Living polymerization of alpha-olefins with an alpha-diimine Ni(II) catalyst: formation of well-defined ethylene-propylene copolymers through controlled chain-walking.

A C2-symmetric Ni(II) catalyst was found to polymerize alpha-olefins with high levels of omega,2-regiochemistry. The resulting products are ethylene-propylene-type copolymers with methylene sequences of precise length between methyl branches. Modification of reaction conditions can introduce omega,1-enchainments into the polymers which increases the average length of methylene sequences between methyl branches.