CH3–X Reductive Elimination Reactivity of PtIVMe Complexes Supported by a Sulfonated CNN Pincer Ligand (X = OH, CF3CO2, PhNMe2+)

Three new dihydrocarbyl LPtIVMe­(Y) complexes (6–8; Y = Cl, I, OCH2CF3) supported by the sulfonated CNN pincer ligand L have been prepared and characterized. The reaction of these complexes with a number of nucleophiles (H2O, CF3CO2–, Me2SO, PhNMe2) resulting in the formation of corresponding C–X coupled products CH3–X has been studied in 2,2,2-trifluoroethanol (TFE) and DMSO. In TFE or DMSO solutions at 22 °C, in the presence of PhNMe2, a quantitative formation of a C–N coupled product, PhNMe3+, was observed for 6–8, with the reactivity decreasing in the order 6 > 7 > 8. The use of NaO2CCF3 in TFE solutions was less efficient, leading to the production of MeO2CCF3 in 60% yield after 22 h at 70 °C. In DMSO the C–O coupling was high yielding when aqueous trifluoroacetic acid was used to produce methanol (87% after 3 h at 80 °C) or when NaO2CCF3 was used to form MeO2CCF3 (80% after 1.5 h at 80 °C), with Me3SO+ being a minor byproduct. The kinetics study of the reaction between 6–8 and PhNMe2 in TFE has revealed an overall second-order rate law, d­[PhNMe3+]/dt = k2[6, 7 or 8]­[PhNMe2], consistent with the realization of an SN2-type process. A DFT modeling of several alternative pathways of reaction between 7 and PhNMe2 in TFE supported the direct nucleophilic attack of PhNMe2 at the methyl group carbon of 7 as the most likely mechanism of this transformation.