Hydrothermal synthesis and structural characterization of a family of lanthanide tartrates: [Ln 2(C 4H 4O 6) 3(H 2O) 3]·1.5H 2O (Ln = La, Ce, Pr, Nd, Sm)

Abstract

Coordination polymers containing lanthanides with tartaric acid [Ln 2(C 4H 4O 6) 3(H 2O) 3]·1.5H 2O (Ln = La, Ce, Pr, Nd, Sm and C 4H 4O 6 = d(−) or l(+) tartrate anion) have been synthesized using hydrothermal techniques and characterized by single crystal X-ray diffraction. The compounds are all isotypic with a monoclinic crystal system in the P2 1/ n space group. The asymmetric units of coordination polymers contain two metal centers having different coordination environments. One metal is bonded to four tartrate groups having three d and one l isomers (or three l and one d isomers), whereas the other metal is bonded to five tartrate groups having two d and three l isomers (or two l and three d isomers). Each trivalent metal center is coordinated to nine oxygen atoms that originate from carboxylate and hydroxyl groups of the tartrate anions and water molecules. These new polymers have three-dimensional structures containing open channels that are occupied by non-coordinating water molecules. Thermogravimetric and differential thermal analyses and adsorption of nitrogen have also been studied for these compounds.