Results in Chemistry (Dec 2023)
Potential energy surfaces of the Cu2+(MeOH)n=1-8 clusters in solution phase
Abstract
In the present work, we have studied the effects of the implicit solvent on the structural and energetic parameters of Cu2+(MeOH)n=1-8 clusters. Initially, we explored the potential energy surfaces (PESs) obtained in the solution phase using the functional DFT M06-2X method, in conjunction with the 6–31++G** Pople basis set, and compared them with isomers of the same complexes optimized in the gaseous phase. The implicit solvent is described here by the polarized continuum model of integral equation formalism (IEF-PCM). Subsequently, we reported the temperature dependence and the binding electronic energies per methanol molecule. Our investigations reveal that the 6- and 5-coordinate isomers occupy the ground states on the PESs of the Cu2+(MeOH)n=1-8 clusters. The stability rules of the Cu2+ ion established in the gas phase are best adhered to in the implicit solvent. Regarding the temperature dependence of the solution phase conformer distribution, symmetric and compact structures, as well as those with a high coordination number (CN), dominate the population of the Cu2+(MeOH)n=1-8 clusters at all temperatures. Notably, the populations of clusters with sizes n=7-8 are exclusively dominated by hexa-coordinated structures at all temperatures, while penta- and tetra-coordinated isomers are disadvantaged. For the determination of the binding electronic energy, using a function fit, we computed these energies to be -1589kJ mol−1 in the implicit solvent and -7150kJ mol−1 in the gaseous phase. This significant difference is attributable to the interactions between the methanol molecules and the implicit solvent, which are present in the solvent phase but absent in a gaseous medium. This difference is further supported by the analysis of the Wiberg bond index of the metal–ligand interactions of the clusters in the two media.
