US Patent 6953764 High activity olefin polymerization catalyst and process

Group 4 metal complexes useful as addition polymerization catalysts of the formula:whereinG1 is a group containing from 1 to 40 atoms not counting hydrogen;T is a divalent bridging group of from 10 to 30 atoms not counting hydrogen, selected from mono- or di-aryl-substituted methylene or silylene groups or mono- or di-heteroaryl-substituted methylene or silylene groups, wherein at least one such aryl- or heteroaryl-substituent is substituted in one or both ortho-positions with a secondary or tertiary alkyl-group, a secondary or tertiary heteroalkyl group, a cycloalkyl group, or a heterocycloalkyl group,G2 is a C6-20 heteroaryl group containing Lewis base functionality,M is the Group 4 metal,X″″ is an anionic, neutral or dianionic ligand group,x″″ is a number from 0 to 5, andbonds, optional bonds and electron donative interactions are represented by lines, dotted lines and arrows respectively.