Synthesis, molecular structure, and photoluminescence properties of palladium and platinum complexes containing phosphine sulfide-based SCS pincer ligand

3,5-Bis(diphenylphosphinothioyl)toluene (1) was prepared by Pd-catalyzed aryl phosphination of 3,5-dibromotoluene with diphenylphosphine followed by sulfurization with elemental sulfur. Cyclometalation of 1 with K2MCl4 (M=Pd, Pt) occurred at the C-4 position of the central toluene ring and afforded new pincer complexes (2: M=Pd, 3: M=Pt). Molecular structures of the complexes were characterized by X-ray diffraction. The platinum complex 3 exhibits strong emission in the glassy frozen state as well as in the solid state.