Carbonato Complexes in Acidic Solution

The reactions of carbonato complexes in basic solution are considered in Section 7.3, and the present section deals with reactions in acidic media. 

The /u.-carbonato complex [(NH3)sCoC03Co(NH3)5](S04)2-4H20 has been characterized and its acid-catalyzed decomposition over the pH range 1-7 studied by flow techniques at / = 0.5 M and The rate-deter- 

At pH 5 values of obs 0 independent of pfl. bove pH 5 values of 4 b fall off rapidly becoming negligible beyond pH 7. The data fit the equation fcobs = fci[H ]/([H ] + X,) with fc, = 1.09 s and X, = 4.4 x 10 M (X, is the acid dissociation of [(NH3)sCoOC02H] ). These values are very similar to those previously determined for the acid-catalyzed decarboxylation of [Co(NH3)sC03r. 

The kinetics of the complete decomposition of cis-[Co(py)2(C03)2] in aqueous HCIO4 have been studied. Decomposition occurs in two successive decarboxylation steps and a final reduction step which gives Co(II) as the only cobalt-containing product. 

The formation kinetics of [Co(NH3)sS03r and trans-[Co(NH3)4(S03)2] have been studied at pH 9 as a function of temperature, pressure, [SOj ], and pH in ammonia buffer solutions. The data obtained can be summarized by equation (8). The k and k terms 

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