A New Family of Bimetallic Framework Materials Showing Reversible Structural Transformations

Abstract

Three new bimetallic framework compounds, namely, (([Cd 3 (tn) ). They have been characterized by IR, X-ray diffraction, elemental analysis and immersion calorimetry. All three compounds have three-dimensional structures, with both the organic ligand and the cyanide groups acting as bridges. Compounds 1 and 3 have channels occupied by water molecules of crystallization. All three complexes are stable indefinitely when exposed to the air at room temperature; however, when compounds 1 and 3 are heated, they lose the water molecules of crystallization. The powder X-ray diffractograms of these dried and as yet unknown species are different from those of the original compounds. However, in a humid atmosphere both dried compounds readsorb water molecules and revert to the original structures, as shown by powder X-ray diffraction measurements. The adsorption properties of compounds 1 and 3 were studied using immersion calorimetry and in situ powder X-ray diffraction. In the case of compound 3 the heat of the structural transformation on rehydration was found to be ca. 19 ( 3 J/g.