title: An interpretation of the phenol nitration mechanism in the gas phase using G3(MP2)//B3-CEP theory.
abstract: G3(MP2)//B3-CEP theory was applied to study the mechanism of phenol nitration in the gas phase, as promoted by the electrophile NO2 (+). The results of studying this mechanism at the G3(MP2)//B3-CEP level pointed to the occurrence of a single-electron transfer (SET) from the aromatic π-system to the nitronium ion prior to σ-complex formation. The formation of an initial π-complex between the nitronium ion and phenol was not observed. Excellent agreement between the activation barriers predicted by G3(MP2)//B3-CEP and those yielded by other, more accurate, versions of the G3 theory showed that the former is a useful tool for studying reaction mechanisms, as G3(MP2)//B3-CEP is much less computationally expensive than other high-level methods.
authors.affiliation: Departamento de Química, Universidade de Coimbra, 3004-535, Coimbra, Portugal.
authors.forename: Carlos Murilo Romero
authors.initials: CM
authors.lastname: Rocha
authors.forename: José Augusto Rosário
authors.initials: JA
authors.lastname: Rodrigues
authors.forename: Paulo José Samenho
authors.initials: PJ
authors.lastname: Moran
authors.forename: Rogério
authors.initials: R
authors.lastname: Custodio