α-Substituted Benzylic Complexes of Palladium(II) as Precursors of Palladium Hydrides

Abstract

The adoption of a pseudoallylic (η3) form makes palladium benzylic derivatives a class of stabilized palladium alkyls that can undergo β-H elimination reactions in a more controlled way. α- (Pentafluorophenylmethyl)benzyl palladium complexes have been studied and they decompose by β-H elimination to give palladium hydrides that, depending on the auxil- iary ligands can: a) transmetalate to another palladium atom and, by reductive elimina- tion, give hydrogenated products; this process is favored for a combination of bridging ligands (i.e halogens) and low coordinating ligands. b) Be used as a hydride source and get trapped by a diene to give palladium allylic derivatives. The presence of carbon mon- oxide does not induce a β-H elimination reactions and only CO insertion into the Pd- benzyl bond to give acyl derivatives is observed.