| abstract |
The present invention provides catalyst precursor compounds and catalyst compositions for the production of polyolefins. Specific examples of the precursor are selected from the following structures. [Chemical 1] Where T is a bridging group; M is selected from groups 3-7 of the periodic table and the lanthanide group; Z is a coordination ligand; each L is monovalent, divalent or trivalent anionic X is oxygen or sulfur; X and Y are each independently selected from nitrogen, phosphorus, oxygen or sulfur; R is a non-bulky substituent with relatively low steric hindrance to the X substituent; R ′ is a bulky substituent for Y and is selected from alkyl, alkenyl, cycloalkyl, heterocycle (both heteroalkyl and heteroaryl), alkylaryl, arylalkyl and polymeric groups. Other groups are as defined in the specification and claims. |