Theoretical design of bistetrazole diolate derivatives as novel non-nitro energetic salts with low sensitivity

Abstract

Most conventional high energetic molecules contain nitro group that endows them with high sensitivities. To overcome this disadvantage, 11 novel bistetrazole-diolated anions were designed by inserting different bridges into the dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50) framework. Forty-two energetic salts were formulated from the bistetrazole-diolated anions and ammonium-based cations, which were paired according to their thermal stability. Their crystal densities, heats of formation (HOFs), energetic properties, and impact sensitivity were predicted using density functional theory (DFT) and volume-based thermodynamics calculations (VBT). It is found that the introduction of the tetrazole ring to the bridge of bistetrazole diolate is the most efficient to get high density, while the introduction of the tetrazine ring as a bridge is a good choice in order to obtain excellent HOFs. However, azo group is more helpful to obtain good detonation properties due to its better oxygen balance, and its corresponding dihydroxylammonium salt exhibits better detonation performance (D = 9.41 km s−1 and P = 41.27 GPa) than TKX-50 (A3, D = 9.25 km s−1 and P = 39.53 GPa). Therein, 18 energetic salts are endowed with better detonation properties and much lower sensitivity than the commonly used 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX). The construction of the non-nitro energetic anions like bistetrazole diolate and oxygenated cation like hydroxylammonium is a potential efficient way for screening out the high energy density materials (HEDMs) with low sensitivity.