New coordination polymers of zinc(Ii), copper(ii) and cadmium(ii) with 1,3-bis(1,2,4-triazol-4-yl)adamantane

Abstract

The new coordination polymers (CPs) [Zn(tr2 ad)Cl2 ]n, {[Cu(tr2 ad)Cl]Cl·4H2 O}n, [Cd2 (tr2 ad)Cl4 ]n, {[Cu(tr2 ad)(NO3)](NO3)}n and {[Cd(tr2 ad)(NO3)](NO3)·H2 O}n were obtained in the form of air-and moisture-stable microcrystalline powders by the solvothermal reactions of zinc(II), copper(II) and cadmium(II) chlorides or nitrates with the ligand 1,3-bis(1,2,4-triazol-4-yl)adamantane (tr2 ad). Investigation of the thermal behaviour assessed the thermal stability of these CPs, with [Cd2 (tr2 ad)Cl4 ]n starting to decompose only around 365◦ C. As retrieved by powder X-ray diffraction, while [Zn(tr2 ad)Cl2 ]n features 1-D chains along which the metal centre shows a tetrahedral geometry and the spacer is exo-bidentate, the other CPs contain 2-D double-layers in which the metal ions possess an octahedral stereochemistry and the linker is exo-tetradentate. A comparative structural analysis involving known coordination compounds containing the tr2 ad ligand enabled us to disclose (i) the versatility of the ligand, as far as the coordination modes are concerned; (ii) the variability in crystal structure dimensionality, ranging from 1-D to 3-D; (iii) the fact that, to the best of our knowledge, [Zn(tr2 ad)Cl2 ]n is the first ZnII-based CP containing the tr2 ad spacer.