Coordination polymers of tetrazole-yl acylamide with octahedrally coordinated divalent transition metals: the effects of metal centers and side-groups on the structural topologies and symmetries

Hydrothermal reactions of divalent transition metal salts with two different-sized tetrazole-yl acylamide ligands, N-(1H-tetrazol-5-yl)acetamide (H-NTAA) and N-(1H-tetrazol-5-yl)propionamide (H-NTPA), led to six crystalline coordination polymers, named Cd(NTAA)2 (1), Zn(NTAA)2·∼H2O (2), Cu(NTAA)2 (3), Mn(NTAA)2 (4), Cd(NTPA)2 (5), Mn(NTPA)2 (6), respectively. The X-ray diffraction analysis revealed that compound 2 is a 1D zigzag chain, compounds 3 and 4 exhibit an interesting 2D 44-sql network, while compounds 1, 5 and 6 possess a 3D non-interpenetrated diamondoid framework. Wherein, compounds 1, 4, 5 and 6 crystallized in an acentric space group with significant second harmonic generation (SHG) efficiencies. The effect of metal ions and that of small aliphatic acyl side-groups in semirigid tetrazole-yl acylamide ligands on the structural topologies and symmetries of generated coordination polymers are discussed.