| abstract |
The present invention provides a catalyst precursor compound and catalyst composition form making polyolefins, an embodiment of the precursor is selected from the following structures: wherein T is a bridging group; M is selected from Groups 3 to 7 and the Lanthanide series of the Periodic Table of the Elements; Z is a coordination ligand; each L is a monovalent, bivalent, or trivalent anionic ligand; X is oxygen or sulfur; X and Y are each independently selected from nitrogen, phosphorus, oxygen or sulfur; R is a non-bulky substituent that has relatively low steric hindrance with respect to the X substituent; and R' is a bulky substituent with respect to Y and is selected from alkyl, alkenyl, cycloalkyl, heterocyclic (both heteroalkyl and heteroaryl), alkylaryl, arylalkyl, and polymeric groups. Other groups are as defined in the specification and claims. |