Exploring the Explosive Potential: Synthesis and Characterization of Ring-Fused Oxadiazolo[3,4-b]pyrazine 1-Oxide Polymorphs with Balanced Energetic Properties.

A novel fused-ring compound, 5-azido-6-oxo-6,7-dihydro-[1,2,5]oxadiazolo[3,4-b]pyrazine 1-oxide (3a), was synthesized for the first time with simple two-step process and characterized using various spectroscopic techniques such NMR, IR, EA and HRMS. Two polymorphs (α-3a and ß-3a) identified by SCXRD differ in crystal packing and noncovalent interactions, demonstrating high density, substantial heat of formation, and superior detonation properties with reduced mechanical sensitivity compared to TNT, TATB, and close to RDX, suggesting their potential as environmentally friendly high energy density materials.

Bistriazolotriazole-tetramine: commendable energetic moiety and cation.

CONTEXT: Various 7H,7'H-[6,6'-bi[1,2,4]triazolo[4,3-b][1,2,4]triazole]-3,3',7,7'-tetramine (A) based nitrogen-rich energetic salts were designed and their properties explored. All energetic salts possess relatively high nitrogen content (> 48%), positive heats of formation (> 429 kJ/mol) and stability owing to a significant contribution from fused backbone. The cationic component shows a very high heat of formation (2516 kJ/mol); therefore, it is highly suitable for enthalpy enhancement in new energetic salts. The cation was paired with the energetic anions nitrate (NO3-), perchlorate (ClO4-), dinitromethanide (CH(NO2)2-), trinitromethanide (C(NO2)3-), nitroamide (NHNO2-), and dinitroamide (N(NO2)2-) to improve oxygen balance and detonation performance. Designed salts show moderate detonation velocities (7.9-8.7 km/s) and pressures (23.8 - 33.1 GPa). The distribution of frontier molecular orbitals, molecular electrostatic surface potentials, QTAIM topological properties, and noncovalent interactions of designed salts were simulated to understand the electronic structures, charge distribution in molecules, hydrogen bonding, and other nonbond interactions. The predicted safety factor (SF) and impact sensitivity (H50) of designed salts suggest their insensitivity to mechanical stimuli. This work explored the 7H,7'H-[6,6'-bi[1,2,4]triazolo[4,3-b][1,2,4]triazole]-3,3',7,7'-tetramine as a suitable cationic component which could be promising and serve exemplarily in energetic materials. METHODS: The optimization and energy calculations of all the designed compounds were carried out at the B3LYP/6-311 + + G(d,p) and M06-2X/def2-TZVPP levels, utilizing the Gaussian software package. The molecular surface electrostatic potential, quantum theory of atoms in molecules (QTAIM), reduced density gradient (RDG), and noncovalent interaction (NCI) analysis were performed by employing Multiwfn software. The EXPLO5 (v 7.01) thermochemical code and PILEM web application were used to predict the detonation properties.