Reactivity of phosphines with iodomethane analog fluoroiodomethane

Reactions of phosphines with iodomethane are well known and well investigated. The resulting phosphonium salts are used in Wittig reactions or to form ionic liquids. Reaction rates depend on the Tollman parameter as well as on steric factors. Reactions with iodomethane occur spontaneously within a few hours. We have found that the corresponding reactions of phosphines with fluoroiodomethane are significantly slower. Reaction times range from one day up to 11days. The resulting phosphonium salts are stable towards air and water and show also low aqueous toxicity with respect to Vibrio fisheri bacteria. Due to the strong electronegativity of the fluorine atom and its similarity to an OH group, interesting crystal structures were observed. [GRAPHICS] .