A four-coordinate Cu(I)–N-heterocyclic carbene complex: Synthesis, structure, properties, and application in amination for the synthesis of 1-(2-N-heteroaryl)-1H-pyrazoles

Abstract

A new luminescent, cationic, heteroleptic, four-coordinate Cu(I)– N-heterocyclic carbene complex [Cu(Br-Pyim)(POP)](PF6) is successfully prepared and characterized, where Br-Pyim and POP are 1-(6-bromopyridin-2-yl)imidazole-3-benzyl-2-ylidene and bis[2-(diphenylphosphino)phenyl]ether, respectively. Its detailed structure is determined by single-crystal X-ray analysis. It exists as a crystalline powder at room temperature and exhibits bright yellow-green emission. The use of the Cu(I)– N-heterocyclic carbene complex as a catalyst for amination reactions is also investigated and is found to be very efficient for the amination of 2- N-heteroaryl chlorides with pyrazoles, giving the desired substituted 1-(2- N-heteroaryl)-1 H-pyrazoles in good yields.