Phosphorescent Cyclometalated Platinum(II) Imidazolinylidene Complexes

Abstract

We present the synthesis and characterization of six novel bidentate (Formula presented.) cyclometalated platinum(ii) complexes derived from saturated N-heterocyclic carbene precursors, namely 1-aryl-3-methyl-1H-4,5-dihydroimidazolium salts. The title compounds were then synthesized by a multi-step reaction, which includes an in situ generation of the silver carbene complex, followed by transmetalation to platinum and subsequent introduction of the β-diketonate ligand. Structural characterization by NMR experiments and solid-state structures prove the cyclometalation and the saturated backbone of the NHC motif. Photophysical and electrochemical properties of the platinum(ii) complexes were examined and studied in detail by DFT calculations. The title compounds are strongly emissive at room temperature in the sky-blue region of the visible spectrum and show quantum yields of up to 71 % in a PMMA matrix.