Self-ionization bromine trifluoride

Considering bromine trifluoride as an example, the self-ionization is shown in equation (1). Dissolution of fluoride acceptors, such as antimony pentafluoride, gives compounds formally containing the difluorobromine(III) cation, and correspondingly, dissolution of fluoride donors, such as potassium fluoride, gives compounds containing the tetrafluorobromate(III) anion. 

Some ionizing solvents are of major importance in analytical chemistry whilst others are of peripheral interest. A useful subdivision is into protonic solvents such as water and the common acids, or non-protonic solvents which do not have protons available. Typical of the latter subgroup would be sulphur dioxide and bromine trifluoride. Non-protonic ionizing solvents have little application in chemical analysis and subsequent discussions will be restricted to protonic solvents. Ionizing solvents have one property in common, self-ionization, which reflects their ability to produce ionization of a solute some typical examples are given in table 3.2. Equilibrium constants for these reactions are known as self-ionization constants. 

Halide donor-acceptor reactions (of XX ) are generally those in which X is donated to or accepted from an interhalogen. They include self-ionization reactions such as that of BrF3 shown in Equation (18.53). This property makes bromine trifluoride a common aprotic (without protons) self-ionizing solvent. In addition to its self-ionization, BrF3 readily accepts fluoride ions from other sources, such as alkali-metal fluorides, to produce salts containing the bromine tetrafluoride ion, as shown in Equation (18.54). Conversely, it can donate fluoride ions to produce salts containing the bromine difluoride cation, as shown in Equation (18.55). 

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