Crystallographic characterization of the intermediate in the synthesis of tetrazole from nitrile and azide in water

The intermediate [Zn(4-PTZ)2(H2O)4] (4-PTZ=5-(4-pyridyl N-oxide)tetrazolate) (1) in the synthesis of 4-H-PTZ (2) from cycloaddition reaction of 4-cyanopyridine N-oxide with NaN3 in water catalyzed by ZnCl2 was structurally characterized. The catalysis role of Zn2+ in the synthesis of tetrazole stems from the formation of tetrazolate zinc complex 1.