Evidence for a Symmetrical Fluoronium Ion in Solution

Abstract

Fluorine Learns to Share Though halides typically coordinate to just one carbon center, their transient coordination to a second carbon (forming a positively charged bridge) explains the spatial dynamics of many reactions. However, unlike chlorine, bromine, and iodine—which can all form such halonium ions—fluorine does not appear to engage in carbon-bridging behavior, presumably because of its very high electronegativity. Struble et al. (p. 57 , see the Perspective by Hennecke ) synthesized a rigid molecule, particularly well-poised to manifest fluoride bridging, and provide evidence for a fluoronium intermediate in a displacement reaction.