The Structure and Chemical Bond of FOX-7: The AIM Analysis and Vibrational Normal Modes

FOX-7 (1,1-diamino-2,2-dinitroethylene) recently is expected as a relatively new energetic material with high-performance and low sensitivity. The RHF and MP2 levels and DFT method with B3LYP functional with aug-cc-pVDZ basis set have been used for obtaining equilibrium geometry and Rho function (electron density distribution). By the aid of fundamental physical theorems implemented in the Quantum Theory of Atoms In Molecules (QTAIM), the structure, the physical nature of chemical bonds and all Bond Critical Points (BCPs) properties have been determined for FOX-7 at the mentioned theoretical levels. Existence of resonance due to "electron-withdrawing" nitro groups and "electron-donating" amine groups in ethene backbone and intra-molecular hydrogen bonding are shown with AIM analysis and then the resonance structures of FOX-7 are found. Also the calculated IR spectrum of FOX-7 is compared with the experimental IR spectrum. It is demonstrated that the mathematical properties of molecular graph derived from charge density analysis are in good correlation with that of the vibrational normal modes derived from ab initio computations.