A DFT study on photodissociation of the palladium tetrachloride anion PdCl42− in solution

Abstract

Photodissociation of PdCl42− in water is investigated using the time-dependent DFT method with the polarized continuum model. First, to find out the exchange–correlation functional that can well describe the present system we make following two comparisons using many functionals: (i) the DFT absorption spectrum vs. experiment; (ii) the DFT one-dimensional (1D) potential energy curves (PECs) vs. the previous MRCI 1D PECs. As a result of comparison, it is found that the range-separated hybrid functionals well reproduce the observed spectrum and, among these, the M11 functional may be the most reasonable choice. Next, using M11, we calculate ground and excited-state 1D PECs for single Cl loss in water and the ground-state two-dimensional (2D) potential energy surface (PES) for double Cl loss in water. It is revealed in the 1D PECs in water that electronic excitations to the PECs that have large transition dipole moments with the ground electronic state may easily lead to the PdCl3− + Cl− dissociation channel, which is similar to single Cl loss in the gas phase. It is also found that the ground-state 2D PES in water correlates with the PdCl2 + 2Cl− dissociation channel with no transition state on the way to it. This is different from the prediction in the gas phase; the ground-state 2D PES correlates with the PdCl2 + Cl2− dissociation channel with a transition state on the minimum energy path leading to it.