Cyclometallated platinum compounds with N-benzylidenebenzylamines bearing trifluoromethyl groups. Crystal structure of [PtMe{3-(CF3) C6H3CH=NCH2Ph(PPh3)]

Article abstract of DOI:10.1016/S0277-5387(97)00452-X

The reaction of [Pt₂Me₄(μ-SMe₂)₂] (1) with the imine 3-(CF₃)C₆H₄CH=NCH₂Ph (2a) yields the cyclometallated compound [PtMe{3-(CF₃)C₆H₃CH=NCH₂Ph}(SMe ₂)] (3a) by selective metallation at the less hindered of the two ortho positions of the aryl ring followed by loss of methane. A similar reaction for imine 2-(CF₃)C₆H₄CH=NCH₂Ph (2c) yields the cyclometallated compound [PtMe{2-(CF₃)C₆H₃CH=NCH₂Ph} (SMe₂)] (3c). The reactions of these compounds with triphenylphosphine in (1 : 1) ratio produce compounds [PtMe(3-(CF₃)C₆H₃CH=NCH₂Ph}(PPh ₃)] (4a) and [PtMe{2-(CF₃)C₆H₃CH=NCH₂Ph}(PPh ₃)] (4c). The X-ray structure of 4a is reported. An excess of triphenylphosphine produces metallacycle cleavage and [PtMe{3-(CF₃)C₆H₃CH=NCH₂Ph}(PPh ₃)₂] (5a) is formed with the imine acting as a [C^....] unidentate ligand. Oxidative addition of methyl iodide to compounds 4a and 4c gives cyclometallated platinum(IV) complexes. Imines 3,5-(CF₃)₂C₆H₃CH=NCH₂Ph (2b) and 2-F-6-(CF₃)C₆H₃CH=NCH₂Ph (2d) fail to react with [Pt₂Me₄(μ-SMe₂)₂] (1).