The theoretical study on structure and property of diamino-dinitroethylene

1,1 - Diamino - 2,2 - dinitroethylene recently synthesized is a new energet ic compound, which may be an insensitive high explosive (ME). In this paper , the fully optimized molecular geometries and the total energies of diamin o - dinitroethylene compomnds, 1,1 - diamino - 2,2 - dinitroethylene ( I), cis ( II) and trans (III) 1,2 - diamino - 1,2 - dinitroethylene, have been calculated using ab initio method at the HF/6 - 31G**, MP2/6 - 31G**//HF/6 - 31G** level and DFT method at B3LYP/6 - 31G** level, respectively. The re sult shows that the order of stability of the title compounds is I > III > II, thermodynamically. There exist strong intramolecular hydrogen bonds bet ween nitro oxygen atoms and amino hydrogen atoms of the titled compounds an d the hydrogen bond intensities of the title compounds are I > III > II. Th eir frontier orbital energy gaps (DeltaE) are I > II > III. Based on the an alysis of molecular geometry and frontier orbital component, it is found th at the pi - electron conjunction and delocalization of the title compounds are I approximate to III > II. The computed vibrational frequencies of 1,1 - diamino - 2,2 - dinitroethylene is in good agreement with the correspondi ng experiment results. The thermodynamic properties of DADNE were