Syntheses, structures and properties of coordination polymers of cadmium(ii) with 4-methyl-1,2,4-triazole-3-thiol ligand

Hydro(solvo)thermal reactions of cadmium(II) salts with 4-methyl-1,2,4-triazole-3-thiol (Hmptrz) afforded six novel cadmium(II) coordination polymers, namely, [Cd(mptrz)2]n (1), [Cd(mptrz)X]n (X = Br (2) and I (3)), [Cd(mptrz)(μ2-X)]n (X = Br (4) and Cl (5)), and [Cd3(μ3-OH)2(mptrz)4]n (6). Compound 1 is a 1D looped chain structure. Compounds 2 and 3 are isostructural and have 1D ladder structures. Compounds 4 and 5 are isomorphs and feature 2D layered structures. Cadmium(II) bromide formed 1D ladder of 2 and 2D layer of 4, representing an unusual example of Br bond isomerism. Compound 6 has a 1D tape structure with an uncommon 1D inorganic ⋯Cd2(μ3-OH)2–Cd–Cd2(μ3-OH)2⋯ chain. The structural diversity of these materials is reflected in the variety of coordination polyhedra displayed by the cadmium sites: tetrahedral; trigonal bipyramidal; octahedral. The solid state photoluminescence of all compounds have been investigated. However, only compound 6 exhibits photoluminescence with an emission maximum at 435 nm upon excitation at 346 nm. Solid-state density functional theory (DFT) calculations were performed on compound 6. In addition, these compounds were characterized by IR, elemental analysis, and thermogravimetric analysis.