Zur Kenntnis der Sulfito-kobalt(III)-Ammine. I. Sulfitopentammin- und Sulfitoaquotetramminkobalt(III)-Salze

Sulphito Cobalt (III) Ammines. I. Sulphitopentaamminecobalt (III) and Sulphitoaquotetraamminecobalt(III) Salts Because of the trans effect of the sulphito group salts containing the cation [CoSO₃(NH₃)₅]⁺ react with H₂O forming [CoSO₃H₂O(NH₃)₄]⁺. In acid medium the conversion is complete. Therefore, sulphitopentaamminecobalt(III) salts have to be prepared and purified in solutions containing free ammonia. Earlier preparation methods not regarding this circumstance lead to tetraammine compounds or to mixture of pentaammine and tetraammine complexes. The preparation and the properties of a number of sulphitopentaammine and sulphito-aquotetraamminecobalt(III) salts are described (see “Inhaltsübersicht”). The light absorption and the IR spectra of the complexes [CoSO₃(NH₃)₅]⁺ and [CoSO₃H₂O(NH₃)₄]⁺ are reported and discussed.