Density Functional Theory and Experimental Studies of the Molecular, Vibrational, and Crystal Structure of...

Density function theory (DFT) and experimental characterization of energetic materials play important roles in understanding molecular structure-property relations and validating models for their predictive capabilities. Here, we report our modeling and experimental results on the molecular, vibrational, and crystal structure of energetic bis-oxadiazole-bis-methylene dinitrate (BODN) obtained by molecular DFT (M-DFT) at the B3LYP- 6-31G** level, crystal DFT (C-DFT) using the Perdew-Burke-Ernzerhof functional optimized with norm-conserving pseudopotentials, X-ray diffractometry, infrared and Raman spectroscopy, and thermogravimetric analysis. Both models predict well the experimental bond lengths, bond angles, and torsion angles of BODN. The C-DFT lattice constant values are in excellent agreement with those determined experimentally, with unit cell length and angle values differing by less than 1.2 and 0.7%, respectively. BODN presents van der Waals O···H and O···C bifurcated intramolecular contacts and short N···H and O···O intermolecular contacts. Overall, the predicted vibrational energies of both models are in line with experiment. M-DFT thermodynamic calculations predict well the experimentally derived lattice energy (-131 kJ/mol) and the M-DFT electrostatic potential calculations reveal a low sensitivity to impact. In addition, C-DFT band gap calculations predict a value of 3.80 eV for BODN, resulting predominantly from the ring O and N atoms, suggesting it is insensitive to impact. These results are compared and contrasted with those obtained in this study or reported previously for 3,3-bis-isoxazole-5,5'-bis-methylene dinitrate (BIDN).