Intermolecular interactions of dichloromethane with Pd(IV) organometallic compounds: can we use small basis sets in ab initio MP2 and DFT calculations?

Abstract

The interaction of CH 2Cl 2 with the different ligands of PdCl(H) 3(NH 3) 2 is studied, showing the effect of the level of the method used, together with that of the basis sets employed in ab initio calculations. The position of the minimum, generally determined without BSSE correction by the gradient geometry optimization method in supermolecule treatment, has been systematically reoptimized pointwise with a counterpoise BSSE correction. It is seen that the change of the minimum is much larger with MP2 than with DFT calculations. The DFT geometry obtained without BSSE correction is close to the BSSE-corrected MP2 one. However, the BSSE-corrected DFT and MP2 interaction energies may differ by as much as 50%, the MP2 energies being in good agreement with MP4(SDTQ) results. The strategy of a low-cost DFT(B3LYP) optimization of the geometry followed by the computation of the BSSE-corrected MP2 energies appears to be reliable in this type of investigation.