Unexpected formation of an ortho-palladated diphenylthioether

The reaction of [Ph 4 P][BrC 6 H 4 S-2] with [Pd 2 (dba) 3 ].dba (dba = dibenzylideneacetone) in the presence of PPh 3 gives trans-[Pd(C 6 H 4 SPh-2)Br(PPh 3 ) 2 ]. A sequence of reactions consisting of oxidative addition of the tetraphenylphosphonium cation to palladium(0), reductive C-S coupling to give BrC 6 H 4 SPh-2, and, again, an oxidative addition of the latter to palladium(0) seems to constitute the pathway for the formation of the final palladium complex. Some experimental evidence supporting this pathway is provided. The crystal structure of trans-[Pd(C 6 H 4 SPh-2)Br(PPh 3 ) 2 ] has been solved by an X-ray diffraction study.