Ligand-regulated polymerization of conjugated dienes catalyzed by confined iminopyridine iron complexes with high activity and thermal stability

A range of confined iminopyridine iron complexes with skeleton of 8-(arylimino)-5,6,7-trihydroquinolyl have been prepared and well characterized by HRMS spectroscopy, FT-IR spectroscopy as well as elemental analysis. These iron complexes (Fe1-Fe5) serve as highly efficient pre-catalysts for conjugated dienes polymerization. By adjusting substituents of ligand framework, the stereoselectivity about 1,4-cis/trans could be switched from <1/99 to 96/4. An outstanding polymerization activity up to 10(8) g mol(-1) h(-1) was achieved with high molecular weight by employing Fe1 as pre-catalyst under optimum experimental conditions. What's more, the Fe1/MAO catalytic system showed excellent thermostability, which could lead to full conversion even at 100 degrees C within 10 min. Surprisingly, the polymerization activities of bio-based monomer beta-farnesene and beta-myrcene were able to reach 106 g mol(-1) h(-1) by Fe-1/MAO catalytic system, which was the highest activity of iron complex family to deliver the green rubbers with high molecular weights.

Automated summary

Confined iminopyridine iron complexes with skeleton of 8-(arylimino)-5,6,7-trihydroquinolyl were synthesized and characterized, serving as highly efficient pre-catalysts for conjugated dienes polymerization. Adjusting substituents of ligand framework allowed for control of stereoselectivity, achieving high activity and molecular weight in polymerization reactions. The Fe1/MAO catalytic system showed excellent thermostability and high activity in polymerizing bio-based monomers, delivering green rubber with high molecular weights.