Regioselective activation of CH bonds of naphthyl imines at platinum(II). Crystal structures of [PtMe{1-(2′-ClC6H4CH2NCH)C10H6}PPh3] and [PtMe{2-(2′-ClC6H4CH2NCH)C10H6}PPh3]

The reaction of [Pt2Me4(μ-SMe2)2] with ligands 1-(Me2NCH2CH2NCH)C10H7 (2a) and 2-(Me2NCH2CH2NCH)C10H7 (2b) carried out in acetone at room temperature produced compounds [PtMe2{1-(Me2NCH2CH2NCH)C10H7}] (3a) and [PtMe2{1-(Me2NCH2CH2NCH)C10H7}] (3b), respectively, in which the imines act as bidentate [N,N′] ligands. Cyclometallated [C,N,N′] compounds [PtMe{1-(Me2NCH2CH2NCH)C10H6}] (4a) and [PtMe{2-(Me2NCH2CH2NCH)C10H6}] (4b) were obtained by refluxing toluene solutions of compounds 3a or 3b. Reaction of [Pt2Me4(μ-SMe2)2] with ligands 1-(2′-ClC6H4CH2NCH)C10H7 (2c) and 2-(2′-ClC6H4CH2NCH)C10H7 (2d) produced straightforward metallation to yield [PtMe{1-(2′-ClC6H4CH2NCH)C10H6}SMe2] (5c) and [PtMe{2-(2′-ClC6H4CH2NCH)C10H6}SMe2] (5d) containing a [C,N] ligand. Triphenylphosphine derivatives [PtMe{1-(2′-ClC6H4CH2NCH)C10H6}PPh3] (6c) and [PtMe{2-(2′-ClC6H4CH2NCH)C10H6}PPh3] (6d) were also prepared. All compounds were characterised by NMR spectroscopies and 6c and 6d were also characterised crystallographically. For both [C,N,N′] and [C,N] systems, the metallation took place regioselectively at β-positions of the naphthyl group.