Thiazolo[5,4-d]thiazole-2,5-dicarboxylic acid, C6H2N2O4S2, and its coordination polymers

Thiazolo[5,4-d]thiazole-2,5-dicarboxylic acid, C6H2N2O4S2, was isolated as a polycrystalline material, and its crystal structure was determined by ab-initio X-ray powder diffraction (XRPD) methods. This species, upon deprotonation, was subsequently used in preparing the new coordination polymers Ag-2(C6N2O4S2), Mn(C6N2O4S2)(H2O)(2), Co(C6N2O4S2)(H2O)(2), Cu(C6N2O4S2)(H2O) and Zn(C6N2O4S2)(H2O)(2), fully characterized by analytical, thermal and XRPD structural methods - including in situ thermodiffractometry and simultaneous TGA and DSC. In the first-row transition metal derivatives, the [C6N2O4S2](2-) anion systematically prefers the N,O-chelating, vs. the expected O,O'-bridging, coordination mode, not allowing the formation of porous 3D frameworks. Indeed, these species are dense 1D coordination polymers. At variance, the silver derivative possesses a complex, dense 3D framework, due to the presence of mu(6)-[C6N2O4S2](2-) ligands showing two us-bridging carboxylates and two monohapto N-donor sites. When dehydration is viable, materials of E-n(C6N2O4S2) formulation are irreversibly recovered (n = 1 for E = Mn, Co, Zn, Cu; n = 2, for E = H). (C) 2010 Elsevier Masson SAS. All rights reserved.