An Unusual Palladium Complex Involved in an Unusual Rearrangement of Ortho-Palladated Aryldithioacetals

The reaction of 1 with Pd(dba)₂, Tl(TfO) and PPh₃ in 1:1:1:2 molar ratios to give 3 implicates (i) an oxidative addition reaction, (ii) a rearrangement involving the cleavage of one HC−S bond and formation of an aryl-S bonds, and (iii) coordination of the Pd(PR₃)₂ group with a ligand intermediate between η²-[ArCHS⁽⁺⁾To] and κ²-C,S-ArCH^(-)STo, which requires the consideration of 3 as intermediate between a Pd(0) and a Pd(II) complex. The coordination of the ligand as a chelating three-membered ring, instead of the expected five-membered ring involving C(10) and S(1), and the partial intramolecular redox process are explained as a consequence of the transphobia of the pair of ligands Ph₃P/CH(STo)Ar.