title: Nucleophilic Substitution in Reactions between Partially Hydrated Superoxide Anions and Alkyl Halides.
abstract: The effect of solvation by water molecules on the nucleophilicity of the superoxide anion, O2(•-), has been investigated in detail by mass spectrometric experiments and quantum chemical calculations, including direct dynamics trajectory calculations. Specifically, the SN2 reactions of O2(•-)(H2O)n clusters (n = 0-5) with CH3Cl and CH3Br were studied. It was found that the reaction rate decreases when the number of water molecules in the cluster increases; furthermore, reaction with CH3Br is in general faster than reaction with CH3Cl for clusters of the same size. In addition, key transition-state geometries were identified and probed by Born-Oppenheimer molecular dynamics, showing how a water molecule may be transferred from the nucleophile to the leaving group during the reaction. The computational models are in good agreement with the experimental observations.
authors.affiliation: †Mass Spectrometry Laboratory and Centre of Theoretical and Computational Chemistry, Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, NO-0315 Oslo, Norway.
authors.forename: Mauritz J
authors.initials: MJ
authors.lastname: Ryding
authors.affiliation: †Mass Spectrometry Laboratory and Centre of Theoretical and Computational Chemistry, Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, NO-0315 Oslo, Norway.
authors.forename: Andrea
authors.initials: A
authors.lastname: Debnárová
authors.affiliation: ‡Departamento de Química Orgánica I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain.
authors.forename: Israel
authors.initials: I
authors.lastname: Fernández
authors.affiliation: †Mass Spectrometry Laboratory and Centre of Theoretical and Computational Chemistry, Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, NO-0315 Oslo, Norway.
authors.forename: Einar
authors.initials: E
authors.lastname: Uggerud