Use of 13C1H coupling constants for the investigation of azide—tetrazole tautomerism in aromatic nitrogen heterocycles. Detection of ditetrazolo [1,5‐a: 1′,5′‐c:] pyrimidine

The proton‐coupled 13C NMR and 1H NMR spectra of azidobenzene, tetrazolo[1,5‐a]pyridine, 2‐azidopyrimidine and tetrazolo[1,5‐a]pyrimidine in different solvents have been analysed, and criteria for using the NMR spectral parameters (especially the 13C‐1H coupling constants) for tautomeric structure determination have been elaborated. The efficiency of these criteria has been demonstrated in studies of azide‐‐tetrazole equilibria in 2,4‐ and 4,6‐diazidopyrimidines. The ditetrazolo tautomeric form of 2,4‐diazidopyrimidine has been found in polar solvents.