Figure 2.

Crystal structure of 2: (a) the dinuclear {Cd₂} secondary building unit, showing the coordination sphere of the Cd(II) center, (b) the coordination mode of 1,4-ndc²⁻ ligand, (c) polyhedral representation of the Cd₂ SBU, (d) schematic representation of the topological 6-connected node, (e) polyhedral and schematic representations of the two-dimensional [Cd₂(1,4-ndc)₂]_n layer, showing the sql topology, (f) polyhedral and schematic representations of the three-dimensional bipillared-layer framework showing the pcu topology, (g) polyhedral and schematic representations of the 2-fold interpenetrating pcu nets.