Energetic hydrazine-based salts with nitrogen-rich and oxidizing anions.

1,1,1-Trimethylhydrazinium iodide ([(CH(3))(3)N-NH(2)]I, 1) was reacted with a silver salt to form the corresponding nitrate ([(CH(3))(3)N-NH(2)][NO(3)], 2), perchlorate ([(CH(3))(3)N-NH(2)][ClO(4)], 3), azide ([(CH(3))(3)N-NH(2)][N(3)], 4), 5-amino-1H-tetrazolate ([(CH(3))(3)N-NH(2)][H(2)N-CN(4)], 5), and sulfate ([(CH(3))(3)N-NH(2)](2)[SO(4)]·2H(2)O, 6·2H(2)O) salts. The metathesis reaction of compound 6·2H(2)O with barium salts led to the formation of the corresponding picrate ([(CH(3))(3)N-NH(2)][(NO(2))(3)Ph-O], 7), dinitramide ([(CH(3))(3)N-NH(2)][N(NO(2))(2)], 8), 5-nitrotetrazolate ([(CH(3))(3)N-NH(2)][O(2)N-CN(4)], 9), and nitroformiate ([(CH(3))(3)N-NH(2)][C(NO(2))(3)], 10) salts. Compounds 1-10 were characterized by elemental analysis, mass spectrometry, infrared/Raman spectroscopy, and multinuclear NMR spectroscopy ((1)H, (13)C, and (15)N). Additionally, compounds 1, 6, and 7 were also characterized by low-temperature X-ray diffraction techniques (XRD). Ba(NH(4))(NT)(3) (NT=5-nitrotetrazole anion) was accidentally obtained during the synthesis of the 5-nitrotetrazole salt 9 and was also characterized by low-temperature XRD. Furthermore, the structure of the [(CH(3))(3)N-NH(2)](+) cation was optimized using the B3LYP method and used to calculate its vibrational frequencies, NBO charges, and electronic energy. Differential scanning calorimetry (DSC) was used to assess the thermal stabilities of salts 2-5 and 7-10, and the sensitivities of the materials towards classical stimuli were estimated by submitting the compounds to standard (BAM) tests. Lastly, we computed the performance parameters (detonation pressures/velocities and specific impulses) and the decomposition gases of compounds 2-5 and 7-10 and those of their oxygen-balanced mixtures with an oxidizer.

Metal salts of the 4,5-dicyano-2H-1,2,3-triazole anion ([C4N5]-).

Diaminomaleodinitrile was reacted at low temperatures with in situ generated nitrous acid to form 4,5-dicyano-2H-1,2,3-triazole (1) in yields above 90%. Crystalline 1 was then reacted with one equivalent of a suitable alkali or alkaline earth metal base (typically a hydroxide or a carbonate) in a polar solvent to form the corresponding alkali and alkaline earth metal salts of 4,5-dicyano-2H-1,2,3-triazole (compounds 2-9). The thermal stability of the metal salts 2-9 was assessed by differential scanning calorimetry, which showed excellent thermal stabilities up to above 350 °C. Due to the energetic character of triazole-based salts, initial safety testing was used to assess the sensitivity of compounds 2-9 towards impact, friction, electrostatic discharge and fast heating. These results revealed very low sensitivities towards all four stimuli. Additionally, compounds 2-9 were characterized by mass spectrometry, elemental analysis, infrared and Raman spectroscopy and ((1)H, (13)C and (14)N) NMR spectroscopy. We also determined the solid state structure of the 4,5-dicyano-2H-1,2,3-triazole anion of one of the alkali metal salts (4: Monoclinic, P2(1)/c, a = 9.389(1) Å, b = 10.603(1) Å, c = 6.924(1) Å, ß = 102.75(1)° and V = 1036.58(3) Å(3)) and one of the alkaline earth metal salts (6: Monoclinic, P2(1)/c, a = 9.243(1) Å, b = 15.828(2) Å, c = 6.463(1) Å, ß = 90.23(1)° and V = 945.5(2) Å(3)). Furthermore, we noted the hydrolysis of one of the cyano groups of the 4,5-dicyano-2H-1,2,3-triazole anion in the strontium salt 8 to form the 5-cyano-2H-1,2,3-triazole-4-carboxylic acid derivative 8b, as confirmed by X-ray studies (8b: Monoclinic, P2(1)/n, a = 6.950(1) Å, b = 17.769(1) Å, c = 13.858(1) Å, ß = 92.98(1)° and V = 1709.1(1) Å(3)). Lastly, we computed the NBO and Mülliken charges for the anion of compounds 2-9 and those of the anion of compound 8b.

Alkali and transition metal (Ag, Cu) salts of bridged 5-nitrotetrazole derivatives for energetic applications.

A family of energetic salts based on the novel 5-(5-nitrotetrazole-2-ylmethyl)-tetrazolate anion (NTTz(-)) with alkali metals (Li(+), Na(+), K(+), Rb(+) and Cs(+)) were synthesized by the reaction of the free acid 5-(5-nitrotetrazole-2-ylmethyl)-tetrazole with a suitable alkali metal base (bicarbonate or carbonate) in alcohol or water. The sodium salt () was, in turn, used to form salts containing the NTTz(-) anion and Ag(+) () or Cu(2+) (, and ) cations. The new compounds were characterized by IR, Raman and NMR spectroscopy, mass spectroscopy, elemental analysis and differential scanning calorimetry (DSC). In addition, the solid-state structure of the NTTz(-) anion was determined by diffraction methods using X-ray analysis. We also assessed the energetic properties of the compounds using standardized (BAM) tests. Interestingly, the silver and copper salts are easily and safely initiated by the laser beam generated by a Raman machine and some of the compounds reported here have promising properties for applications as a new class of nitrogen-rich, more environmentally-friendly energetic materials.

Safe 5-nitrotetrazolate anion transfer reagents.

Silver 5-nitrotetrazolate (1) and copper(ii) 5-nitrotetrazolate 5-nitrotetrazole dihydrate (2) are useful reagents for the synthesis of 5-nitrotetrazole (NT) salts. Both compounds were synthesized and characterized by vibrational spectroscopy (IR and Raman) and differential scanning calorimetry (DSC). In addition, their sensitivity towards friction, shock and electrostatic discharge was tested by standard BAM methods. The extremely high sensitivity of both materials makes the transfer of the NT(-) anion using and hazardous and not suitable for up-scaling. In order to diminish the hazards involved with the transfer of the energetic anion and to render the synthesis of NT salts suitable for an industrial scale the two compounds were stabilized by coordination with a chelating ligand and silver(ethylendiamine) 5-nitrotetrazolate and bis(ethylendiamine)copper(ii) 5-nitrotetrazolate were synthesized in high yields. Both the stabilized NT(-) anion transfer reagents were characterized by analytical and spectroscopic methods. In addition, the crystal structure of the ethylendiamine copper complex was determined: orthorombic, Pbca; a = 7.5200(1), b = 14.0124(2), c = 14.7740(2) A; V = 1556.78(4) A(3). Furthermore, we synthesized triaminocopper(ii) 5-nitrotetrazolate, which has potential as a more environmentally-friendly primary explosive. Lastly, the synthetic potential of the ethylediamine adducts and to form energetic salts of NT was investigated.

Alkali metal 5-nitrotetrazolate salts: prospective replacements for service lead(II) azide in explosive initiators.

A family of sensitive energetic salts of the 5-nitrotetrazolate anion with alkali metal cations (Li+, Na+, K+, Rb+ and Cs+) were synthesized either by the digestion of an acid copper salt of 5-nitrotetrazole with a suitable metal hydroxide, or alternatively by reaction of ammonium 5-nitrotetrazolate with a suitable metal base (MOH, MHCO3 or M2CO3) in aqueous or alcoholic solution. All the compounds were characterized by analytical methods (elemental analysis and mass spectrometry) and spectroscopic methods (NMR and vibrational spectroscopy). The lighter metal salts and , incorporate three and two crystal water molecules in the structure, respectively, whereas the heavier alkali metal derivatives form anhydrous species, and thus showed enhanced sensitivity to friction and shock. In addition, the crystal structure of each of the new materials was determined by X-ray diffraction techniques ( and : monoclinic, P2(1)/c; : triclinic, P1; : monoclinic, Cc and : monoclinic, C2/c). The thermal stability of compounds was assessed by differential scanning calorimetry (DSC) measurements showing significant thermal stability. Lastly, the energies of combustion of and were measured experimentally using oxygen bomb calorimetry (, -1340(15) cal g(-1) and , -1200(20) cal g(-1)) and was used to calculate their standard molar heats of formation (, -610(55) kJ mol(-1) and , -360(65) kJ mol(-1)).

1,2,4-triazolium-cation-based energetic salts.

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.

Salts of methylated 5-aminotetrazoles with energetic anions.

1-methyl-5-aminotetrazole (4, MAT) can easily be protonated by strong acids, yielding known but largely uninvestigated 1-methyl-5-aminotetrazolium nitrate (4a) and perchlorate (4b). Methylation, rather than protonation, of 4 with iodomethane followed by the exchange of the iodide (5a) for nitrate (5b), perchlorate (5c), azide (5d), and dinitramide (5e) yields a new family of energetic methylated aminotetrazole salts. In all cases, stable salts were obtained and fully characterized by vibrational (IR, Raman) spectroscopy, multinuclear NMR spectroscopy, mass spectrometry, elemental analysis, and X-ray structure determination. Compounds 4a, 4b, and 5c crystallize in the monoclinic space group P2(1)/n, whereas compounds 5b and 5e crystallize in the orthorhombic space group P2(1)2(1)2(1) and 5d in the orthorhombic Fddd. Initial safety testing (impact, friction, and electrostatic sensitivity) and thermal stability measurements (DSC) were also carried out. The MAT salts all exhibit good thermal stabilities (decomposition above 150 degrees C). The constant volume energies of combustion (DeltacU) of 4a, 5b, 5d, and 5e were determined to be -2510(10) cal/g, -3190(30) cal/g, -4500(100) cal/g, and -2570(70) cal/g, respectively, experimentally using oxygen bomb calorimetry. From the experimentally determined density, chemical composition and energies of formation (back calculated from the heats of combustion), the detonation pressures and velocities of 4a (8100 m/s, 25.6 GPa), 5b (7500 m/s, 20.2 GPa), 5d (8200 m/s, 21.7 GPa), and 5e (7500 m/s, 21.2 GPa) were predicted using the EXPLO5 code.