Oxidation of Methylplatinum(II) Complexes K[(L)PtIIMe] with O2 and C(sp3)‑X (X = O and C) Reductive Elimination Reactivity of Methylplatinum(IV) Products (L)PtIVMe(OH): The Effect of Structure of Sulfonated CNN-Pincer Ligands L

Two sulfonated CNN-pincer ligands L1 and L2 were used to explore the oxidative functionalization of the PtII-Me bond in derived K­[(L)­PtIIMe] complexes (L = L1 and L2) using O2 and H2O2 as oxidants (HL1– = (6-phenylpyrid-2-yl)­(pyrid-2-yl)­methanesulfonate; HL2– = (6-phenylpyrid-2-yl)-6,7-dihydro-5H-cyclopenta [b]­pyridine-7-sulfonate). Oxidation with O2 of K­[(L1)­PtIIMe] in MeOH produced a single high-valent platinum complex, (L1)­PtIVMe2, whereas the use of H2O2 led to (L1)­PtIVMe­(OH), 10c, and (L1)2PtIV 2Me2(μ-OH)2, 14, having different configurations of a PtIV center. Oxidation of a more rigid analog, K­[(L2)­PtIIMe], with O2 led to diastereomeric complexes (L2)­PtIVMe­(OH), 11d, in MeOH and 11a (detected as an adduct with the CF3CH2O– anion) in acetone/2,2,2-trifluoroethanol mixtures. The use of H2O2 led to (L2)­PtIVMe­(OH), 11c, and (L2)2PtIV 2Me2(μ-OH)2, 15, the analogs of 10c and 14, respectively. When heated with CF3CO2H in aqueous DMSO, MeOH, or acetone at 80 °C, (L)­PtIVMe­(OH) complexes produced in high yield either MeOH and MeO2CCF3 or C­(sp2)-C­(sp3) coupled products involving a carbon atom of pincer ligands. DFT calculations were used to analyze the observed reactivity. It was concluded that the key factors favoring the C­(sp3)-O coupling are the trans-arrangement of the methyl ligand and the sulfonate group, the use of CF3CO2 – as an O-nucleophile and DMSO as a solvent favoring the generation of highly electrophilic PtIVMe intermediates.