Cyclopalladated Complexes of 3-Thiophosphorylbenzoic Acid Thioamides: Hybrid Pincer Ligands of a New Type. Synthesis, Catalytic Activity, and Photophysical Properties

Treatment of the 3-diphenylphosphorylbenzoic acid amides 3a, b with the Lawesson reagent resulted in 3-diphenylthiophosphorylbenzoic acid thioamides 4a, b, which easily underwent cyclopalladation at the C-2 position of the central benzene ring to give new hybrid pincer complexes 5a, b with κ 3 -SCS coordination. Molecular structures of the complexes were characterized by X-ray diffraction. The peculiarities of chemical bonding in 5a were investigated via topological analysis of charge density in the crystal. The palladium complexes 5a, b demonstrated high catalytic activity for the Suzuki cross-coupling reactions of aryl bromides with phenylboronic acid and exhibited luminescence at 77 and 300 K.