2,2′-Azobis(1,5′-bitetrazole) with a N10 Chain and 1,5′-Bitetrazolate‑2N‑oxides: Construction of Highly Energetic Nitrogen-Rich Materials Based on C–N-Linked Tetrazoles

A series of high-nitrogen compounds, including a unique molecule 2,2′-azobis(1,5′-bitetrazole) with a branched N10 chain and 1,5′-bitetrazolate-2N-oxides, were synthesized successfully based on C–N-linked 1,5′-bistetrazoles using azo coupling of N-amine bonds and N-oxide introduction strategies. All compounds were characterized by NMR spectroscopy, IR spectroscopy, elemental analysis, and differential scanning calorimetry, in which the structures of five compounds were further determined by single-crystal X-ray diffraction analysis (2, T-N10B, 3a, 3b, and THX). The nitrogen contents of these five compounds range from 63.62 (THX) to 83.43% (T-N10B), which are much higher than that of CL-20 (38.34%). The heat of formation for the prepared compounds was calculated by using the Gaussian 09 program, with T-N10B having the highest value of 5.13 kJ g–1, about 6 times higher than that of CL-20 (0.83 kJ g–1). The calculated detonation performances by EXPLO5 v6.05.04 show that THX has excellent detonation performance (D = 9581 m s–1, P = 35.93 GPa) and a remarkable specific impulse (Isp = 284.9 s).