Interaction of dichloromethane with the coordination sphere of palladium complexes: Toward a first solvation shell model

In this paper we report a theoretical study of the: solvent effects on vari ous isomers of the palladium PdH3Cl(NH3)(2)/[PdH2Cl(NH3)](-)(NH4)(+) comple xes 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-repulsio n contributions as defined by the symmetry-adapted perturbation theory (SAP T). The importance of various contributions to the solute-solvent interacti on energy can be correlated with the chemical properties of the ligand to;w hich 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 p ropose a model for the first solvation shell composed of six solvent molecu les. We checked that some changes in the geometry of the first solvation sh ell 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.