Hydrothermal synthesis and crystal structure of a new lanthanum(III) coordination polymer with fumaric acid

The title compound, poly[diaquatris(μ 4 -but-2-enedioato)(μ 2 -but-2-enedioic acid)dilanthanum(III)], [La 2 (C 4 H 2 O 4 ) 3 (C 4 H 4 O 4 )(H 2 O) 2 ] n , was synthesized by the reaction of lanthanum chloride pentahydrate with fumaric acid under hydrothermal conditions. The asymmetric unit comprises an La III cation, one and a half fumarate dianions ( L 2− ), one a half-molecule of fumaric acid (H 2 L ) and one coordinated water molecule. Each La III cation has the same nine-coordinate environment and is surrounded by eight O atoms from seven distinct fumarate moieties, including one protonated fumarate unit and one water molecule in a distorted tricapped trigonal–prismatic environment. The LaO 8 (H 2 O) polyhedra centres are edge-shared through three carboxylate bridges of the fumarate ligand, forming chains in three dimensions to construct the MOF. The crystal structure is stabilized by O—H...O hydrogen-bond interactions between the coordinated water molecule and the carboxylate O atoms, and also between oxygen atoms of fumaric acid