Base-Free Phosphine−Sulfonate Nickel Benzyl Complexes

Base-free 2-PR 2 -4-Me-benzenesulfonate)Ni(η 3 -benzyl) complexes (R = 2-OMe-Ph ( 4a ), Cy ( 4b )) were prepared and tested for ethylene polymerization. 4a produces low-molecular-weight polyethylene ( M n = 1300) that contains 10 Me branches/10 3 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 M n, fewer branches, and a higher fraction of terminal olefin units.