Fluoro anions, very weakly basic

These complex anions are very weakly basic, i.e. of very low nucleophilicity, and have been used deliberately as counter-ions in the isolation of solid compounds where the cation is highly electrophilic and subject to disproportionation or other reaction with species of reasonable base strength. Relative basicities of anions can be of great importance in isolating such compounds. An example which will be discussed in detail in Sec. 11.3.4.6 involved attempts to synthesise solid compounds of IJ and BrT. These were unsuccessful when the counter-ion was fluorosulfate, because of disproportionation of the halogen cations, whereas the cations were stable in the presence of less basic fluoro-antimonates. 

Stabilization of Unusual Cations by Very Weakly Basic Fluoro Anions... 

Ag ", stabilization by very weakly basic fluoro anions, 355-357 Alkali and alkaline earth fluoroalkoxides, chemistry, 406r... 

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