Heteroleptic BIAN‐Based N‐Heterocyclic Carbene Cu(I) Complexes: Synthesis, Characterization, and Reactivity

A series of heteroleptic three‐coordinate Cu(I) complexes containing bis(imino)acenaphthene (BIAN)‐based N‐heterocyclic carbenes and dipyridylamine ligands has been synthesized. The complexes Cu(BIAN‐IPr)(Hdpa)PF 6 , 1 ; Cu(BIAN‐IPr)(3,3′‐Me 2 Hdpa)PF 6 , 2 ; Cu(BIAN‐IPr)(3,4′‐Me 2 Hdpa)PF 6 , 3 ; Cu(BIAN‐IPr)(3,5′‐Me 2 Hdpa)PF 6 , 4 ; Cu(BIAN‐IPr)(3,6′‐Me 2 Hdpa)PF 6 , 5 ; Cu(BIAN‐IMes)(Hdpa)PF 6 , 6 ; and Cu(BIAN‐IMes)(3,3′‐Me 2 Hdpa)PF 6 , 7 , wherein IPr = 1,3‐bis(2,6‐diisopropylphenyl)imidazole‐2‐ylidene and IMes = 1,3‐bis(2,4,6‐trimethylphenyl)imidazol‐2‐ylidene, have been characterized by 1 H and 13 C NMR spectroscopies, elemental analysis, CV, and X‐ray crystallography. The crystal structure data indicated a mononuclear copper(I) center bound to both NHC and HDPA ligands, with all complexes adopting a three‐coordinate geometry. The UV–vis absorption spectra of complexes 2–7 displayed a strong ligand‐centered absorption band at approximately 300 nm, along with a weak mixed ligand‐ and metal‐centered charge transfer band around 420 nm. The complexes exhibited minimal or no solid‐state emission upon 340 nm excitation, unlike their non‐BIAN counterparts. Exploring the structural parameters and their relationship to the photoluminescent properties of these complexes rationalized the nonemissive behavior. The BIAN‐based Cu‐NHC complexes and their IPr analogs were shown to be moderately efficient catalysts in the Buchwald–Hartwig CN coupling of 2‐bromopyridine and 2‐aminopyridine derivatives, a reaction previously catalyzed by Pd 2 (dba) 3 .