A new three-dimensional coordination polymer containing trans,trans,trans-cyclobutanetetracarboxylate and edge-sharing LaO₉ polyhedral chains

A novel three-dimensional open-framework La(H₂O)(Hcbtc^3-) (1) (H₄cbtc=1,2,3,4- cyclobutanetetracarboxylic acid) has been synthesized hydrothermally in basic aqueous solution. Its crystal structure was solved by single crystal X-ray diffraction, and characterized by powder X-ray diffraction, thermogravimetric analysis, FT-IR and elementary analysis. The structure of 1 consists of infinite edge-sharing LaO₈(H₂O) polyhedral chains along the [100] direction, connected by Hcbtc^3- along the [010] and [001] directions. The Hcbtc^3- in 1 has four interconnecting carboxylate groups of all trans conformations, which include one deprotonated carboxylates among the four carboxylate groups. The prepared lanthanum carboxylate polymer has high thermal stability up to 400°C and could be dehydrated at above 200°C at nitrogen atmosphere.