N-heterocyclic carbene adducts of cyclopalladated ferrocenylpyridine containing chloride or iodide anions: synthesis, crystal structures and application in the coupling of terminal alkynes with arylboronic acids

Two air-stable N-heterocyclic carbene (NHC) adducts of cyclopalladated ferrocenylpyridine containing chloride or iodide anions 2–3 have been easily prepared from the bridge-splitting reaction of the palladacyclic dimer 1 and anion exchange reaction, respectively. They were characterized by elemental analysis, IR, ¹H, and ¹³C NMR. Additionally, the structures of these complexes were determined by single-crystal X-ray analysis. These adducts have been successfully applied to the coupling of terminal alkynes with arylboronic acids under atmospheric conditions.