The fluorosulfates or fluorosulfonates are a set of salts of fluorosulfuric acid with an ion formula SO3F−.
[1] The fluorosulfate ion has a low propensity to form complexes with metal cations.
[3] The fluorosulfate anion is weakly coordinating, and is difficult to oxidise.
It is important historically as a model weakly coordinating anion.
Nonmetal pseudobinary fluorosulfates are known including those of halogens and xenon.