New Coordination Polymers of Zinc(II), Copper(II) and Cadmium(II) with 1,3-Bis(1,2,4-triazol-4-yl)adamantane

The new coordination polymers (CPs) [Zn(tr(2)ad)Cl-2](n), {[Cu(tr(2)ad)Cl]Cl center dot 4H(2)O}(n), [Cd-2(tr(2)ad)Cl-4](n), {[Cu(tr(2)ad)(NO3)](NO3)}(n) and {[Cd(tr(2)ad)(NO3)](NO3)center dot H2O}(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 (tr(2)ad). Investigation of the thermal behaviour assessed the thermal stability of these CPs, with [Cd-2(tr(2)ad)Cl-4](n) starting to decompose only around 365 degrees C. As retrieved by powder X-ray diffraction, while [Zn(tr(2)ad)Cl-2](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 tr(2)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(tr(2)ad)Cl-2](n) is the first Zn-II-based CP containing the tr(2)ad spacer.