Carbonato complexes aquation/decarboxylation

The acid catalyzed aquation of the chelated carbonato complexes involves three steps (i) the initial rapid protonation pre-equilibrium of the exocyclic oxygen, (ii) carbonate ring opening, and (iii) decarboxylation of the resulting bicarbonate complex [see Eq. (30)]. 

A number of papers on some transition-metal model complexes have been reported in the literature to mimic the activity of CA and explore further information on the catalytic mechanism of CA. This aspect has been dealt with in Section IV on formation and aquation/decarboxylation of carbonato complexes. A few more relevant... 

The chemistry of aqueous solutions of COj in the presence of aquated transition metal complexes has been extensively studied by a group of researchers led by Harris, Palmer and vanEldik, and they have presented extensive kinetic studies on the carboxylation and decarboxylation of a variety of bis(ethylenediamine)carbonato complexes of The decarboxylation of [Rh(en)2(C03)] ... 

The carbonato complexes undergo aquation to the corresponding aqua complexes by various paths depending on the nature of the complex. This aspect will be discussed briefly for complexes in which carbonate acts as a monodentate and bidentate ligand. The monodentate carbonato complexes of Co, Cr, Rh, and Ir, undergo acid-catalyzed decarboxylation. This can be represented by Eq. (28). 

Acid-catalyzed aquation of [Co(NH3)sOC02], cis-j8-[Co(edda)C03] , and [Co(nta)C03] has been reinvestigated using rapid scan spectrophotometry.Direct spectral evidence for the participation of proton-ated and ring-opened carbonato species was obtained. The spectral observations are consistent with previously suggested mechanisms for the decarboxylation of monodentate and bidentate carbonato complexes. 

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