Enthalpy of Formation of the Nitrogen-Rich Salt Guanidinium 5,5′-Azotetrazolate (GZT) and a Simple Approach for Estimating the Enthalpy of Formation of Energetic C, H, N, O Salts
Author:
Silva Ana L. R.1ORCID, León Gastón P.1ORCID, Ribeiro da Silva Maria D. M. C.1ORCID, Klapötke Thomas M.2, Reinhardt Jelena2
Affiliation:
1. Centro de Investigação em Química (CIQUP), Institute of Molecular Sciences (IMS), Department of Chemistry and Biochemistry, Faculty of Sciences of University of Porto (FCUP), Rua do Campo Alegre, P-4169-007 Porto, Portugal 2. Department of Chemistry, Inorganic Chemistry, Small Molecule and Energetic Materials Research, LMU Munich, Butenandtstraße 5-13, 81377 Munich, Germany
Abstract
The discrepancy between the calculated (CBS-4M/Jenkins) and experimentally determined enthalpies of formation recently reported for the 2:1 salt TKX-50 raised the important question of whether the enthalpies of formation of other 2:1 C, H, N, O salts calculated using the CBS-4M/Jenkins method are reliable values. The standard (p° = 0.1 MPa) enthalpy of formation of crystalline guanidinium 5,5′-azotetrazolate (GZT) (453.6 ± 3.2 kJ/mol) was determined experimentally using static-bomb combustion calorimetry and was found to be in good agreement with the literature’s values. However, using the CBS-4M/Jenkins method, the calculated enthalpy of formation of GZT was again in poor agreement with the experimentally determined value. The method we used recently to calculate the enthalpy of formation of TKX-50, based on the calculation of the heat of formation of the salt and of the corresponding neutral adduct, was then applied to GZT and provided excellent agreement with the experimentally determined value. Finally, in order to validate the findings, this method was also applied to predict the enthalpy of formation of a range of 1:1 and 2:1 salts (M+X− and (M+)2X2− salts, respectively), and the values obtained were comparable to experimentally determined values. The agreement using this approach was generally very good for both 1:1 and 2:1 salts; therefore, this approach provides a simple and reliable method which can be applied to calculate the enthalpy of formation of energetic C, H, N, O salts with much greater accuracy than the current, commonly used method.
Funder
Fundacão para a Ciência e Tecnologia Office of Naval Research Strategic Environmental Research and Development Program
Subject
Building and Construction
Reference48 articles.
1. Klapotke, T.M. (2022). Chemistry of High-Energy Materials, De Gruyter Textbook. [6th ed.]. 2. Frisch, M.J., Trucks, G.W., Schlegel, H.B., Scuseria, G.E., Robb, M.A., Cheeseman, J.R., Scalmani, G., Barone, V., Petersson, G.A., and Nakatsuji, H. (2016). Gaussian 16, Revision C.01, Gaussian, Inc. 3. Thermodynamic properties of 2-mercapto-, 2,5-dimethyl- and 2-mercapto-5-methyl-1,3,4-thiadiazole;Silva;J. Chem. Thermodyn.,2022 4. Silva, A.L.R., Costa, V.M.S., and Ribeiro da Silva, M.D.M.C. (2022). Experimental and Theoretical Investigation on the Thermochemistry of 3-Methyl-2-benzoxazolinone and 6-Nitro-2-benzoxazolinone. Molecules, 27. 5. Effects of the functional groups amino and nitro on the reactivity of benzoxazoles and comparison with homologous benzothiazoles;Silva;J. Phys. Org. Chem.,2020
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