Understanding the Stability of Highly Nitrated Sensitive Pyrazole Isomers.

Two energetic isomers of chemically unstable 3,5-bis(dinitromethyl)-4-nitro-1 H -pyrazole ( 2 ), namely, 4-methyl-3,5-dinitro-1-(trinitromethyl)-1 H -pyrazole ( 4 ) and 5-methyl-3,4-dinitro-1-(trinitromethyl)-1 H -pyrazole ( 6 ), each containing five nitro groups and having the same chemical composition, exhibit major differences in their physiochemical properties. These include density, enthalpy of formation, temperature of decomposition, and sensitivity to impact and friction. Notably, both isomer 4 and isomer 6 demonstrate superior thermal stability compared to isomer 2 , making them promising candidates as safer energetic materials.