Crystal structure of poly[[di-μ3-acetato-tetraaquabis(μ2-cyclohexane-1,4-dicarboxylato)dilanthanum(III)] dihydrate]

Abstract

The title compound, {[La2(CH3COO)2(C8H10O4)2(H2O)4]·2H2O}n or [La2(ac)2(e,a-cis-1,4-chdc)2(H2O)4]·2H2O, where ac is acetate and 1,4-chdc is cyclohexane-1,4-dicarboxylate anion, is a binuclear lanthanum(III) complex. Each metal atom is decacoordinated by four O atoms from two distinct 1,4-chdc2− ligands, four O atoms from three acetate groups and two O atoms from coordinated water molecules to form a distorted bicapped square-antiprismatic geometry. Two non-coordinated water molecules are also present in the formula unit. The most remarkable feature of this compound is that it possesses a only cis conformation for cyclohexane-1,4-dicarboxylic acid, although the raw material consists of a mixture of cis and trans isomers. The μ3-η2:η2 coordination mode of the bridging acetate group and the flexible dicarboxylate fragments of 1,4-chdc2− results in the formation of infinite two-dimensional lanthanide–carboxylate layers within the crystal structure. The directionality of strong intermolecular O—H...O and weak C—H...O interactions provides robustness to the layers, which leads to the construction of a three-dimensional supramolecular network. The crystal studied was refined as a two-component twin.

Keywords

• crystal structure
• cyclohexane-1,4-dicarboxylic acid
• lanthanum(III) complex