New energetic polynitrotetrazoles.

This combined experimental, theoretical and comparative study details the syntheses and chemical characterisation of two new energetic polynitromethyl tetrazole derivatives, namely, 2-(2-nitro-2-azapropyl)-5-(trinitromethyl)-2 H-tetrazole and its fluorine-containing analogue 2-(2-nitro-2-azapropyl)-5-(fluorodinitromethyl)-2 H-tetrazole. Their crystal structures and energetic behaviour are compared to those of their starting materials, the ammonium salts of the corresponding 5-(polynitromethyl)-2 H-tetrazoles. Additionally, the crystal structures of two further related polynitrotetrazoles are presented.

Synthesis, characterisation and crystal structures of two bi-oxadiazole derivatives featuring the trifluoromethyl group.

The synthesis, characterisation, and crystal structure determination of the closely related compounds 3,3'-bi-(5-trifluoromethyl-1,2,4-oxadiazole) and 5,5'-bi-(2-trifluoromethyl-1,3,4-oxadiazole) are reported. These two compounds are known for their bioactivity; however, in this study they serve as model compounds to evaluate the suitability of the heterocyclic oxadiazole ring system for energetic materials when the fluorine atoms in the exocyclic CF3 groups are substituted successively by nitro groups. Quantum chemical calculations for the bi-1,3,4-oxadiazole derivatives with difluoronitromethyl, fluorodinitromethyl, and trinitromethyl groups have been carried out and predict promising energetic performances for both explosive and propulsive applications.

3,3'-Bi(1,2,4-oxadiazoles) featuring the fluorodinitromethyl and trinitromethyl groups.

Here we report on the preparation of two hydrogen atom free 3,3'-bi(1,2,4-oxadiazole) derivatives. 5,5'-Bis(fluorodinitromethyl)-3,3'-bi(1,2,4-oxadiazole) was synthesised by fluorination of diammonium 5,5'-bis(dinitromethanide)-3,3'-bi(1,2,4-oxadiazole). For our previously reported analogue 5,5'-bis(trinitromethyl)-3,3'-bi(1,2,4-oxadiazole), a new synthetic route starting from new 3,3'-bi(1,2,4-oxadiazolyl)-5,5'-diacetic acid was developed. In this course also hitherto unknown 5,5'-dimethyl-3,3'-bi(1,2,4-oxadiazole) was isolated. The compounds were characterised by multinuclear NMR spectroscopy, IR and Raman spectroscopy, elemental analysis as well as mass spectrometry. X-ray diffraction studies were performed and the crystal structures for the 5,5'-dimethyl and 5,5'-(fluorodinitromethyl) derivatives are reported. The energetic 5,5'-(fluorodinitromethyl) and 5,5'-(trinitromethyl) compounds do not contain any hydrogen atoms and show remarkable high densities. Furthermore, the thermal stabilities and sensitivities were determined by differential scanning calorimetry (DSC) and standardised impact and friction tests. The heats of formation were calculated by the atomisation method based on CBS-4M enthalpies. With these values and the room-temperature X-ray densities, several detonation and propulsion parameters, such as the detonation velocity and pressure as well as the specific impulse of mixtures with aluminium, were computed using the EXPLO5 code.