Structure and Thermal Properties of 2,2'-Azobis(1H-Imidazole-4,5-Dicarbonitrile)-A Promising Starting Material for a Novel Group of Energetic Compounds.

A high-nitrogen compound, 2,2'-azobis(1H-imidazole-4,5-dicarbonitrile) (TCAD), was synthesized from commercially available 2-amino-1H-imidazole-4,5-dicarbonitrile. It was characterized with infrared and nuclear magnetic resonance spectroscopy. Its structure was determined by single crystal X-ray diffraction. The crystal of TCAD tetrahydrate is monoclinic, with space group P21/c with crystal parameters of a = 10.2935(2) Å, b = 7.36760(10) Å, c = 20.1447(4) Å, V = 1500.27(5) Å3, Z = 4, and F(000) = 688. Computational methods were used in order to fully optimize the molecular structure, calculate the electrostatic potential of an isolated molecule, and to compute thermodynamic parameters. TCAD has very high thermal stability with temperature of decomposition at 369 °C. Kinetics of thermal decomposition of this compound were studied and apparent energy of activation as well as the maximum safe temperature of technological process were determined.