Mechanistic studies of catalytic polyethylene chain growth in the presence of water.

General procedures and materials All 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 CH2Cl2 over CaH2. The deuterated solvents [D8] THF, CD2Cl2 and CDCl3 were purchased from Eurisotop, dried and vacuum– transfered prior to use. CD2Cl2 and CDCl3 were distilled from CaH2, [D8] THF from a NaK– alloy. Ethylene (99.95%) supplied by Praxair was used as received. H NMR experiments were performed on a Varian 400 spectrometer. Chemical shifts were referenced 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. 1D H spectra of α–diimine(dimethyl)palladium(II) were acquired at room temperature on a Bruker 250 spectrometer operating at 250 MHz.