Composition and structure of crystals of unknown origin, crystallizing spontaneously from ethylenediamine on standing, has
been determined by elemental analysis, FTIR, 1H and 13C NMR spectroscopy and X-ray diffraction. The crystal with molecular formula C6H14N4 has been found to be a highly symmetric
saturated imino compound with double-ring structure, and unambiguously identified as trans-1,4,5,8-tetraazodecalin by 1H NMR and powder X-ray diffraction based on both its specific AA'BB' spin coupling system and simulated XRD pattern calculated
from available data of previous single crystal structure determination, respectively. Simultaneous TG/DTA measurement shows
one-step degradation of this compound. The volatile decomposition products have been followed by both TG/DTA-MS and TG-FTIR.
Group of the largest fragments (m/z=80, 81 and 82) observed by TG/DTA-MS corresponds to an aromatic 1,4-diazine (pyrazine). In the EGA-FTIR spectrum of released
gaseous species measured at the highest evolution rate by TG-FTIR, ethylenediamine can be identified as another decomposition