Quantum-chemical studies of infrared spectra of ¹⁵N labeled diazene isomers

The geometry of trans-HN=NH, cis-HN=NH and N=NH₂ containing no, one or two ¹⁵N labeled atoms was optimized. The corresponding infrared vibrations were evaluated using a linear scaling factor. For each of these compounds at least one vibration can be found, which enables to distinguish between heteroisotopic ¹⁴N=¹⁵N and homoisotopic ¹⁴N=¹⁴N or ¹⁵N=¹⁵N species. Independent of the ¹⁵N labeling, only trans-conformation should be found in the reaction mixture under equilibrium conditions.