Infrared spectra of acid azides, carbamyl azides and other azido derivatives: anomalous splittings of the N₃ stretching bands

Abstract

The infrared spectra of organic acid azides, carbamyl azides, vinyl azides and alphaazido ethers, thioethers and amines have been investigated in detail. The acid azides and the carbamyl azides show the characteristic N₃ and carbonyl absorptions and have been assigned the acyclic azide structure. The amide bands of carbamyl azides have also been assigned. The asymmetric and symmetric stretching frequencies of the azido group are generally found in the regions 2162-2095 and 1258-1206 cm⁻¹, respectively. The anomalous splittings of the N₃ stretching bands have been explained in terms of Fermi interaction with combination tones involving the N₃ symmetric and C-N stretching vibrations and other low lying frequencies.