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]PF (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 KA (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 A (aldehyde, amine, alkyne) coupling and the benzylic oxidation processes under low catalyst loadings.

Expedient Synthesis of Highly Functionalized Abnormal Carbenegold(I) Complexes.

The reaction of 4-substituted imidazol-2-ylidenes with various electrophiles produces a series of 2,4-functionalized imidazolium salts. Subsequent metalation of these precursors using AuCl(SMe) provides the first examples of highly functionalized abnormal carbenegold(I) complexes. The present protocol introduces a new strategy for the synthesis of metallic abnormal carbenes featuring diverse functional groups.