Theoretical studies of methyl iodide oxidative addition to adjacent metal centers in diplatinum(II) complexes

Abstract

The density functional theory calculations were used to study the electronic and steric effects between two adjacent platinum centers on the oxidative addition of methyl iodide to dimeric complex [Me2Pt(μ-bipym)PtMe2], in which bipym=2,2′-bipyrimidine. A double MeI oxidative addition was considered and the classical SN2 mechanism was suggested for both steps, and the involved transition states and intermediates were proposed. Consistent with the suggested mechanism, large negative ΔS‡ values were found in each step. The calculated energy barrier was larger in the second step as compared to the first step because of the electronic effects transmitted through the 2,2′-bipyrimidine ligand and the steric effects. In a comparative study, the monomeric complex [PtMe2(bipym)] was used in the MeI oxidative reaction as a “calibration reaction” to evaluate the effect of bipym ligand on the rate of the reaction of MeI with dimeric complex, [Me2Pt(μ-bipym)PtMe2].