Temperature Tuned Synthesis of Zinc <i>N</i>,<i>N</i>-bis-(1(2)H-tetrazol-5-yl)-amine Complexes: From Zn₃O Cluster-Based 3-Connected 6³-<i>hcb</i> and (3,6)-Connected (4³)₂(4⁶)-<i>kgd</i> Layers to Zn₅(OH)₄ Chain-Based 3D Open Framework

Hydrothermal in situ [2 + 3] cycloaddition reaction of dicyanamide and azide in the presence of Zn(II) ions at 120, 150, and 180 °C generated [Zn4O(Hbta)3(H2O)6] 1, [Zn7(OH)2(Hbta)6(H2O)6] 2, and [Zn5(OH)4(bta)2]·2H2O 3 (H3bta = N,N-bis-(1(2)H-tetrazol-5-yl)-amine), respectively. 1crystallizes in hexagonal space group P6̅2c and shows a layered structure with 3-connected 63-hcb topology in which Zn3O clusters and unsaturated three-coordinate Zn(II) ions function as 3-connected nodes; 2crystallizes in trigonal space group P3̅c1 and also shows a layered structure with (3,6)-connected (43)2(46)-kgd topology in which Zn3O clusters and six-coordinated Zn(II) sites function as 3-connected nodes as 6-connected nodes, respectively; 3 is a 3D organic−inorganic hybrid open framework constructed by Zn5(OH)4 chains. The triply deprotonated bta3− anion is first observed in 3, and rare three-coordinate Zn(II) ions are revealed in 1. Analysis of relationship between structure and synthesis condition reveals that 1 is a metastable kinetic phase whose structure is closely related to that of 2. Both 1 and 2 are constructed by Zn3O(Hbta)3 units and discrete Zn ions. The coordination mode of doubly deprotonated Hbta in 1 and 2 are also same. This study reveals that a higher reaction temperature is helpful to remove amine-hydrogen of H3bta to form triply deprotonated bta anion. The emergence of triply deprotonated bta species may explain why structure of 3 is significantly different from those of 1 and 2. Compounds 1−3 show strong blue-green emission, assigned as ligand-centered π→π* excitation.