Crystal structure, thermodynamic properties and detonation characterization of bis(5-amino-1,2,4-triazol-3-yl)methane

Abstract

Bis(5-amino-1,2,4-triazol-3-yl)methane (BATZM, C5H8N8) was synthesized and its crystal structure characterized by single-crystal X-ray diffraction; it belongs to the space group Fdd2 (orthorhombic) with Z = 8. The structure of BATZM can be described as a V-shaped molecule with reasonable chemical geometry and no disorder. The specific molar heat capacity (Cp,m ) of BATZM was determined using the continuous Cp mode of a microcalorimeter and theoretical calculations, and the Cp,m value is 211.19 J K−1 mol−1 at 298.15 K. The relative deviations between the theoretical and experimental values of Cp,m , HT – H 298.15K and ST – S 298.15K of BATZM are almost equivalent at each temperature. The detonation velocity (D) and detonation pressure (P) of BATZM were estimated using the nitrogen equivalent equation according to the experimental density; BATZM has a higher detonation velocity (7954.87 ± 3.29 m s−1) and detonation pressure (25.72 ± 0.03 GPa) than TNT.

Crystal Structure, Thermal Behavior and Detonation Characterization of Bis(3‐nitro‐1H‐1,2,4‐triazol‐5‐yl)methane

“…Single crystal analysis shows that BNTZM crystallizes in orthorhombic space group Fdd 2 with Z=8, the above data is the same as BATZM [15]. These indicate that nitrification has no effect on these parameters, of course, the volume has changed, the Δ V between BNTZM and BATZM is 0.0390 nm 3 /molecular, this result is mainly caused by two nitro group.…”

“…D and P can be obtained according to Equations (6) and (7), viz . 7749 m s −1 and 25.9 GPa, respectively, are lower than these of BATZM (7955 m s −1 and 25.7 GPa) [15], these indicate that amino group can improve the detonation characterization. The lower space utilization of BNTZM is the main reason for this result.…”

“…The bond length of C1‐N4 is the longest C−N bond (Table S3), which indicates that the initial decomposition step of BNTZM is the loss of NO 2 . The bond length of C1‐N4 is longer than C1‐N4 of BATZM [15], this also indicates that nitro group leads BNTZM has worse thermal stability than BATZM. Figure 2 illustrates that each BNTZM molecule is cross‐connected with four BNTZM molecules through hydrogen bond of N2‐H2⋅⋅⋅N3 (Table S4) to form a 3D network.…”

Hydrogen-bond-modulated negative linear compressibility in a V-shaped molecular crystal

“…Experimentally, BATZM crystallizes in the orthogonal Fdd 2 space group with lattice parameters of 18.632, 19.933 and 4.3095 Å for a -, b - and c -axis, respectively. 28 The X-ray structure of the V-shaped BATZM molecule with atom labels is shown in Fig. 1a.…”