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Thermal stability of the N₁₀ compound with extended nitrogen chain

Qi, Cai, Zhang, Ru-Bo, Pang, Si-Ping
RSC advances 2013 v.3 no.39 pp. 17741-17748
azoles, chemical structure, heat production, models, nitrogen, nitrogen content, potential energy, thermal degradation, thermal stability
1,1′-Azobis(tetrazole) (N₁₀) as a potential eco-friendly material, has the highest nitrogen content among the azo-stabilized poly-nitrogen compounds. The detailed potential energy surface of N₁₀ was thoroughly investigated using M06-2X, MP2 and CCSD(T) calculations, and the main decomposition pathways were calculated by canonical transition state theory modeling. Amongst all the channels studied, ring opening of the N₁₀ compound, followed by N₂ elimination to form the linear molecule Im8 is predicted to be the primary decomposition channel. The linear species formed (Im8) is characterized by a successive four-nitrogen atom chain stabilized by two terminal HNC groups. Its thorough decomposition reaction is strongly exothermic with a barrier height of 67.5 kcal mol⁻¹. TST calculations were performed to probe the influence of temperature on the rate coefficients at 1 atm. Based on the thermal decomposition mechanism of N₁₀, the novel species N₁₂ and N₁₄ were explored. These longer nitrogen chain compounds having higher nitrogen content than N₁₀ are strongly expected to improve performance of high energy density materials. It is found that the predicted structures could exist at room temperature by comparison of their energetic barriers with the corresponding primary N₂-elimination reaction of N₁₀.