5,6‐ and 6,6‐Membered Palladium(II) Pincer Complexes Based on Functionalized Carboxamides with Ancillary Sulfur and Nitrogen Donors

New multidentate ligands have been synthesized by the condensation of 2‐(methylsulfanyl)benzoyl chloride with a range of amines bearing ancillary N or S donors. In reactions with PdCl₂(NCPh)₂, the ligands smoothly underwent direct cyclopalladation to give pincer complexes with 5,6‐ or 6,6‐membered fused metallocycles. The oxidation of the sulfide ligands with H₂O₂ afforded the corresponding sulfoxide derivatives, which readily formed analogous pincer complexes with the Pd^II ions. The realization of κ³‐S,N,X coordination (X = N or S) was confirmed by multinuclear NMR and IR spectroscopic data and, in some cases, X‐ray crystallography. An unusual dynamic behavior of the 6,6‐membered S,N,S complex with an organophosphorus ligand was additionally studied by the ROESY technique. All of the palladocycles obtained were tested as precatalysts for the Suzuki cross‐coupling of aryl bromides with arylboronic acids, which allowed us to evaluate the main structure–activity relationships.