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 PdCl 2 (P(OPh) 3 ) 2 is reduced to Pd(P(OPh) 3 ) 4 by tertiary amines (NEt 3, NPr 3, NBu 3 ) 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 -[PdBr 2 (CH 2 Ph)(P(OPh) 3 )][PhCH 2 NEt 3 ] ( 1 ) and [PdBr(CH 2 Ph)(P(O-o-MeC 6 H 4 ) 3 )] 2 ( 2a ), were obtained in one-step syntheses from PdCl 2 (P(OPh) 3 ) 2 or PdCl 2 [P(O-o-MeC 6 H 4 ) 3 )] 2, NEt 3, and benzyl bromide and X-ray characterized. The air oxidation of complex 1 led to [PdBr 3 (P(OPh) 3 )][PhCH 2 NEt 3 ] ( 4 ) with the abstraction of benzaldehyde.