title: Multiconfigurational second-order perturbation study of the decomposition of the radical anion of nitromethane.
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.
authors.affiliation: Department of Physical Chemistry, Faculty of Sciences, University of Malaga, E-29071-Malaga, Spain. arenas@uma.es
authors.forename: Juan F
authors.initials: JF
authors.lastname: Arenas
authors.forename: Juan C
authors.initials: JC
authors.lastname: Otero
authors.forename: Daniel
authors.initials: D
authors.lastname: Peláez
authors.forename: Juan
authors.initials: J
authors.lastname: Soto
authors.forename: Luis
authors.initials: L
authors.lastname: Serrano-Andrés