Nickel(II) complexes with novel nitron-type NHC ligands: synthesis and catalytic activity in the Suzuki–Miyaura coupling of aryl chlorides

A new method has been developed for synthesizing nitron-type 1,4-dyaryl-3-arylamino-1,2,4-triazolium salts through a stepwise reaction of N,N'-diarylcarbodiimides with aryl hydrazines, trimethyl orthoformate and Me₃SiCl. These salts have been utilized as NHC-proligands to prepare novel (NHC)₂NiCl₂ and (NHC)NiCpCl (Cp = cyclopentadienyl anion) complexes. Catalytic trials of these complexes uncovered a highly effective catalyst for the Suzuki–Miyaura cross-coupling of non-activated aryl chlorides.