Switchable Synthesis of Ethylene/Acrylate Copolymers by a Dinickel Catalyst: Evidence for Chain Growth on Both Nickel Centers and Concepts of Cation Exchange Polymerization

A dinickel complex, X-Ni₂, was developed and demonstrated to have a high performance in ethylene/acrylate copolymerization. Further mechanistic studies revealed that X-Ni₂ performs acrylate insertion at both Ni centers at distinct rates. Addition of NaBAr^F₂₄ to X-Ni₂ leads to 1:1 binding and serves as a switch for tuning catalytic activity, copolymer MW and acrylate incorporation. NMR studies of cation binding, when present in substoichiometric amounts, suggest a dynamic process involving cation exchange. This phenomenon provides an alternative strategy for controlling chain growth in polar polyolefin synthesis and was probed herein.