Evidence of coordinative chain transfer polymerization of isoprene using iron iminopyridine/ZnEt₂ catalytic systems

Isoprene polymerization using iminopyridine-supported iron complexes combined with AlⁱBu₃/[B(C₆F₅)₄][CPh₃] was carried out in the presence of ZnEt₂ as the chain transfer agent (CTA). Detailed studies revealed that the M_n of the resulting polyisoprenes and the rate of polymerization decrease steadily as the amount of CTA increases while preserving the catalyst selectivity. These results highlight the first example of a reversible iron-mediated chain transfer polymerization of isoprene.