Displacement of norbornadiene (NBD) from PtMe2(NBD) BY N-donors, dimethylsulfoxide, and cyanide, and reactions of cis-PtMe2L2 iodomethane

Norbornadiene (NBD) was displaced from PtMe2(NBD) by a range of ligands L to form cis-PtMe2L2 (L = pyridine (py), NH3, dimethylsulfoxide (DMSO); L2 = 2,2′-bipyridyl (bipy), ethylenediamine (en), N,N,N′,N′-tetramethylethylenediamine (tmen) - but not L = acetonitrile, benzonitrile, N, N-dimethylformamide, or water). These reactions occur more readily than the corresponding displacements of 1,5-cyclooctadiene (COD) from PtMe2(COD). Cyanide readily displaced the diolefin from either PtMe2(NBD) or PtMe2(COD) to form cis-PtMe2CN)2 2-, but no reaction occurred with bromide, chloride, and acetylacetonate. Thiocyanate and iodide slowly reacted, but no methyl-platinum product was obtained. The reaction of each of the compounds PtMe2L2 with MeI was studied in benzene. PtMe2(NBD) gave [PtMe3I]4. With L = py, 1 2(bipy), or 1 2(tmen), PtMe3IL2 was obtained rapidly at room temperature. For the sparingly soluble compounds with L = NH3 or 1 2(en), heating was necessary for reaction. The product from PtMe2(en) was PtMe3I(en), but cis-PtMe2(NH3)2 gave a mixture of [PtMe3(NH3)(μ-I)]2 and fac-[PtMe3(NH3)3]I. With L = DMSO, heating initially gave PtMe3I(DMSO)2, which slowly lost DMSO to form [PtMe3I]4. For L = py, 1 2(tmen), treatment with acid readily removed L from PtMe3IL2