Coinage metal complexes of N‐heterocyclic carbene bearing nitrile functionalization: Synthesis and photophysical properties

Abstract

A new series of N‐heterocyclic carbene (NHC) ligand precursors (1 and 2) with their [Ag(I)(NHC)2]PF6 complexes (3 and 4) and [ClAu(I)(NHC)] complexes (5 and 6) are reported. Complexes 5 and 6 were synthesized via transmetalation reaction using either 3 or 4 and AuCl(SMe2) as reactants, respectively. All the synthesized compounds were fully characterized using elemental analyses and Fourier transform infrared, 1H NMR and 13C NMR spectroscopies. In the crystal structures of 3, 5 and 6, the Ag(I) and Au(I) ions are in a linear geometry. The entire structure of 3 is stabilized by significant π–π interactions, while the structures of 5 and 6 are stabilized with the presence of aurophilic interactions between the adjacent Au(I) ions as well as CH–π or π–π interactions. From photoluminescence studies, complexes 5 and 6 show dual‐emission characteristics. The higher‐energy fluorescence originates from 1XLCT mixed with 1MLCT, while the lower‐energy phosphorescence is ascribed to 3XLCT and 3MLCT with small contribution of 3ILCT, as evidenced by density functional theory (DFT) and time‐dependent DFT calculations of the modelled molecules.