title: Experimental validation of the α-effect in the gas phase.
abstract: The α-effect-enhanced nucleophilicity of an anion with a lone pair of electrons adjacent to the attacking atom-has been well documented in solution; however, there is continuing disagreement about whether this effect is a purely solvent-induced phenomenon or an intrinsic property of the α-nucleophiles. To resolve these discrepancies, we explore the α-effect in the bimolecular nucleophilic substitution reaction in the gas phase. Our results show enhanced nucleophilicity for HOO(-) relative to "normal" alkoxides in three separate reaction series (methyl fluoride, anisole, and 4-fluoroanisole), validating an intrinsic origin of the α-effect. Caution must be employed when making comparisons of the α-effect between the condensed and gas phases due to significant shifts in anion basicity between these media. Variations in electron affinities and homolytic bond strengths between the normal and α-anions indicate that HOO(-) has distinctive thermochemical properties.
authors.affiliation: Department of Chemistry and Biochemistry, University of Colorado, Boulder, 80309-0215, United States.
authors.forename: John M
authors.initials: JM
authors.lastname: Garver
authors.forename: Scott
authors.initials: S
authors.lastname: Gronert
authors.forename: Veronica M
authors.initials: VM
authors.lastname: Bierbaum