Derivatographic Studies on Transition Metal Complexes. VI. Thermal, cis, trans-to-cis, cis Exchange-Isomerization of [CoCl2(NH3)2en]SCN·H2O in Solid Phase

Abstract

Abstract The exchange-isomerization of the complex, cis(dichloro), trans(diammine)-[CoCl2(NH3)2en]SCN·H2O to cis(chloro isothiocyanato), cis(diammine)-[CoCl(NCS)(NH3)2en]Cl, was investigated by means of both derivatographic and isothermal methods. The reaction took place immediately after the liberation of crystalline water. The thermochemical functions were obtained to be ΔH=(5.5±1.0) kcal/mol and E≠=(22.8±2.0) kcal/mol for the dehydration, while those for the exchange-isomerization were ΔH=(4.8±1.0) kcal/mol and E≠=(62.3±3.0) kcal/mol, respectively. As a probable reaction mechanism for the exchange-isomerization, a certain seven coordinated intermediate in the reaction pathway was introduced.