Syntheses and crystal structures of the cerium-based coordination polymers poly[(acetic acid)bis-(μ-5-carb-oxy-thio-phene-2-carboxyl-ato)bis-(μ-thio-phene-2,5-di-carboxyl-ato)dicerium(III)] and poly[(μ-acetato)-aqua-(μ(4)-thio-phene-2,5-di-carboxyl-ato)cerium(III)].

The title compounds, [Ce(2)(C(6)H(3)SO(4))(2)(C(6)H(2)SO(4))(2)(CH(3)COOH)] (n) (1) and [Ce(CH(3)COO)(C(6)H(2)SO(4))(H(2)O)] (n) (2) were synthesized by solvothermal reaction of Ce(NO(3))(3)·6H(2)O with 2,5-thio-phenedi-carb-oxy-lic acid (H(2)TDC, C(6)H(4)SO(4)) and acetic acid in aceto-nitrile or ethanol/water, respectively. These compounds were obtained as single crystals among other crystalline phases. Both compounds belong to the family of three-dimensional coordination polymers. The asymmetric unit of 1 consists of two Ce(III) cations, two TDC(2-) dianions, two HTDC(-) anions and one acetic acid ligand, all of them located in general positions. The two Ce(III) cations are each coordinated by eight oxygen atoms in the form of distorted square anti-prisms. These are bridged by carboxyl-ate and carb-oxy-lic acid groups, forming mono-periodic hybrid inorganic building units (IBUs), which are connected into a three-dimensional network by the TDC(2-) and HTDC(-) ligands. Compound 2 has an asymmetric unit composed of one Ce(III) cation, one TDC(2-) dianion, one acetate anion and one water mol-ecule in general positions. The cerium atom is eightfold coordinated by oxygen atoms. Edge-sharing CeO(8) polyhedra form a dinuclear IBU (Ce(2)O(14)). This IBU is bridged by six TDC(2-) linkers to nine other IBUs, forming a three-dimensional framework. Both title compounds exhibit additional O-H⋯O hydrogen bonds. Powder X-ray diffraction shows that both compounds were not obtained as pure phases.