Synthesis and structure of coordination polymers of praseodymium(III) and erbium(III) with hydrogen maleate and benzene-1,3-disulfonate as linkers

Two new 1D coordination polymers [Pr(1,3-BDS)(HMA)(H2O)4] n and [Er(1,3-BDS)(HMA)(H2O)4] n (1,3-BDS = benzene-1,3-disulfonate and H2MA = maleic acid) having one-dimensional zigzag polymeric structure and containing praseodymium and erbium in +3 oxidation state were synthesized by solution synthesis method. The compositions and structures of coordination polymers were determined by elemental analysis, FT-IR, X-ray diffraction, and results of thermal decomposition. Coordination polymers [Pr(1,3-BDS)(HMA)(H2O)4] n and [Er(1,3-BDS)(HMA)(H2O)4] n are isomorphous and contain distorted square antiprism geometry around metal ion. Two molecules of benzene-1,3-disulfonate and hydrogen maleate coordinate to each metal ion in unidentate bridging mode to generate a linear zigzag polymeric chain. Four water molecules are also coordinated to each metal ion. Hydrogen bonded interaction involving water molecules, carboxylate and sulfonate groups of adjacent polymer chains lead to two-dimensional polymer expansion. The polymers are thermally robust as is indicated by thermal studies.