Synthesis of a series of PNC pincer ligand-supported Pt complexes, and an initial exploration of their reactivity

A Pt-Cl complex supported by a PNC (phosphine, pyridine, and phenyl) donor pincer ligand was synthesized. The complex proved to be remarkably stable under air and ambient conditions. Cationic complexes with coordinated DMSO or CO were obtained from the initial (PNC)-Pt-Cl, with all the complexes characterized structurally and spectroscopically. The chloro-complex could also be converted into a neutral complex with the associated hydride or a methyl ligand which were isolated and fully characterized by NMR, and their dearomatized anionic congeners which were characterized by NMR <i>in situ</i>. As expected, all neutral complexes could be dearomatized by addition of a base. An unexpected K⁺ zwitterionic bound structure was obtained for the starting, dearomatized PNC-Pt-Cl complex. This species could not be induced to lose the Cl ligand, but the bound K counterion was easily removed by protonation of the ligand arm, regenerating the starting material. A (PNC)-Pt-CF₃ complex showed indications of sub-stoichiometric CH activation of benzene solvent.