Computational studies on a kind of novel energetic materials tetrahedrane and nitro derivatives

The computational studies on a series of nitro derivatives of tetrahedrane are carried out at B3LYP/aug-cc-pvdz level. The molecular geometries are optimized and the vibrational frequencies are calculated. The electronic structures are analyzed using natural bond orbital theory and atoms in molecules theory. The results show that the skeleton, tetra-carbon cage, is subject to the large stress, C-C bonds of which are weaker than normal C-C bond. The introduction of nitro group reduces the stability of tetra-carbon cage and the C-N bond is weak. The more nitro groups are introduced, the weaker the C-N bonds are. Due to the charge transfer from lone pairs on oxygen to σ*(C-N), the C-N bond possesses some π-bonding characteristic and is activated. For C₄(NO₂)₄, the C-N bond is more readily broken than the C-C bond. Heats of formation (HOFs) of nitro derivatives are calculated by isodemic reactions. Values of obtained HOFs are all positive and large so they are belonging to endothermic materials. The HOFs increase with the increase on the number of nitro groups. The results show that these kind of compounds possess some properties of energetic materials and polynitrotetrahedrane may be the potential candidates of the powerful energetic material. © 2004 Elsevier B.V. All rights reserved.