The Chemistry of [PtMe2(1,2-bis(2-pyridyl)ethane)]: Remarkable Impact of an Easily Dissociated Chelate Ligand

The title compound [PtMe2(bpe)], 1, bpe = 1,2-bis(2-pyridyl)ethane, is easily oxidized to give octahedral organoplatinum(IV) complexes, and the subsequent chemistry is profoundly influenced by the accompanying strain induced in the seven-membered Pt(bpe) chelate ring. In reactions with bromine or iodine, X2, the platinum(IV) complexes [PtX2Me2(bpe)] are formed initially, but they decompose primarily by reductive elimination of MeX to give ultimately the platinum(II) complexes [PtX2(bpe)]. When X = I, a minor reaction occurred to give the first example of metalation of a CH2 group of the bpe ligand. On reaction of 1 with HCl, the initial product [PtHClMe2(bpe)] undergoes reductive elimination of methane to form [PtClMe(bpe)]. In contrast, methyl iodide reacts with 1 to give [PtIMe3(bpe)], and this decomposes by loss of the bpe ligand to give the cubane [(PtIMe3)4] and not by reductive elimination. Finally, a new class of platinum(IV) double cubane clusters was obtained on oxidation of complex 1 either with hydrogen peroxide to give [Pt4(μ-OH)4(μ3-OH)2Me10], as a mixed complex with [PtMe2(CO3)(bpe)], or with oxygen in methanol to give [Pt4(μ-OH)2(μ-OMe)2(μ3-OMe)2Me10].