Synthesis, characterization and DFT calculations of a novel hexanuclear silver(I) cluster-complex containing 4-ethyl-5-pyridin-2-yl-2,4-dihydro-[1,2,4]triazol-3-thione as a result from the cyclization of 2-pyridinformamide N-4-ethylthiosemicarbazone

Abstract: Reaction of 2-pyridine N-4 ethylthiosemicarbazone, HAm4E, with AgNO3 leads to the hexanuclear compound [Ag(E124tazt)]6 (1) (HE124tazt=4-ethyl-5-pyridin-2-yl-2,4-dihydro-[1,2,4]triazol-3-thione), the result of an oxidative cyclization of the starting thiosemicarbazone. All Ag atoms of [Ag(E124tazt)]6 are bridged through the six S atoms of the deprotonated E124tazt ligand to form two bridged Ag3S3 rings. Each silver atom exhibits a trigonal planar coordination geometry bonded to two thiolate S atoms and one N atom from the bidentate E124tazt ligand. The Ag⋯Ag distances are much shorter than the van der Waals’ radius sum for silver(I), suggesting binding interactions between the silver atoms, which were confirmed by means of DFT calculations. The X-ray single-crystal structural analysis reveals the arrangement of 1 as a two-dimensional (2D) network via π–π stacking interactions. Preliminary luminescence measurements have been carried out. [Copyright &y& Elsevier]