Heat of Formation of Triazole‐Based Salts: Prediction and Experimental Validation

Abstract

This work contributes to the growing interest in predictions linked with energetic salts. A reliable method to accurately compute the heat of formation of triazole-based salts was investigated. Calculations were based on Born-Haber energy cycles: gas-phase enthalpy of ions and lattice enthalpy were calculated separately. Ten triazole-based salts were synthesized and fully characterized. Their heat of combustion was measured by bomb calorimeter. Gas-phase heat of formation of cations and anions were computed at four different levels of theory: B3LYP 6-31G(d,p), CBS-4M, CBS-QB3, and G4. Ionic volumes were calculated at the B3LYP 6-31G(d,p) level with and without corrections. Lattice enthalpy estimations, based on calculated ionic volumes, were performed with the help of Jenkins and Gutowski methods. Combinations of the obtained results (gas-phase enthalpy of ions and lattice enthalpy) were used in the Born-Haber approach to predict solid phase enthalpy of formation of studied energetic salts. Direct comparison with experimental measurements enabled the identification of the most reliable path for energetic salt standard enthalpy of formation prediction.

Quantum-Chemical Study of Gas-Phase 5/6/5 Tricyclic Tetrazine Derivatives

“…In the fundamental work of Curtiss [12], a thorough analysis of the accuracy of quantum-chemical calculations of thermochemical quantities on the example of 454 structures was performed using the G4 method within the Gaussian software, and it was shown that the average deviation of the calculation results from the experimental values in this case was only 0.8 kcal/mol, which for high-enthalpy substances was less than 1%. Over the past 15 years, many studies [13][14][15] of the approaches to calculate ∆H • f for a wide range of substances of various classes, using high-level calculations, have shown that methods of the Gaussian family, in particular G4, are effective to estimate ∆H • f of high-energy polynitrogen compounds.…”