C∧C* Platinum(II) Complexes with PtXPX Metallacycle Forming (X = N and S) Auxiliary Ligands: Synthesis, Crystal Structures, and Properties

The synthesis of cyclometalated NHC platinum­(II) complexes with two types of phosphorus-containing ligands is reported. Different synthetic approaches were utilized for each compound class. Dithiophosphinate and iminophosphonamide ligands form four-membered PtXPX metallacycles with coordination by either sulfur or nitrogen atoms (= X). The complexes are fully characterized, including two solid-state structures. Additionally, the photophysical and electrochemical properties were examined, and the results are rationalized by density functional theory calculations.