Red photo- A nd electroluminescent half-lantern cyclometalated dinuclear platinum(II) complex

New cyclometalated dinuclear platinum(II) complex bearing bridged 4,6-dimethylpyrimidine-2(1H)-thiolate (μ-C₆H₇N₂S-κN,S) ligands, [{Pt(ppy)(μ-C₆H₇N₂S-κN,S)}₂] (3) (ppy=(2-phenylpyridinato-C²,N)) was prepared via the reaction of chloro-bridged dimer [{Pt(ppy)Cl}₂] with 4,6-dimethylpyrimidine-2(1H)-thione (C₆H₈N₂S) in the presence of t-BuOK. The complex holds dinuclear frameworks with short Pt(II)···Pt(II) distance (2.8877(3) Å), and exhibit red intense luminescence from the triplet metal-metal-to-ligand charge-transfer at 697 nm in CH₂Cl₂ solution and at 649 nm in solid state at RT. Single crystal XRD analysis reveals the metallophilic interactions Pt···Pt with significant covalent contribution in the structure of 3 which were studied by quasi-relativistic and relativistic DFT calculations (viz., M06/MWB60(Pt) and 6-311+G* (other atoms); M06/DZP-DKH levels of theory) and topological analysis of the electron density distribution within the framework of Bader’s theory (QTAIM method). Estimated strength of the Pt···Pt contact is 8.1–12.2 kcal/mol and it is mostly determined by crystal packing effects and weak attractive interactions between the adjacent metal centers due to overlapping of their d_z2 and p_z orbitals. An organic light-emitting diode based on this complex showed red electroluminescence with maximal luminance of 115 cd/m² and current efficiency of 2.45 cd/A at this luminance.