242815-93-6Relevant articles and documents
1H, 13C and 15N NMR and IR studies of halogen-substituted tetrazolo[1,5-a]pyridines
Cmoch,Korczak,Stefaniak,Webb
, p. 470 - 478 (2007/10/03)
The tetrazole-azide tautomerization of some halogen-substituted tetrazolo[1,5-a]pyridines was examined by IR spectroscopy at ambient temperature and by 1H, 13C and 15N NMR spectroscopy at various temperatures. The tetrazolopyridines can exhibit equilibrium between the azide and the tetrazole forms. For some of them slow exchange occurs on the NMR time-scale, such that it is possible to estimate equilibrium constants. The position and nature of the substituent in the pyridine ring result in stabilization or destabilization of the tetrazole form and exert a strong influence on the values found for the equilibrium constants. A saturation transfer experiment was carried out for 5-bromotetrazolo[1,5-a]pyridine and the rate constants were estimated. Moreover, based on the van't Hoff equation, the enthalpy ΔHo and entropy ΔSo for the tautomerization were calculated. Ab initio calculated energies and charge distribution are in good agreement with differences observed in the tetrazole-azide equilibrium constants. Copyright
