Mechanochemical synthesis of new coordination polymers with acetylenedicarboxylate as bridging ligand
Résumé
CaADC (1) and Mg(ADC)(H2O)2 (2) were synthesized by grinding Ca(CH3COO)2 and Mg(CH3COO)2 · 4 H2O with acetylenedicarboxylic acid (H2ADC) in an agate mortar. After careful heating for two hours in an argon atmosphere at moderate temperatures – 50°C and 70°C, resp. – polycrystalline materials of good crystallinity were obtained. The crystal structures of 1 and 2 were solved and refined from X-ray powder diffraction data. In the course of the structural refinement it turned out that 1 and 2 are isotypic to SrADC (I41/amd, Z = 4) and Mn(ADC)(H2O)2 (I2/a, Z = 4). In both compounds metal cations are connected by bridging ADC2- ligands to form a 3D coordination network. Thermoanalytical investigations show that CaADC decomposes above 50°C, whereas for Mg(ADC)(H2O)2 a mass loss of approx. 33 % is observed above 150°C. The loss of one water molecule as well as a decarboxylation is very likely. The remaining residue is amorphous to X-rays.
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