Synthesis, crystal structures and reactivity of copper(I) amidate complexes with aryl halides: insight into copper(I)-catalyzed Goldberg reaction

In this paper, copper(I) amidate complexes (2-3), proposed intermediates in copper-catalyzed Goldberg reaction, have been prepared and characterized by elemental analysis, IR, (1)H NMR and X-ray crystallography. Ancillary ligand bis(diphenylphosphino)ferrocene (dppf) has contributed greatly to the stability of the copper-amidate complexes due to its strong chelating ability and weak intermolecular interactions. Thermal gravimetric analyses are carried out to determine the thermal competency of complexes 2-3 as the intermediates of the high-temperature Goldberg reactions. Reaction of complexes 2 and 3 with aryl halides generates the N-arylation products 5-8, accompanied by the formation of a copper(I) complex Cu(dppf)X (X = I or Br) 4, which has been determined by LC-MS analysis. These results provide new evidence for the mechanism of copper(I)-catalyzed Goldberg reaction.