Activation of C−F and C−H Bonds by Platinum in Trifluorinated [C,N,N‘] Ligands. Crystal Structures of [PtFMe2{Me2NCH2CH2NHCH(CH2COMe)(2,4-C6H2F2)}] and [PtMe{Me2NCH2CH2NCH(2,3,4-C6HF3)}

Abstract

Trifluorinated ligands Me2NCH2CH2NCHR (R = 2,4,6-C6H2F3 (2a), 2,3,6-C6H2F3 (2b)) react with [Pt2Me4(μ-SMe2)2] (1) to yield the [C,N,N‘] saturated cyclometalated platinum(IV) compounds [PtFMe2{Me2NCH2CH2NHCH(CH2COMe)(C6H2F2)}] (4) arising from CF bond activation followed by acetone addition on the iminic bond of the coordinated ligand. The reactions of the platinum substrate with trifluorinated ligands Me2NCH2CH2NCHR (R = 2,3,4-C6H2F3 (2c), 2,4,5-C6H2F3 (2d), 3,4,5-C6H2F3 (2e)) containing only one or no fluorine atom in the ortho positions yield the [C,N,N‘] cyclometalated platinum(II) compounds [PtMe(Me2NCH2CH2NCHC6HF3)] (5) by ortho metalation with loss of methane. Compounds 5 react with methyl iodide to yield the [C,N,N‘] unsaturated cyclometalated platinum(IV) compounds [PtIMe2(Me2NCH2CH2NCHC6HF3)] (6) and with triphenylphosphine to produce the displacement of the NMe2 moiety and the formation of [C,N] cyclometalated compounds [PtMe(PPh3)(Me2NCH2CH2NCHC6HF3)] (7c). When there is a fluorine atom adjacent to platinum (F5), the displacement of both nitrogen donor atoms takes place upon reaction with PPh3 to yield the compounds [PtMe(PPh3)2(Me2NCH2CH2NCHC6HF3)] (7d,e). All compounds were characterized by elemental analyses and NMR spectroscopy, and [PtFMe2{Me2NCH2CH2NHCH(CH2COMe)(2,4-C6H2F2)}] (4a) and [PtMe{Me2NCH2CH2NCH(2,3,4-C6HF3)}] (5c) were characterized crystallographically.