Crystal structure of a mixed-ligand terbium(III) coordination polymer containing oxalate and formate ligands, having a three-dimensional fcu topology

The title compound, poly[(μ (3)-formato)(μ (4)-oxalato)terbium(III)], [Tb(CHO(2))(C(2)O(4))](n), is a three-dimensional coordination polymer, and is isotypic with the La(III), Ce(III) and Sm(III) analogues. The asymmetric unit contains one Tb(III) ion, one formate anion (CHO(2) (−)) and half of an oxalate anion (C(2)O(4) (2−)), the latter being completed by application of inversion symmetry. The Tb(III) ion is nine-coordinated in a distorted tricapped trigonal–prismatic manner by two chelating carboxyl­ate groups from two C(2)O(4) (2−) ligands, two carboxyl­ate oxygen atoms from another two C(2)O(4) (2−) ligands and three oxygen atoms from three CHO(2) (−) ligands, with the Tb—O bond lengths and the O—Tb—O bond angles ranging from 2.4165 (19) to 2.478 (3) Å and 64.53 (6) to 144.49 (4)°, respectively. The CHO(2) (−) and C(2)O(4) (2−) anions adopt μ (3)-bridging and μ (4)-chelating-bridging coordination modes, respectively, linking adjacent Tb(III) ions into a three-dimensional 12-connected fcu topology with point symbol (3(24).4(36).5(6)). The title compound exhibits thermal stability up to 623 K, and also displays strong green photoluminescence in the solid state at room temperature.