132 PI catalysts: New titanium complexes having two pyrrolide-imine chelate ligands for olefin polymerization

Abstract

Publisher Summary This chapter introduces new titanium complexes bearing two pyrrolide–imine chelate ligands, named PI Catalysts. New bis(pyrrolyl-2-aldiminato) titanium complexes, named PI Catalysts, were prepared from the lithium salt of the corresponding ligands and TiCl 4 , and their molecular structures were established by X-ray analyses. Prototype PI Catalyst adopts a distorted octahedral geometry around the Ti center, thus, the two pyrrole nitrogen atoms are situated in trans position, while the two imine nitrogen and the two chlorine atoms are oriented cis to each other at the central titanium. The results of DFT calculations on a methyl cationic complex, an initial active species formed by methylalumoxane (MAO) for olefin polymerization, indicate that the cationic complex has cis -located active sites. These results together with X-ray analysis suggest that a complex has a high potential for olefin polymerization. PI Catalysts displayed high ethylene polymerization activities using MAO as a cocatalyst. The activity increased dramatically by introducing a bulky X substituent. One of the complexes exhibited a very high activity with a very high molecular weight value.