CATIONIC METHYL(HYDRIDO)PLATINUM(IV) COMPLEXES

The new complex [PtMe2(BPMA)], 1, BPMA = bis(2-pyridylmethyl)amine, is shown to contain bidentate BPMA with one of the pyridyl groups not co ordinated to platinum. Complex 1 reacts with HX (X = Cl, BF4) at ro om temperature to yield [PtHMe2(BPMA)][X], which may exist in two isomer ic forms, each containing tridentate BPMA. The major initial product 2 has the hydride trans to a pyridyl group, but this equilibrates with isomer 3 in which the hydride is trans to an amine. The cationic methy l(hydrido)platinum( TV) complexes 2 and 3 are stable at room temperatu re for several hours, but undergo slow reductive elimination of CH4 to yield [PtMe(BPMA)][X], 4. Complex 1 reacts with DCl to give [PtDMe2(B PMA)][X], and deuterium incorporation at the methyl group traits to am ine occurs slowly; the methane formed by subsequent reductive eliminat ion is a mixture of CH4, CH3D, and CH2D2. Reaction of 1 with Mel initi ally yields a mixture of two compounds, [PtMe3(BPMA)][I], 5a, and a ne utral compound, [PtIMe3(BPMA)], 6, but 6 isomerizes to 5 over a period of 2 h at room temperature. Reaction of 1 with CD3I gives [PtMe2(CD3) (BPMA)][I], 5a, and [PtIMe2(CD3)(BPMA)], 6*, with CD3 largely trans t o pyridyl or iodide, respectively, but equilibration gives a mixture o f 5a and 5a**, in which CD3 is trans to amine. In contrast to the rea ction with MeI, oxidative addition of CF3SO3Me to 1 gives only [PtMe3( BPMA)][CF3SO3], 5b. Reaction of 1 with allyl bromide yields a mixture of two products, [PtMe2(CH2CH=CH2)(BPMA)][Br], 7, and [PtBrMe2(CH2CH=C H2)(BPMA)], 8; complex 8 isomerizes rapidly to 7. Complexes 4 and 7 ha ve been characterized by X-ray structure determinations and are shown to contain the BPMA ligands in fac and mer coordination modes.