Phosphorescent Cyclometalated Platinum(ii) Hexahydroimidazo[1,5-a]pyridinylidene Complexes

The synthesis of N-heterocyclic carbene precursors based on the hexahydroimidazo[1,5-a]pyridine and their corresponding cyclometalated platinum(II) carbene complexes is reported. All compounds are fully characterized by standard techniques and additionally X-ray structures could be obtained for three complexes. The photophysical properties of these platinum complexes were investigated by absorption and photoluminescence measurements. All complexes showed strong phosphorescence at room temperature in the sky-blue area with quantum yields of up to 71 %. Additionally, their electrochemical properties were examined by voltammetry experiments. All results were rationalized by quantum chemical DFT calculations (PBE0/6-311G*).