3,4,5-Triamino-1,2,4-triazole (guanazine, 1) can be readily methylated with methyl iodide yielding methylguanazinium iodide (2). Salts containing the novel methylguanazinium cation with energetic anions were synthesised by metathesis reactions with silver azide (3), silver nitrate (4), silver perchlorate (5), sodium 5,5'-azotetrazolate (6), silver 5-nitrotetrazolate (7) and silver dinitramide (8), yielding a new family of heterocycle-based salts, which were fully characterised by analytical (mass spectrometry and elemental analysis) and spectroscopic methods (IR, Raman and NMR). In addition, the molecular structures of all compounds were confirmed by X-ray analysis, revealing extensive hydrogen-bonding in the solid state and densities between 1.399 (3) and 1.669 g cm(-3) (5). The hydrogen-bonded ring motifs are discussed in the formalism of graph-set analysis for hydrogen-bond patterns and compared to each other. Preliminary sensitivity testing of the crystalline compounds indicate surprisingly low sensitivities to both friction and impact, the highest friction and shock sensitivity being found for the perchlorate (5, 220 N) and the dinitramide (8, 20 J) salts, respectively. In addition, DSC analysis was used to assess the thermal stabilities of the compounds: 3-6 melt above 200 degrees C with concomitant decomposition, whereas 7 and 8 have clearly defined melting points at 162 and 129 degrees C, respectively, and with decomposition occurring about 30 degrees C above the melting point. Lastly all compounds have positive calculated heats of formation between 336 (4) and 4070 kJ kg(-1) (6) and calculated detonation velocities in the range between 8330 (7) and 8922 m s(-1) (6) making them of interest as new highly energetic materials with low sensitivity.

3,4,5-Triamino-1,2,4-triazolium iodide (1) was obtained in good yield and purity and characterized using vibrational (IR, Raman) and multinuclear NMR spectroscopy ( 1 H, 13 C, 15 N), EA, MS, DSC, and X-ray crystallography. The compound was synthesized by two different methods rendering two different polymorphs (α and β) as proved by X-ray measurements, vibrational spectroscopy and DSC. 1-Methyl-3,4,5-triamino-1,2,4-triazolium iod-61 ide (2) was synthesized by reaction of guanazine with methyliodide and fully characterized by the same techniques mentioned above. Both compounds showed to be suitable starting materials for the synthesis of guanazinium salts of energetic interest.Scheme 1 Structures of the title compounds 1 and 2 (1A, 1B ϭ α and β polymorphs, respectively).Scheme 3 15 N and 15 N{ 1 H} NMR spectra (DMSO-d 6 ) of 1 (a) N6: Ϫ321.9 ppm, t, J ϭ 75.7 Hz; N3/N5: Ϫ329.5 ppm, t, J ϭ 88.5 Hz and 2 (b) N6: Ϫ319.8 ppm, t, J ϭ 80.3 Hz; N3: Ϫ321.9 ppm, t, J ϭ 71.4 Hz; N5: Ϫ334.1 ppm, t, J ϭ 72.1 Hz.3,4,5-Triamino-1,2,4-triazolium and 1-Methyl-3,4,5-triamino-1,2,4-triazolium Iodides

1,1,4,4-Tetramethyl-2-tetrazene (TMTZ) is considered as a prospective replacement for toxic hydrazines used in liquid rocket propulsion. The heat of formation of TMTZ was computed and measured, giving values well above those of the hydrazines commonly used in propulsion. This led to a predicted maximum I of 337 s for TMTZ/N O mixtures, which is a value comparable to that of monomethylhydrazine. We found that TMTZ has a vapor pressure well below that of liquid hydrazines, and it is far less toxic. Finally, an improved synthesis is proposed, which is compatible with existing industrial production facilities after minor changes. TMTZ is thus an attractive liquid propellant candidate, with a performance comparable to hydrazines but a lower vapor pressure and toxicity.