Selectivity and competition between N–H and C–H bond activation using an organoplatinum (II) complex

Abstract

2‐(2′‐Pyridyl)benzimidazole (Hpbz), containing both C–H and N–H bonds available for activation, has been investigated to elucidate which bond is activated upon coordination to the Pt(II) precursor complex (PtMe2(DMSO)2), 1. On the basis of density functional theory (DFT), Hpbz is predicted to react with 1 through N–H bond activation of the benzimidazole ring in preference to C–H bond activation of the pyridine ring. The reasons for this difference in selectivity are discussed based on the energy barrier needed for N–H versus C–H bond activation. The DFT results are in agreement with experimental findings in which reaction of Hpbz with 1 at room temperature leads to N–H bond activation to give (PtMe(pbz‐κ2‐N,N)(DMSO)), 2. The kinetic and mechanistic study of the reaction between Hpbz and 1 shows that the reaction occurs through substitution of one DMSO by the nitrogen atom of pyridine ring of Hpbz to give (PtMe2(Hpbz‐κ1N)(DMSO)), followed by N–H activation and release of methane to form 2.