Computational study of the C-I bimetallic oxidative addition at Pt-M (M = Ni, Pd and Pt) reaction centers

摘要

Three bimetallic complexes of the type [Me2Pt(mu-bipym)MMe2] (M = Ni, Pd, Pt) in which bipym = 2,2'-bipyrimidine, with a systematic variation in the metals, are chosen to investigate C-I bond activation of MeI through S(N)2-type oxidative addition reactions by using the B3LYP levels of theory. The non-identical dual-core complexes (when M = Pd and Ni) containing two potential nucleophilic centers are theoretically studied to elucidate which center (M or Pt) is the stronger nucleophile toward MeI. The reasons for these two pathways (first attack on Pt, path A, or first attack on M, path B) are discussed based on the energy barrier needed for path A versus path B. On the basis of DFT calculations, in the reaction of complexes Pt-Ni and Pt-Pd with MeI, it is found that these complexes react through Pt(II) at the first step, following by M(II) attacking on carbon atom of MeI to give final Pt(IV)-M(IV) complexes. Also complex [Me2Pt(mu-bipym)NiMe2] is predicted reacting with MeI faster than the others with a lower free energy barrier. Qualitative frontier molecular orbitals for the complexes, energies and main compositions of the relevant frontier orbitals of complexes are also studied. (C) 2019 Elsevier Ltd. All rights reserved.