Guest-containing supramolecular isomers of silver(i) 3,5-dialkyl-1,2,4-triazolates: syntheses, structures, and structural transformation behaviours

Abstract

An in-depth synthetic study for potential new supramolecular isomers of silver(I) 3,5-dialkyl-1,2,4-triazolates was carried out through liquid diffusion and rapid solution mixing of [Ag(NH₃)₂]OH and the related triazoles. Apart from the literature reported close-packing complexes of [Ag(dmtz)] (1a, Hdmtz = 3,5-dimethyl-1,2,4-triazole), [Ag(detz)] (2a, Hdetz = 3,5-diethyl-1,2,4-triazole), [Ag(dptz)] (3a, Hdptz = 3,5-dipropyl-1,2,4-triazole) and [Ag(diptz)] (4a, Hdiptz = 3,5-diisopropyl-1,2,4-triazole), four guest-containing isomers [Ag₅(detz)₅]·C₆H₆ (2b), [Ag₄(dptz)₄]·0.5C₆H₆ (3b), [Ag(diptz)]·0.5H₂O (4b) and [Ag(diptz)]·C₆H₆ (4c) were discovered. Single-crystal X-ray diffraction studies revealed that 2b, 3b and 4b are complicated coordination networks with small discrete cavities, while 4c possesses an nbo-a framework topology with large discrete cavities embedding a unique supramolecular hexamer of benzene guest molecules with an orthogonal arrangement. Single-crystal and powder X-ray diffraction as well as thermogravimetry studies showed that 2b and 3b can undergo reversible temperature- and guest-induced single-crystal-to-single-crystal structural transformations, respectively, in which the conformation changes of the flexible alkyl groups play important roles. On the other hand, single crystals of 4c can transform into single crystals of another new isomer [Ag₈(diptz)₈]·C₆H₆·CH₃OH (4d) with a completely different network connectivity, by immersing in methanol.