Hydration and `inverse hydrationʹ of platinum(II) complexes: an analysis using the density functionals PW91 and BLYP

The interaction between two platinum complexes and water was investigated using the DFT functionals PW91 and BLYP. Previous MP2 and HF calculations have shown that when a H2O molecule approaches Pt with its O atom, the interaction is governed by electrostatics and the MP2 and HF interaction energy curves nearly coincide, whereas for the approach with H pointing towards Pt, there is a significant dispersion component portrayed only by MP2 calculations. Here we show that both PW91 and BLYP satisfactorily reproduce the MP2 curves, PW91 slightly exaggerating and BLYP slightly underestimating the dispersion-induced energy minima. This result is discussed in view of the different behavior of the two exchange functionals at large density gradients.