Electronic Structure and Reactivity of Dioxygen-Platinum Complexes: an ab Initio MO-LCAO Study

Ab initio Hartree Fock calculations have been carried out on the complex L2Pt(η2-O2) and its derivatives L2Pt-(OOH)X and L2Pt(OOH)(XY) obtained by reaction with HX (HX = H2O, HCl, HOOCH, NH3) and HXYH (HXYH = oxalic acid, o-catechol, hydrazine, hydroxylamine, ethylendiamine, o-phenylendiamine). In addition also the reaction L2Pt(OOH)X + HX → H2O2 + L2PtX2 leading to the formation of hydrogen peroxide has been studied. The theoretical investigation gave, for all considered species, optimum complex geometry, charge distribution and reaction energies being evaluated by means of a correlation energy density functional. The ability of the HX reagents to form hydrogen peroxide is discussed in terms of absolute acidity and coordinating capability of the X- groups. This allows interpretation of the more peculiar aspects of the chemical activation of dioxygen that leads to the coordinated hydroperoxide species or hydrogen peroxide.