Isoprene polymerization catalyzed by iron (II) and cobalt(II) complexes carrying 2,6‐bis(1H′‐allylbenzimidazolyl)pyridyl ligand.

The incorporation of cis‐1,4 and 3,4(+1,2) units is important to the overall properties of polyisoprene. Nevertheless, polymerization to prepare such polymer via coordinative‐insertion method has less reported. In the present study, 2,6‐bis(1H'‐allyl‐benzimidazolyl)pyridine has been installed onto the iron and cobalt prior to heterogeneous supporting. They are shown to be amenable to homogeneous polymerization of isoprene, affording 3,4(+1,2) units enriched polymer. The addition of disulfide carbon into cobalt catalyst is decisive for boosting productivity and elevating 3,4 (+1,2) insertion. Whereas, diethylphosphite external donor merely behaves as a chain transfer agent in iron catalyzed polymerization. The produced polymer with a controlled 3,4(+1,2) ratio and molar mass may find application as a single rubber, in polymer blends, composites, adhesives, and as a versatile platform for transforming to a wide range of functional polymer. Highlights: Novel iron and cobalt complexes are made.High activities toward isoprene polymerization are achieved.3,4(+1,2) incorporated polyisoprene is obtained. [ABSTRACT FROM AUTHOR]