Neutral Binuclear Ag(I) and Au(I) N‐Heterocyclic Carbene Complexes of Axially Chiral and Racemic Scaffolds: Synthesis and Characterization

Neutral bimetallic silver(I) and gold(I) complexes of N‐ heterocyclic carbene ligands derived from racemic biphenyl and axially chiral binapthyl frameworks have been synthesized and structurally characterized. In particular, the neutral bimetallic silver(I) complexes of the type {L(NHC)2M2} (M=Ag, Au) [L=2,2′‐dioxo‐biphenyl, NHC=1‐methyl‐3‐(‐2‐phenyl‐acetamido)‐imidazol‐2‐ylidene (1 f); L=2,2′‐dioxo‐binapthyl, NHC=1‐methyl‐3‐(‐2‐phenyl‐acetamido)‐imidazol‐2‐ylidene (2 e)] are synthesized from the corresponding imidazolium chloride salts (1‐2)d by the reaction with Ag2O in quantitative yields. The gold(I) complexes are synthesized by the transmetallation of their corresponding {L(NHC)2}Ag2 complexes. Quite interestingly, a weaker argentophilic interaction was observed in the solid state X‐ray crystalllographic structure of binapthyl derivative 2 e, as Ag⋅⋅⋅Ag contact of 3.3011 Å while in case of biphenyl derivative 1 f there is no such aurophilic interaction exhibited a significant Au⋅⋅⋅Au contact. Racemic‐biphenyl and axially chiral‐binapthyl derived, N‐heterocyclic carbene silver(I) and gold(I) complexes are synthesized and structurally characterized. 17‐Membered Macrometalla‐bi‐cyclic X‐ray structures of {L(NHC)2}M2 (M=Ag, Au) type late transition metal complexes of biphenol (1 f) and BINOL (2e) scaffolds with N/O function are neutral, bimetallic and iso‐structural to each other.