Predicting heats of explosion of nitroaromatic compounds through NBO charges and 15 N NMR chemical shifts of nitro groups

Abstract

This work presents a new quantitative model to predict the heat of explosion of nitroaromatic compounds using the natural bond orbital (NBO) charge and 15N NMR chemical shifts of the nitro groups ( 15N Nitro) as structural parameters. The values of the heat of explosion predicted for 21 nitroaromatic compounds using the model described here were compared with experimental data. The prediction ability of the model was assessed by the leave-one-out cross-validation method. The cross-validation results show that the model is significant and stable and that the predicted accuracy is within 0.146 MJ kg -1, with an overall root mean squared error of prediction (RMSEP) below 0.183 MJ kg -1. Strong correlations were observed between the heat of explosion and the charges (R 2 = 0.9533) and 15N NMR chemical shifts (R 2 = 0.9531) of the studied compounds. In addition, the dependence of the heat of explosion on the presence of activating or deactivating groups of nitroaromatic explosives was analyzed. All calculations, including optimizations, NBO charges, and 15N Nitro NMR chemical shifts analyses, were performed using density functional theory (DFT) and a 6-311+G(2d,p) basis set. Based on these results, this practical quantitative model can be used as a tool in the design and development of highly energetic materials (HEM) based on nitroaromatic compounds. Copyright © 2012 Ricardo Infante-Castillo and Samuel P. Hernández-Rivera.