Tandem deprotonation/azide-tetrazole tautomerization of 4,6-diazido-N-nitro-1,3,5-triazin-2-amine in dimethylsulfoxide solutions: a theoretical studyElectronic supplementary information (ESI) available: The experimental 15N NMR spectrum of diazide 1 and computational details including Cartesian coordinates, M06-2X/SMD energies, gas-phase thermal corrections, relative free energies in the solution and GIAO-DFT calculated chemical shifts. See DOI: 10.1039/c5cp02096d

4,6-Diazido- N -nitro-1,3,5-triazin-2-amine ( 2 ) is a new promising high-energy organic compound that isomerizes in dimethylsulfoxide (DMSO) solutions to form unknown products with interesting 13 C and 15 N NMR spectroscopic characteristics. To identify these products, the relative energies and the 13 C and 15 N chemical shifts were calculated for various prototropic and valence isomers of 2 . It was found that this diazide in DMSO solutions exists in equilibrium with the deprotonated form of 5-azido- N -nitrotetrazolo[1,5- a ][1,3,5]triazin-7-amine ( 8 ). The anion 8 is also observed in DMSO solutions of energetic salts derived from 2 and guanidines or 4 H -1,2,4-triazol-4-amines. The tandem transformations of 2 in DMSO solutions found may be of interest from both theoretical and practical points of view, for instance, in the synthesis of new energetic materials, using the reactions of anion 8 with various electrophilic agents. 4,6-Diazido- N -nitro-1,3,5-triazin-2-amine in DMSO- d 6 undergoes tandem deprotonation/azide-tetrazole tautomerization to yield the anionic form of 5-azido- N -nitrotetrazolo[1,5- a ][1,3,5]triazin-7-amine.