Tetraaquabis[5-(3-pyridyl)tetrazolido-κN⁵]zinc(II) tetrahydrate

Abstract

The title compound, [Zn(C6H4N5)2(H2O)4]·4H2O, was synthesized by the hydro­thermal reaction of Zn(CH3COO)2·2H2O with 3-(2H-tetra­zol-5-yl)pyridine. The ZnII ion is located on an inversion center and is coordinated by two pyridine N atoms from two 5-(3-pyrid­yl)tetra­zolide ligands and four coordinated water mol­ecules in a slightly distorted octa­hedral geometry. The dihedral angle between the pyridine and tetra­zole rings is 9.920 (7)°. In the crystal, mol­ecules are linked into a three-dimensional network by inter­molecular O—H⋯O and O—H⋯N hydrogen bonds involving the tetra­zole group N atoms, the aqua ligands and solvent water mol­ecules.

pH-Controlled Assembly of 3D and 2D Zinc-Based Metal-Organic Frameworks with Tetrazole Ligands

“…15c For pH values slightly below 7.0, we obtained mixed phases of the 3D MOF Zn(3-ptz) 2 and the triclinic crystal Zn(H 2 O) 4 (3-ptz) 2 ·4H 2 O ( ZAC ). 22…”

“…20 The strong Zn–OH coordination bond results in a solvated coordination sphere with lower symmetry than the octahedral coordination sphere of the hexa-aquo Zn 2+ ion, which is the dominant species at lower pH. The 3-ptz ligands thus prefer to coordinate with the zinc ion in directions orthogonal to the Zn–OH bond, minimizing steric effects, a bonding pattern exhibited in both ZAC (22) and 2D MOF (15d) crystals.…”

“…For pH values in the lower range (pH < 5.0), the diffraction peaks are in excellent agreement with the simulated XRD pattern reported for the tetragonal Zn­(3-ptz) 2 structure . For pH values slightly below 7.0, we obtained mixed phases of the 3D MOF Zn­(3-ptz) 2 and the triclinic crystal Zn­(H 2 O) 4 (3-ptz) 2 ·4H 2 O ( ZAC ) …”

“…Alkaline environments strongly favor the assembly of the 2D MOF structure Zn(OH)(3-ptz) , 15d whose rodlike crystal morphology can be manipulated by changing the initial reaction pH within the range 7.5–11.0. The synthesis carried out without initial pH manipulation (pH = 6.4) gives a mixed phase of the 3D MOF Zn(3-ptz) 2 and the zinc-tetra-aqua complex [Zn(3-ptz) 2 (H 2 O) 4 ]·4H 2 O , 22 which can be efficiently separated by high-temperature filtration. Although the solvothermal syntheses of Zn(3-ptz) 2 and Zn(OH)(3-ptz) metal-organic frameworks has been previously reported by varying the reaction time and temperature, 15c,15d we show for the first time that it is possible to obtain these MOFs in high purity by simply varying the mixing pH of the reactants.…”