Structurally different cadmium(II) and lead(II) supramolecular polymers with the same benzene-1,2,3,4-tetracarboxylate dianion as bridging ligands from hydrothermal reactions

Two crystalline metal-organic frameworks, [Cd2(o-BTC)(H2O)2]n (1) and [Pb2(o-BTC)]n (2) (o-BTC = benzene-1,2,3,4-tetracarboxylic), were synthesized under hydrothermal conditions and characterized by analytical, spectroscopic and single crystal X-ray diffraction studies, which reveal three-dimensional reticular structures via M2+ and carboxylate ligands. All carboxyl groups of o-BTC are deprotonated, in agreement with the IR data. The Cd2+ centers of 1 have one coordination environment, while Pb2+ centers of 2 have two coordination environments. Both 1 and 2 form 3D interpenetrated grid structures along the b and c axes, respectively.