The Relation between the Geometrical Configurations of Inorganic Complexes and their Absorption Bands. II. The Configurations of Two Isomers of Sodium Disulfono-tetrammine-cobaltiate

The visible and ultra-violet absorption spectra of Na[Co(NH3)4(SO3)2]·2H2O (brown salt) and Na[Co(NH3)4(SO3)2]·4H2O (yellow salt) have been measured. The results have proved that the SO3=-radical coördinates around the central cobalt (III) ion by the lone pair electrons of its sulfur atom, and that the brown salt has trans-configuration concerning the positions of the SO3=-radicals and the yellow salt cis-configuration. The absorption spectrum of NH4[Co(NH3)4(SO3)2]·3H2O (dark brown form) has also been studied and it has been assumed that the salt is trans-isomer contrary to several investigators’ assignmints of cis-strusture.