STUDIES ON THE INTERACTION OF SELENITE AND SELENIUM WITH SULFUR DONORS .3. SULFITE

Elemental selenium dissolves in sulfite solution to form selenosulfate ion: Se + SO32- = SeSO32-. The formation constants for this equilibri um at temperatures from 0 to 35 degrees C are reported for the first t ime. The isomeric thioselenate anion, SSeO32-, is not, however, produc ed by the reaction of sulfur with selenite nor is the selenoselenate i on, Se2O32-, formed from selenium and selenite. Selenotrithionate is f ormed rapidly from the reaction of selenous acid with sulfite and hydr ogen sulfite according to: HSeO3- + 3 HSO3- = Se(SO3)(2)(2-) + SO42- 2 H2O. Two isomers of the selenotrithionate ion are observed by Se-77 NMR and Raman spectroscopy, one with O-bonded Se, Se(OSO2)(2)(2-), an d the other with S-bonded Se, Se(SO3)(2)(2-). Both isomers are formed in reactions with hydrogen sulfite but only the O-bonded isomer is for med in sulfite solutions at ambient temperatures. The Raman and Se-77 NMR spectra of the various sulfur-selenium anions formed are given and the parallel with the reactions of selenous acid and thiols is discus sed.