In an attempt to synthesize the complex [Fe(CN)5(N2)]3- by reaction of Na[Fe(CN)5(NO)]·2H2O with azide followed by treatment with NO[SbCl6], a similar method to that used by Feltham to obtain trans-[RuCl(N2)(das)2]Cl2 from trans-[RuCl(NO)(das)2]Cl2, we found spectroscopic evidence that excess azide reacts with the CN- ligands to generate tetrazolato groups C-coordinated to Fe. Initial results suggest that the obtained compound is sodium azidotris(2H-tetrazolato)(5H-tetrazolato)iron(0). The spectroscopic evidence also indicates that these heterocycles are destroyed by reaction with NO[SbCl6], and the CN- groups are regenerated. Here we present the characterization of these complexes by IR, 13C NMR, conductivity measurements, elemental analysis and magnetic susceptibility.