Synthesis, characterization, and ethylene polymerization behaviors of late-transition metal complexes coordinated with chlorinated bis(arylimino)pyridine ligand

A series of late-transition metal complexes supported with chlorinated bis(arylimino)pyridine ligands [2,6-(ArNCCl)₂C₅H ₃N]MtCl₂ (Ar = 2,4,6-Me₃C₆H ₂, Mt = Fe (1a), Co (2a), Ni (3a); Ar = 2,6-ⁱPr ₂C₆H₃, Mt = Fe (1b), Co (2b); Ar = 2,6-Et ₂C₆H₃, Mt = Co (1c), Ni (3c); Ar = 2,6-Me ₂C₆H₃, Mt = Fe (1d), Co (2d); Ar = 4-Cl-2,6-Me₂C₆H₂, Mt = Fe (1e), Co (2e); Ar = 4-Br-2,6-Me₂C₆H₂, Mt = Fe (1f), Co (2f)) were synthesized. At the presence of methylaluminoxane (MAO), Fe(II)- and Co(II)- based complexes were highly active towards ethylene polymerization, affording polymers with bimodal and unimodal molar mass distributions, respectively, while the Ni(II)-based complexes gave no polymer products. Moreover, the obtained polyethylenes were predominately saturated and vinyl-terminated for Fe(II)- and Co(II)-based complexes, respectively. Changing the ligand environment, polymerization parameters also posed a great influence on the catalytic activities and the properties of the resulting polymers.