Tetraethylenepentamine cobalt complex

The kinetic effects of C02 in the base catalyzed hydrolysis of some carboxylato amine cobalt(III) complexes have been reported (80-82). In the base catalyzed hydrolysis of oxalatopentaammine-cobalt(III) (80), C02 retarded the reaction due to the formation of a virtually unreactive ion-pair, f (N H .) r, 2 2 COi ]. The equilibrium constant for formation of carbonate ion-pairs with (glycinato-O) (tetraethylene-pentamine)cobalt(III), (81) and (o-methoxybenzoato) (tetraethylenepentamine)cobalt(III) (82) were, however, much smaller than for the oxalatopentamminecobat(III) and a very weak rate retardation and virtually no effect was observed in the base catalyzed hydrolysis of the latter two complexes. 

Rapid scan spectrophotometry has been used to study the base hydrolysis of ajS5-(salicylato)(tetraethylenepentamine) cobalt(III) (17). The instantaneous color change observed on addition of base to the complex has been attributed to formation of the phenoxide species and this point has been confirmed. Subsequent aquation and base hydrolysis of the phenoxide species then occurs with = 0.116 s and /cqh = 3.32 M s at 25"C. 

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