Abstract
Metallophilic interactions were observed in four pairs of 12-membered metallamacrocyclic silver and gold complexes of imidazole-derived N-heterocyclic carbenes (NHCs), [1-(R(1))-3-N-(2,6-di-(R(2))-phenylacetamido)-imidazol-2-ylidene](2)M(2) [R(1) = p-MeC(6)H(4), R(2) = Me, M = Ag (1b) and Au (1c); R(1) = Me, R(2) = i-Pr, M = Ag (2b) and Au (2c); R(1) = Et, R(2) = i-Pr, M = Ag (3b) and Au (3c)], and a 1,2,4-triazole-derived N-heterocyclic carbene (NHC), [1-(i-Pr)-4-N-(2,6-di-(i-Pr)-phenylacetamido)-1,2,4-triazol-2-ylidene](2)M(2) [M = Ag (4b) and Au (4c)]. 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 1b-4b complexes was stronger than the aurophilic interaction in the gold 1c-4c complexes, with the metallophilic interaction decreasing in the order 4b > 1b > 1c > 4c > 3b > 3c > 2b > 2c. The 1b-4b complexes were synthesized from the corresponding amido-functionalized imidazolium chloride 1a-3a and the 1,2,4-triazolium chloride 4a salts upon treatment with Ag(2)O. The reaction of 1b-4b complexes with (Me(2)S)AuCl gave the gold 1c-4c complexes.