Stable trans isomer as the kinetic and theromodynamic product for the oxidative addition of MeI to cycloplatinated(II) complexes comprising isocyanide ligands

The present investigation introduces a new series of cycloplatinated(II) complexes, with the general formula Pt(O-bpy)(Me)(CN-R)] (R = benzyl, 2-naphtyl and tert-butyl), which are able to generate the stable trans-Pt(IV) product in the solution after the reaction with iodomethane. In fact, the trans product is both the kinetic and thermodynamic product of the reaction; this observation was supported by DFT calculations. These Pt(II) complexes are supported by 2,2'-bipyridine N-oxide (O-bpy) and one of several isocyanides as the cyclometalated and ancillary ligands, respectively. These new Pt(II) complexes undergo oxidative addition with MeI to give the corresponding trans-Pt(IV) complexes. All the complexes were identified employing the multi-nuclear NMR spectroscopy and single crystal X-ray crystallography. The kinetic investigations were also performed for the oxidative addition reactions in order to measure the reaction rates; the reaction was followed by UV-Vis spectroscopy. The rates obtained follow the trend CN-^tBu > CN-Bz > CN-2 Np for the CN-R ligands in the Pt(II) complexes. The order can be related to the degree of electron-donation of the R group (tert-butyl > benzyl > 2-naphtyl).