Heteroleptic (NHC/MIC) Biscarbene Ag(I) and Au(I) Complexes: Synthesis, Characterization and Catalytic Applications

A series of hetero-biscarbene silver(I) and gold(I) complexes of the general formula [NHC-M-MIC]PF6 (NHC=imidazol-2-ylidene, MIC=1,2,3-triazol-5-ylidene) have been prepared via the treatment of NHC-M-Cl precursors in reaction with an in situ generated mesoionic carbene (MIC). The new heteroleptic complexes have been fully characterized including NMR spectroscopy, elemental analysis, melting points and single crystal X-ray diffraction. The silver(I) derivatives were employed successfully in the solvent free KA2 (ketone-alkyne-amine) coupling for the preparation of a series of quaternary carbon-containing propargyl amines while, the gold(I) biscarbenes, demonstrated a good performance in the A3 (aldehyde, amine, alkyne) coupling and the benzylic oxidation processes under low catalyst loadings.