Tetraaquabis[5-(4-pyridyl N-oxide)tetrazolato-kappaN(2)]cadmium: the intermediate in the synthesis of a tetrazole from a nitrile and an azide.

The intermediate [Cd(4-PTZ)(2)(H(2)O)(4)] [4-PTZ is 5-(4-pyridyl N-oxide)tetrazolate, C(6)H(4)N(5)O], (I), in the synthesis of 4-HPTZ, (II), from the cycloaddition reaction of 4-cyanopyridine N-oxide with NaN(3) in water using CdCl(2) as catalyst, was structurally characterized. The unique Cd atom lies on a twofold axis and the coordination geometry of the Cd atom is that of a slightly distorted octahedron, involving four water molecules and two tetrazolate ligands. The catalytic role of the Cd(2+) ion in the tetrazole generation reaction stems from the formation of (I). In acidic solution, (I) can be disassociated and the free ligand, (II), can be released.