Discrete Singular Metallophilic Interaction in Stable Large 12-Membered Binuclear Silver and Gold Metallamacrocycles of Amido-Functionalized Imidazole and 1,2,4-Triazole-Derived N-Heterocyclic Carbenes.

Metallophilic interactions were observed in four pairs of 12-membered metallamacrocyclic silver and gold complexes of imidazole-derived N-heterocyclic carbenes (NHCs), [1-(R)-3-N-(2,6-di-(R)-phenylacetamido)-imidazol-2-ylidene]M [R = -MeCH, R = Me, M = Ag () and Au (); R = Me, R = -Pr, M = Ag () and Au (); R = Et, R = -Pr, M = Ag () and Au ()], and a 1,2,4-triazole-derived N-heterocyclic carbene (NHC), [1-(-Pr)-4-N-(2,6-di-(-Pr)-phenylacetamido)-1,2,4-triazol-2-ylidene]M [M = Ag () and Au ()]. The X-ray diffraction, photoluminescence, and computational studies indicate the presence of metallophilic interactions in these complexes, which are significantly influenced by the sterics and the electronics of the N-amido substituents of the NHC ligands. The argentophilic interaction in the silver - complexes was stronger than the aurophilic interaction in the gold - complexes, with the metallophilic interaction decreasing in the order > > > > > > > . The - complexes were synthesized from the corresponding amido-functionalized imidazolium chloride - and the 1,2,4-triazolium chloride salts upon treatment with AgO. The reaction of - complexes with (MeS)AuCl gave the gold - complexes.