Mechanistische Untersuchungen des Kettenwachstums von Polyethylen in Gegenwart von Wasser

Abstract

General procedures and materialsAll experiments were carried out under argon of 99.998 % purity using standard Schlenk line techniques or in a glovebox under nitrogen. All glassware was dried carefully by treatment with a heat gun under high vacuum or in an oven at 90• C overnight. Solvents were dried and distilled under argon prior use. Ethers were dried over Na/ benzophenone, pentane and CH 2 Cl 2 over CaH 2 . to residual proton resonances of the solvents. In general, low temperature NMR experiments were carried out with prior temperature determination using a sample of neat methanol. 1D1 H spectra of α-diimine(dimethyl)palladium(II) were acquired at room temperature on a Bruker 250 spectrometer operating at 250 MHz. Synthetic ProceduresThe Synthesis of α-diimine(dimethyl)palladium(II)A 100 mL Schlenk flask was charged with 0.57 g (2 mmol) of [(cod)PdCl 2 ] and 0.11 g (2 mmol) of dimethyl magnesium in the glovebox. After cooling to -80• C, 40 mL of diethyl ether were added via canula. The resulting yellow suspension was stirred and allowed to warm to -30• C. After filtration and washing of the residual solid with diethyl ether at -10• C the resulting light brown solution was cooled again to -80• C. Afterwards, a solution of 0.81 g (2 mmol) of the diimine in 10 mL of diethyl ether was added via canula. After warming to room temperature overnight a brown solid precipitated. The suspension was chilled again to -30• C in order to complete precipitation. The resulting red brown solid was isolated and washed with a small amount of pentane. Finally, it was dissolved in 10 mL of methylene chloride. The solvent was reduced to approximately 2 to 3 mL and the deep red solution was layered with 20 mL of pentane. Crystallisation at room temperature yielded 0.52 g (0.96 mmol, 48%) of dark purple crystals.