Polymerization of isoprene catalyzed by high active and thermo-stable iminopyridine-titanium complexes

A series of well-defined iminopyridine-titanium complexes were prepared and characterized by nuclear magnetic resonance spectroscopy, X-ray diffraction analysis and elemental analysis. Isoprene polymerization was carried out by using those complexes as main catalyst and dried methylaluminoxane as cocatalyst.The results showed that the iminopyridine-titanium complexes with strong electron-donating group possessed high activity （up to 6.3×104 g/（mol·h））, high cis-1,4 -unit selectivity (up to 74%) and excellent thermo-stability（up to 90 ℃）. The increased steric hindrance of substituent groups would significantly reduce the catalytic acti-vity, molecular weight and cis-1,4-unit selectivity. These results indicated that the ligand structure had more effects on activity than stereo-selectivity.