Synthesis of Palladium Benzyl Complexes from the Reaction of PdCl₂[P(OPh)₃]₂ with Benzyl Bromide and Triethylamine: Important Intermediates in Catalytic Carbonylation

The palladium complex PdCl2(P(OPh)3)2 is reduced to Pd(P(OPh)3)4 by tertiary amines (NEt3, NPr3, NBu3) in the presence of water. The formation of aldehydes and corresponding secondary amines in this reaction has confirmed the role of amines as reducing agents. The new palladium benzyl complexes, cis-[PdBr2(CH2Ph)(P(OPh)3)][PhCH2NEt3] (1) and [PdBr(CH2Ph)(P(O-o-MeC6H4)3)]2 (2a), were obtained in one-step syntheses from PdCl2(P(OPh)3)2 or PdCl2[P(O-o-MeC6H4)3)]2, NEt3, and benzyl bromide and X-ray characterized. The air oxidation of complex 1 led to [PdBr3(P(OPh)3)][PhCH2NEt3] (4) with the abstraction of benzaldehyde.