Interaction of Dichloromethane with the Coordination Sphere of Palladium Complexes: Toward a First Solvation Shell Model

摘要

In this paper we report a theoretical study of the solvent effects on various isomers of the palladium PdH_3-Cl(NH_3)_2/[PdH_2Cl(NH_3)]~-(NH_4)~+ complexes in dichloromethane. The solute-solvent interactions are investigated by discrete second-order Moller-Plesset (MP2) calculations and characterized in terms of the electrostatic, induction, dispersion, and exchange-repulsion contributions as defined by the symmetry-adapted perturbation theory (SAPT). The importance of various contributions to the solute-solvent interaction energy can be correlated with the chemical properties of the ligand to which the solvent molecule is attached. They are ligand dependent. However, the sum of these contributions (i.e., the total solvent-solute interaction for each ligand) is nearly isotropic around the solute. This allows us to propose a model for the first solvation shell composed of six solvent molecules. We checked that some changes in the geometry of the first solvation shell do not significantly alter the total interaction energy with the solute. The qualitative results are not significantly affected if the interaction energy is approximated by the sum of the solute-solvent pairs energies.