Chelating imidazole ligands promote oxidative addition in dimethylplatinum(II) complexes

The oxidative addition chemistry of the complexes [PtMe2{(mim)2CCH2}], 1, and [PtMe2{(mim)2CHMe}], 2, where mim = N-methylimidazol-2-yl, is described. Complex 1 undergoes oxidative addition with alkyl halides RX to give [PtXRMe2{(mim)2CCH2}], X = I, R = Me; X = Br, R = CH2Ph, CH2C6H4–4-CF3, CH2C6H4–2-CF3, CH2C6H3–3,5-t-Bu2; X = Cl, R = CH2Cl, and with hydrogen peroxide to give [Pt(OH)2Me2{(mim)2CCH2}]. Complex 2 undergoes oxidative addition with alkyl halides RX to give [PtXRMe2{(mim)2CHMe}], X = I, R = Me; X = Br, R = CH2C6H4–4-CF3, CH2C6H4–2-CF3, and with iodine and hydrogen peroxide to give [PtX2Me2{(mim)2CHMe}], X = I or OH. The stereochemistry of the reaction has been determined in each case, and several complexes have been structurally characterized. The high reactivity of complexes 1 and 2 towards oxidative addition is rationalized in terms of the strong donating property of the imidazolyl ligands, as supported by theoretical (DFT) studies.