Hyposulfite, SO22−, was reported as a sulfur oxoanion. However salts containing SO22− and the corresponding acid, hyposulfurous acid (H2SO2) are not believed to exist. The word hyposulfite is also a synonym for the thiosulfate ion, S2O32−. As opposed to hydrosulfite which is a synonym for the dithionite ion, S2O42−. Related sulfur oxoanions SO52− persulfate ion SO42− sulfate ion SO32− sulfite ion… (More on Hyposulfite)