Crystal structure of polydi-μ3-acetato-tetra­aqua­bis­(μ2-cyclo­hexane-14-di­carboxyl­ato)dilanth­an­um(III) dihydrate

摘要

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.