Investigating the structure-stability relationship in bridging isomers of bistetrazoles

Subtle modifications in the molecular structure of materials can have a profound impact on their properties because of the nature of bonding, strength of inter and intramolecular interactions, and the spatial arrangement of atoms. 5,5'-Bis-1H-tetrazole and 5-(tetrazol-1-yl)-2H-tetrazole are two structural isomers, with C-C and C-N linkages between the two tetrazole rings. These structural isomers exhibit distinct thermal behaviors and significant differences in their decomposition temperatures. To understand the differences in thermal stability, a combined experimental and computational study was performed using thermal analysis, Hirshfeld surface analysis, and 2D fingerprint plot analysis. The activation energy for the decomposition of these compounds was computed using isoconversional kinetic analysis to obtain insights into the stability of these compounds at elevated temperatures. A plausible fragmentation pattern was elucidated using high-resolution mass spectrometry (HRMS) and tandem mass spectrometry (MS/MS) data. Density functional theory (DFT) calculations of both the neutral and anionic forms were performed to understand the transition pathways for the decomposition of these compounds and to validate the fragmentation patterns obtained from mass spectrometry.