Tetranuclear Mn II /Zn II and Novel Azido-Bridged Chair-Shaped Heptanuclear Cd II Compounds: The Effect of Metal Ion and Coordination Mode of the Azide Group on the Structure of the Products

We report two tetranuclear compounds [MnL(N3)]4 (1), [Zn4L4(N3)2][Zn(N3)4]·3H2O (2) and a novel heptanuclear cluster [Cd7L6(N3)6](NO3)1.33(N3)0.66·12H2O (3) where L is a hydrazone Schiff base ligand based on pyridine. The ligand acts as a negatively charged tetradentate N3O-donor ligand and coordinates to the metal centers in the enolic form in 1–3. However, in compound 2, the ligand coordinated to the ZnII ion in the two different coordination modes. Metal centers in 1 and 2, bridged by the organic ligand form tetranuclear metal organic complexes and the N3 – anion acts as terminal ligand. In compound 3, N3 – acts as bridging ligand to the cadmium(II) centers, and form a rare heptanuclear cluster with an interesting chair conformation. The latter compound is a novel azido-bridged chair-shaped heptanuclear CdII cluster that guides the formation of a water hexamer in the solid state. It acts as a robust binding block in the recognition of nitrate. The ability of the water hexamer to bind anions has been analyzed using DFT calculations and several computational tools.