Study of the CH2NO2 Radical Using a Multiconfigurational Self-Consistent Field Approach.

摘要

The CH2NO2 radical is used as a model for first likely reactive species in the decomposition of high energy materials such as TNT (1,3,5-trinitrotoluene) or HMX (octahydro-1,3,5,7-tetranitro-1,3,5,6-Tetrazocine). Radical species can be observed in an ESR cavity during the inductive phase of decomposition however their identity is not clearly established. Semiempirical, single configurational, and eventually multiconfirgurational ab initio calculations were carried out to determine the ground electronic state and the electronic distribution. Ab initio calculations based on a single configuration plus correlation could not distinguish the ground state. The MCSCF results indicate that the ground state is planar 2A state which results from the interaction of the planar 2B sub 1 and 2A sub 2 states the cross at a common C sub 2V geometry and which leads to a favorable asymmetric distortion from C sub 2V symmetry to a lower C sub S symmetry. A similar distortion was observed by Davidson and coworkers for NO2. The 2A state is 14.6 kcal/mol more stable than the 2B sub 1 state and 19.9 kcal/mol stable than the 2A state. The staggered 2B sub 2 state which is the C sub 2V ground state is 6.8 kcal/mol higher than 2A state. The planar 2A ground state has considerable spin density on the carbon and some on one oxygen in agreement with ESR results.