Octahedral group IV bis(phenolate) catalysts are highly active catalysts for the isospecific polymerization of 1-hexene and the copolymerization of ethylene with 1-hexene. These catalysts are active for the production of high molecular weight copolymers even at 130 degrees C. The copolymerization parameters for these complexes were determined; all of the bis(phenolate) complexes tested incorporate 1-hexene with high efficiency to give random copolymers. The complexes prepared from the more sterically demanding ligands showed higher molecular weights but similar comonomer incorporations to those prepared from the less sterically demanding ligands.