Base-Free Phosphine−Sulfonate Nickel Benzyl Complexes

Base-free [2-PR2-4-Me-benzenesulfonate)]Ni(η3-benzyl) complexes (R = 2-OMe-Ph (4a), Cy (4b)) were prepared and tested for ethylene polymerization. 4a produces low-molecular-weight polyethylene (Mn = 1300) that contains 10 Me branches/103 C and terminal and internal olefin units. The polymer yield and structure are unaffected by the ethylene pressure (60−300 psi). 4b is less active than 4a and produces a polymer with higher Mn, fewer branches, and a higher fraction of terminal olefin units.