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Thermal decompositions of the trans-[Co(en)2Cl2]Cl and cis-[Co(en)2Cl2]Cl complex isomers have been studied using the TG–FTIR and TG–DSC–MS techniques. The measurements were carried out in argon atmosphere over the temperature range 293–873 K. The influence of the configurational geometry on the pathways of thermal transformations was discussed. Furthermore, kinetic studies on the reaction of the cis–transisomerization of the [Co(en)2Cl2]Cl complex salt in methanolic solutions were performed using UV–Vis spectrophotometry at five temperatures in the 293–313 K temperature range. The observed rate constants were computed using the “Glint” program based on the global analysis. It has been found that the cis–transisomerization of [Co(en)2Cl2]Cl is a first order reaction. Furthermore, the cis/trans[Co(en)2Cl2]Cl isomerization proceeds according to the dissociative mechanism.

Abstract: This study has demonstrated the direct formation of CO2 during the decomposition of the cis-[Cr(C2O4)(PM)(CO3)]− complex anion after addition of perchloric acid to the aqueous solution of this ion. Thus, the studied coordination species can be successfully used as a source of CO2 under specific conditions. This conclusion has been drawn from results of the kinetic studies of acid hydrolysis of the cis-[Cr(C2O4)(PM)(CO3)]− anion. This reaction was investigated using the stopped-flow technique. The measurements were carried out at temperatures ranging from 5 to 25 °C and in [H+] concentrations 0.01, 0.05, 0.1, 0.3, 0.5, 0.8, 1.1, 1.4, 1.7, and 2.0 M. The decarboxylation mechanism for the studied coordination compound has been proposed.