The reactivity of pyridine-imine and diamine ligands with dimethylplatinum(II) compounds

The reactions of [Pt(2)Me(4)(mu-SMe(2))(2)] (1) with pyridine-imines 2-(CH = NCHRR')C5H4N [R = H, R' = 2-BrC6H4 (2a); R = H, R' = 2,4-Cl2C6H3 (2b); R = Me, R' = C6H5 (2c)] or diamines Me(2)N(CH2)(2)N(Me)CH(2)R [R = 2-BrC6H4 (5d); R = C6F5 (5e); R = C6H5 (5f)] result in the formation of complexes [PtMe(2){2-(CH = NCHRR')C5H4N}] (3) and [PtMe(2){Me(2)N(CH2)(2)N(Me)CH(2)R}] (6), respectively, in which the ligand is coordinated through the two nitrogen atoms to platinum, but such reactions fail to produce metallation at the benzyl group. The reactivity of the more flexible diamines Me(2)N(CH2)(3)N(Me)CH(2)R [R = 2-BrC6H4 (5g); R = C6F5 (5h); R = C6H5 (5i)] was also tested in the presence of [Pt(2)Me(4)(mu-SMe(2))(2)] (1). While 5h and 5i failed to react, activation of a C-Br bond to produce the platinum(IV) compound [PtMe(2)Br{Me(2)N(CH2)(3)N(Me)CH2C6H4}] (7g), which contains a terdentate (C,N,N') ligand, was achieved with 5g. Compounds 3 reacted readily with methyl iodide to afford platinum(IV) compounds[PtMeI2-(CH=NCHRR')C5H4] (4).