Synthesis and spectroscopic properties of new bis-tetrazoles

Syntheses of N,N ′-phenyltetrazole podands link with aliphatic chains containing oxygen, nitrogen and sulphur atoms, are described. The complexing properties of these compounds towards metal cations (Fe 2+ , Cu 2+ , Zn 2+ , Co 2+ , Ni 2+ ) were investigated by absorption and infrared spectroscopy. The UV–Vis titrations were performed to estimate the stability constant values of the respective complexes with Cu 2+ ion. Changes in UV–Vis absorption spectra and IR spectra of compound 6 under various concentrations of Cu 2+ ion in methanol suggest formation of very unstable complex. The structure of ligand 2 has been deduced by X-ray crystallography.