Multisubstituted Imidazolo[4,5-d]pyridazine Fused Ring System Resulting from Nitroamine–Nitroimine Tautomerism

Abstract

A series of multisubstituted imidazolo [4,5-d]pyridazine fused ring compounds was synthesized in which nitroamine−nitroimine tautomerism is exhibited. The electrostatic potential indicates that the nitroimino group has the lowest negative value, second only to the nitro group, culminating in the nitroamino area, which has the highest positive value. In addition, a strong hydrogen bond system which arises from the newly formed nitroimino tautomer suggests that the nitroimino is more stable than its nitroamino analogue.

Nitroimino as an energetic group in designing energetic materials for practical use, a tautomerism from nitroamino

“…This series of compounds 23-26 with novel dicyclic backbones has been reported by Shreeve's group in recent years, which can be obtained by a very concise synthesis route. 13,14,47,48 The construction of these fused-ring skeletons was by reacting hydrazine hydrate with dinitrile (Scheme 10), which also resulted in the introduction of two amino groups. Then the nal compound was obtained by a nitration reaction.…”

Facile synthesis of thermally stable tetrazolo[1,5-b][1,2,4]triazine substituted energetic materials: synthesis and characterization

“…[1][2][3] Fused heterocycles constitute a large variety of structural scaffolds and recent accomplishments of several research groups globally confirmed that the presence of fused backbones in energetic materials usually enhances the energy and nitrogen content, detonation performance, insensitivity and thermal stability, which enhances their practical applicability. [4][5][6][7][8] Nitrogen-rich fused heterocycles have more extensive N-C, N-N and NvN high-energy bonds in the structure than single-ring heterocycles, which provide high energy content to these compounds. A few combinations of strained fused catenated heterocyclic compounds have also been synthesized and their energetic properties were examined, which showed good thermal stability and insensitivity towards external stimuli such as impact and friction.…”

Synthesis and Properties of 1,2,4-Triazol-3-one-Based Energetic Compounds

“…To match with the actual applications, these substances are defined as primary explosives and secondary explosives based on their sensitivities toward external stimuli and detonation abilities. Among the secondary explosives, heat-resistant explosives have drawn extensive attention for their promising applications in aerospace surveys and deep drilling. − Figure a lists the structures and properties of traditional heat-resistant explosives such as 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), hexanitrostilbene (HNS), and 5,5′-bis­(2,4,6-trinitrophenyl)-2,2′-bi­(1,3,4-oxadiazole) (TKX-55). − All these compounds have high thermal stabilities and decompose above 300 °C. However, the detonation velocities of these compounds are not so satisfying (about 8000 m s –1 ), mainly due to their low heats of formation (Δ H f = −139.7; 78.2; 197.6 kJ mol –1 ).…”