MODELING OF THE BIS(GLYCINATO)COPPER(II) CIS-TRANS ISOMERIZATION PROCESS: THEORETICAL ANALYSIS

In a number of theoretical works, the cis-trans isomerization of bis(glycinato)copper(II) and its interaction with water molecules is investigated. The interactions with the water medium modeled either by adding water molecules explicitly or through the Polarized Continuum Model (PCM) are investigated by the density functional (B3LYP) method in order to question the reliability of theoretical results. The crucial dependence of theoretical energies on the accuracy of PCM corrections is established. It is shown that for bis(glycinato) copper(II) the differences of isomer energies are of the order of the upper limit of the reliability of PCM corrections. Based on the calculation results, two possible mechanisms for the cis-trans isomerization are proposed. It is shown that only the inclusion of two explicit water molecules enables the modeling of the isomerization mechanism involving the interchange of glycine and water oxygen atoms in copper coordination.