1. Multiconfigurational second-order perturbation study of the decomposition of the radical anion of nitromethane
- Author
-
Juan F. Arenas, Juan C. Otero, Daniel Peláez, Luis Serrano-Andrés, and Juan Soto
- Subjects
Potential Energy Surfaces ,Nitromethane ,Organic Compounds ,General Physics and Astronomy ,Negative Ions ,Dissociation ,Ion-Molecule Reactions ,Perturbation Theory ,Density Functional Theory ,SCF Calculations ,Potential energy ,Dissociation (chemistry) ,UNESCO::FÍSICA::Química física ,Ion ,chemistry.chemical_compound ,chemistry ,Computational chemistry ,Density functional theory ,Symmetry breaking ,Physical and Theoretical Chemistry ,FÍSICA::Química física [UNESCO] ,Isomerization ,Chemical decomposition - Abstract
The doublet potential energy surfaces involved in the decomposition of the nitromethane radical anion (CH(3)NO(2) (-)) have been studied by using the multistate extension of the multiconfigurational second-order perturbation method (MS-CASPT2) in conjunction with large atomic natural orbital-type basis sets. A very low energy barrier is found for the decomposition reaction: CH(3)NO(2) (-)--[CH(3)NO(2)](-)--CH(3)+NO(2) (-). No evidence has been obtained on the existence of an isomerization channel leading to the initial formation of the methylnitrite anion (CH(3)ONO(-)) which, in a subsequent reaction, would yield nitric oxide (NO). In contrast, it is suggested that NO is formed through the bimolecular reaction: CH(3)+NO(2) (-)--[CH(3)O-N-O](-)--CH(3)O(-)+NO. In particular, the CASSCF/MS-CASPT2 results indicate that the methylnitrite radical anion CH(3)ONO(-) does not represent a minimum energy structure, as concluded by using density functional theory (DFT) methodologies. The inverse symmetry breaking effect present in DFT is demonstrated to be responsible for such erroneous prediction.
- Published
- 2004