Ligand-regulated polymerization of conjugated dienes catalyzed by confined iminopyridine iron complexes with high activity and thermal stability
Guangqian Zhu, Liang Wang, Qaiser Mahmood, Li Zhou, Qinggang Wang
Abstract
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 108 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 °C within 10 min. Surprisingly, the polymerization activities of bio-based monomer β-farnesene and β-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.