Interaction of Dichloromethane with Palladium Complexes: A Comparative Symmetry-Adapted Perturbation Theory, Supermolecule, and Self-Consistent Reaction Field Study

Abstract

This paper reports a theoretical study of the solvent effects on various isomers of the palladium PdH3Cl(NH3)2/[PdH2Cl(NH3)]-(NH4)+ complexes in dichloromethane. The influence of the solvent is investigated by continuum self-consistent reaction field (SCRF) calculations and compared with discrete second-order Møller−Plesset (MP2) calculations. We present a theoretical analysis of the free energy of solvation in the continuum model in terms of the physical contributions (electrostatic, induction, dispersion, and exchange-repulsion) as defined by the symmetry-adapted perturbation theory (SAPT). It is shown that the free energy of solvation in the continuum model correctly accounts for the electrostatic energy and for that part of the induction term which describes the polarization of the solvent by the solute. These theoretical findings are in agreement with the numerical results from the discrete SAPT and continuum SCRF calculations. The global agreement between the SCRF dispersion contribution computed from empirical atom−atom type expressions and the SAPT results is rather good. By contrast, the SCRF exchange-repulsion term is strongly underestimated, which suggests that the parametrization of the SCRF empirical expression is not correct for the palladium compounds. Both the discrete MP2 and continuum SCRF models predict the same relative stabilization for the isomers of the palladium complexes in dichloromethane.