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 > > > > > > > .

One pot tandem dehydrogenative cross-coupling of primary and secondary alcohols by ruthenium amido-functionalized 1,2,4-triazole derived N-heterocyclic carbene complexes.

One-pot tandem dehydrogenative cross-coupling of primary and secondary alcohols was catalyzed by three ruthenium complexes [1-()-4--(furan-2-ylmethyl)acetamido-1,2,4-triazol-5-ylidene]Ru(-cymene)Cl [R = Et (1b), i-Pr (2b), Bn (3b)], of amido-functionalized 1,2,4-triazole derived N-heterocyclic carbene (NHC) ligands. Density Functional Theory (DFT) calculations were employed for the ruthenium (1b) precatalyst to understand this reaction mechanism completely, and the mechanisms adapted are divided categorically into three steps (i) nucleophilic substitution of chloride ions by alcohols, (ii) dehydrogenation of primary and secondary alcohols, and (iii) olefin and ketone hydrogenation. Our mechanistic study reveals that the formation of a deprotonated Ru-alcoholate (A) or (E) intermediate is favorable compared to the protonated form (A') or (E') from (1b) by associative nucleophilic substitution.