On the choice of optimal protocol for calculation of 13C and 15N NMR isotropic chemical shifts in nitramine systems

Abstract Calculated nuclear magnetic resonance (NMR) chemical shifts ( 13 C and 15 N) are reported for the RDX conformers and additional nine cyclic and acyclic nitramines. In order to establish a convenient and consistent protocol to be employed for confirming the experimental 13 C and 15 N NMR spectra of nitramine compounds, different combinations of models and basis sets were considered. The most reliable results were obtained at B3LYP/6-311+G(2d,p) level and CSGT model and can be used to calculate 13 C and 15 N NMR chemical shifts with a very high accuracy for nitramine compounds. These results show that the agreement between theoretical and experimental 15 N NMR chemical shieldings of nitramines could be used for the evaluation of the intrinsic relationship between structure and explosive properties.