Vibrational spectra, DFT chemical quantum calculations and conformation of the hydrazo-bond in 2,2′-hydrazobipyridine with relation to 2,2′-azobipyridine

Synthesis of 2,2′-hydrazobipyridine is described. FT-IR and Raman spectra of this compound have been measured and compared to the spectra of 2,2′-azobipyridine and pyridine. The 6-31G basis set with the B3LYP functional has been used to discuss the structure and vibrational dynamics of the compounds studied. The vibrational properties of the azo- and hydrazo-bonds are correlated with the molecular structures. The characteristic vibrational features observed in the range 3300-2700 cm−1 are assigned to the NH⋯N hydrogen bonds formed in the hydrazobipyridine.