Synthesis and Crystal Structure of Three Alkaline Earth Coordination Compounds Based on 1,2,5-Thiadiazole-3,4-Dicarboxylic Acid Ligand

1,2,5-thiadiazole-3,4-dicarboxylic acid (H2 tdzdc) ligand has been used to construct three coordination compounds [Mg(tdzdc)(H2O)4](1), [Ca(tdzdc)(H2O)2]n(2) and [Sr(tdzdc)(H2O)3]n(3) by the solvothermal reaction. Single-crystal structure analyses reveal a mononuclear coordination structure for compound 1 and two dimensional coordination structure both for compound 2 and 3. Furthermore, all of these three compounds comprise any amount of hydrogen bond interactions, which extends their crystal structure into three dimensional (3D) frameworks. Different crystal structure of compounds 1–3 reveals diversified coordination modes of H2 tdzdc ligand toward alkaline earth metal ions, depending mainly on the radius and the electron shell number of metal ions used. Based on 1,2,5-thiadiazole-3,4-dicarboxylic acid (H2 tdzdc) ligand, three new alkaline earth metal compound were synthesized with different structure.