Behavior of the bischelate platinum(II) complexes [Pt(S^N)(C^N)] (S^N = pyridine-2-thionate, C^N = 2-phenylpyridinate or benzo[h]quinolate) toward C–I bond activation; a DFT study

Abstract

The oxidative addition reactions of RI (R = CH3 or C2H5) to the [Pt(S^N)(C^N)] complexes (S^N = pyridine-2-thionate, C^N = 2-phenylpyridinate or benzo[h]quinolate) were theoretically investigated using density functional theory calculations to gain more insight into the mechanism of the reactions, as well as to try and determine the geometry of the transition states and energy barriers. The DFT study suggested the formation of transition states including Pt…C(R)…I fragments, followed by the formation of the ionic five-coordinate [PtR(S^N)(C^N)]+I− intermediates with the R group in the apical position and with the iodide ion out of coordination sphere of Pt center. The DFT studies were in agreement with the experimental finding and showed that the nature of R group in alkyl halide had a significant influence on the energy barriers of the reactions, but the nature of C^N chelate ligand does not change significantly the energy barrier of oxidative addition when R is constant.