,C-palladacycle ligated by acetate ions. As postulated, P,C-palladacycles are a reservoir of monophosphine-Pd-0 complexes active in oxidative additions with aryl halides. (c) 2005 Elsevier Ltd. All rights reserved.