Figure 3.

Crystal structure of [Zr(C₁₇H₂₁N₄O₆)]₂O - 8 H₂O (Zr-PCTA). (Left) The seven coordinate monomers are bridged by one oxygen atom, which lies on the crystallographic 2-fold axis at ½, y, ¼ in the unit cell, to fulfill Zr⁴⁺ ion’s requirement of an octa-coordinate ligand sphere. (Right) The monomer is depicted so that the coordination sphere around the Zr⁴⁺ ion is visualized more easily. Nitrogen one (N1) represents the nitrogen atom of the pyridyl ring. Only a partial numbering scheme is provided. Solvent molecules and hydrogen atoms are omitted for clarity. Thermal ellipsoids are drawn at the 50% probability level. The molecules are labeled to facilitate the identification of the symmetry related atoms only.