(Benzimidazolin‐2‐ylidene)–AuI–Alkynyl Complexes: Syntheses, Structure, and Photophysical Properties

Abstract A series of N‐heterocyclic carbene‐based Au I –σ‐acetylide complexes of the type [(Bimz)Au–C≡CR] (Bimz = benzimidazolin‐2‐ylidene; R = aryl, silyl groups) ( 1a – 1l , 2 , 3 ) were prepared from the precursor [(Bimz)Au I Cl] by an in situ deprotonation of the terminal alkynes. Steady‐state photoluminescence studies revealed that most of these complexes exhibit phosphorescence at room temperature and in 77 K rigidified matrices. Molecular structures were determined by single‐crystal X‐ray diffraction studies for complexes 1a , 1b , 1e , 1f , 1h , 1k , and 1l . Complexes 1f , 1h , and 1l revealed weak unsupported aurophilic interactions. Cyclic voltammetry studies exhibited irreversible behavior with one oxidation peak potential ( E p,a ) for most cases in the region 0.7–1.4 V. Experimental and DFT studies suggest that the nature of the emission is predominantly of intraligand character 3 IL(π–π*) with a slight perturbation from the metal.