Crystal structure of poly[[di-μ(3)-acetato-tetra­aqua­bis­(μ(2)-cyclo­hexane-1,4-di­carboxyl­ato)dilanth­an­um(III)] dihydrate]

The title compound, {[La(2)(CH(3)COO)(2)(C(8)H(10)O(4))(2)(H(2)O)(4)]·2H(2)O}(n) or [La(2)(ac)(2)(e,a-cis-1,4-chdc)(2)(H(2)O)(4)]·2H(2)O, 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-chdc(2−) 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 μ(3)-η(2):η(2) coordination mode of the bridging acetate group and the flexible di­carboxyl­ate fragments of 1,4-chdc(2−) 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.