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Crystal packings were modeled for salts of substituted formamidines including formamidinium, guanidinium, azidoformamidinium and nitroformamidinium. The enthalpies of formation for substituted formamidines with various anions were calculated.

Nitronium borates of NO2[B(OX)4] type with X = CF3CO and NO2 as ligands were synthesized, and their structures were determined by powder X-ray diffraction. Crystalline NO2[B(ONO2)4] is relatively stable at room temperature and undergoes transformation to B2O3 upon heating. The [B(CF3COO)4]− anion was obtained for the first time and characterized as a structural fragment of a solid compound. The possibility of reversible modification of the complex anion by replacement of the nitrate or trifluoroacetate ligand was demonstrated for the first time by the mutual transformations of NO2[B(ONO2)4] and NO2[B(CF3COO)4].

A series of novel energetic materials comprising of azo-bridged furoxanylazoles enriched with energetic functionalities was designed and synthesized. These high-energy materials were thoroughly characterized by IR and multinuclear NMR (1 H, 13 C, 14 N) spectroscopy, high-resolution mass spectrometry, elemental analysis, and differential scanning calorimetry (DSC). The molecular structures of representative amino and azo oxadiazole assemblies were additionally confirmed by single-crystal X-ray diffraction and X-ray powder diffraction. A comparison of contributions of explosophoric moieties into the density of energetic materials revealed that furoxan and 1,2,4-oxadiazole rings are the densest motifs while the substitution of the azide and amino fragments on the nitro and azo ones leads to an increase of the density. Azo bridged energetic materials have high nitrogen-oxygen contents (68.8-76.9 %) and high thermal stability. The synthesized compounds exhibit good experimental densities (1.62-1.88 g cm-3 ), very high enthalpies of formation (846-1720 kJ mol-1 ), and, as a result, excellent detonation performance (detonation velocities 7.66-9.09 km s-1 and detonation pressures 25.0-37.7 GPa). From the application perspective, the detonation parameters of azo oxadiazole assemblies exceed those of the benchmark explosive RDX, while a combination of high detonation performance and acceptable friction sensitivity of azo(1,2,4-triazolylfuroxan) make it a promising potential alternative to PETN.

A series of tetrahydroimidazo[4,5-e]thiazolo[3,2-b]-1,2,4-triazine-2,7(1H, 6H)-diones were synthesized via the reaction of imidazotriazinethiones and bromoacetic acid followed by condensation with isatins. Amidine skeletal rearrangement of 3,3a,9,9a-tetrahydroimidazo[4,5-e]thiazolo[3,2-b]-1,2,4-triazine-2,7 (1H, 6H)-diones into 1,3a,4,9a-tetrahydroimidazo[4,5-e]thiazolo[2,3-c]-1,2,4-triazine-2,8 (3H, 7H)-diones under KOH treatment has been studied. The influence of substituents at positions 1,3,3a,6,9a of imidazothiazolotriazine on the ability to undergo rearrangement was analyzed based on experimental data and theoretical calculations. Both imidazothiazolo[3,2-b]triazines and their rearrangement products were evaluated for their cytotoxic activity against rhabdomyosarcoma, A549, HCT116 and MCF7 human cancer cell lines by MTT assay. Among the derivatives, 1,3-diethyl-6-[1-(2-propyl)-2-oxoindolin-3-ylidene]-3,3a,9,9a-tetrahydroimidazo [4,5-e]thiazolo[3,2-b]-1,2,4-triazine-2,7(1H, 6H)-dione 4i was found to have the highest antiproliferative activity toward the tested cell lines (4i: $$\hbox {IC}_{50} = 2.20$$ , 2.29, 0.47 and $$3.11\,{\upmu }\hbox {M}$$ , respectively). The $$\hbox {IC}_{50}$$ value of compound 4i against normal human embryonic kidney cells HEK293 was $$19.34\,{\upmu }\hbox {M}$$ , which appeared to be 6–41-fold higher than $$\hbox {IC}_{50}$$ values of 4i against human cancer cells.

The thermodynamic stability of the furoxan ring annullated with 1,2,3,4-tetrazine 1,3-dioxide cycle was studied. Crystal structure prediction based on global energy minimization in the framework of the atom-atom potential functions method was performed for isomeric furoxano-tetrazinedioxides (FuxTDOs): [1,2,5]oxadiazolo[3,4-e][1,2,3,4]tetrazine 1,5,7-trioxide (1) and [1,2,5]oxadiazolo[3,4-e][1,2,3,4]tetrazine 1,4,6-trioxide (2). The Coulomb energy was calculated with advanced point charge models fitted with high accuracy to the molecular electrostatic potentials of these molecules. The pressure and velocity of detonation of compounds 1 and 2 were estimated using the calculated enthalpy of formation and predicted molecular crystal density, which allows us to consider these compounds as high energetic materials.

A series of highly energetic organic salts comprising a tetrazolylfuroxan anion, explosophoric azido or azo functionalities, and nitrogen-rich cations were synthesized by simple, efficient, and scalable chemical routes. These energetic materials were fully characterized by IR and multinuclear NMR (1 H, 13 C, 14 N, 15 N) spectroscopy, elemental analysis, and differential scanning calorimetry (DSC). Additionally, the structure of an energetic salt consisting of an azidotetrazolylfuroxan anion and a 3,6,7-triamino-7H-[1,2,4]triazolo[4,3-b][1,2,4]triazolium cation was confirmed by single-crystal X-ray diffraction. The synthesized compounds exhibit good experimental densities (1.57-1.71 g cm-3 ), very high enthalpies of formation (818-1363 kJ mol-1 ), and, as a result, excellent detonation performance (detonation velocities 7.54-8.26 kms-1 and detonation pressures 23.4-29.3 GPa). Most of the synthesized energetic salts have moderate sensitivity toward impact and friction, which makes them promising candidates for a variety of energetic applications. At the same time, three compounds have impact sensitivity on the primary explosives level (1.5-2.7 J). These results along with high detonation parameters and high nitrogen contents (66.0-70.2 %) indicate that these three compounds may serve as potential environmentally friendly alternatives to lead-based primary explosives.

A novel general approach towards various nitroazoles via tandem process involving dinitrofuroxan cycloreversion followed by [3+2] cycloaddition of generated in situ nitroformonitrile oxide is developed. The reaction is promoted by addition of catalytic amounts of ionic liquids. Plausible mechanisms of the described processes based on quantum chemical calculations are proposed.