The addition of SO2 tocis-(hydroxo) (imidazole)bis(ethylenediamine) cobalt(III) ion-generated-oxygen-bonded sulphito complex, the kinetics of which have been studied by the stopped-flow technique. The rate and activation parameters for the formation ofcis-[(en)2(imH)CoOSO2]+, the elimination of SO2 from this O-bonded sulphito species which is H+-catalysed and of second order, and formation of the corresponding carbonato complexcis-[(en)2(imH)CoOCO2]+, by the reaction of CO2 withcis-[(en)2(imH)CoOH] have been determined. The bicarbonato complex,cis][(en)2(imH)CoCO2H]2+, undergoes spontaneous CO2 elimination. The relatively low ΔH‡ and large negative values of ΔS‡ for CO2 uptake bycis-[(en)2(imH)CoOH]2+ are in contrast to the values for other analogous complexes of cobalt(III) reported in the literature. Some specific effects of cobalt(III)-bound imidazole on CO2-addition processes have been inferred.
Volume 134, 2022
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