Studies on the Synthesis of Metal Complexes. I. Synthesis of an Ammine-carbonato Series of Cobalt (III) Complexes

A green compound is isolated from the concentrated solution obtained by the action of hydrogen peroxide on cobalt (II) ions in the presence of potassium bicarbonate, and the formula K3[Co(CO3)3]·3H2O is assigned to it on the basis of the analysis of the solid and of the absorption spectrum of the solution. A series of ammine-carbonatocobalt (III) complexes, K3[Co(CO3)3]·3H2O, blue (perhaps, cis) and violet(perhaps, trans)-K[Co(NH3)2(CO3)2]·H2O, [Co(NH3)4CO3]Cl and [Co(NH3)6]Cl3, are synthesized from the abovementioned green solution by means of successive substitution of carbonate ions by ammonia groups. Hexamminecobalt (III) tricarbonatocobaltate, [Co(NH3)6] [Co(CO3)3], is also obtained by adding a hexamminecobalt (III) salt to the green solution of tricarbonato-complex. Three complexes, K3[Co(CO3)3]·3H2O and blue- and violet-K[Co(NH3)2(CO3)2]·H2O, are probably to be regarded as new complexes and may be identified by their absorption spectra.