Iron and Cobalt Complexes of 4-Alkyl-2,6-diiminopyridine Ligands: Synthesis and Ethylene Polymerization Catalysis

A new methodology for selective alkylation of the 2,6-diiminopyridine (pdi) ligands allows the ready synthesis of new derivatives displaying 2-methyl-2-phenylpropyl (neophyl), benzyl, or allyl groups in the 4-position of the pyridine ring. A set of Fe and Co complexes containing the new ligands have been synthesized and fully characterized. The presence of 4-neophyl or -benzyl groups does not perturb the performance of the complexes as ethylene polymerization catalysts, but the introduction of the 4-allyl group leads to the production of higher molecular weight polymers.