Ethylene oligomerization, homopolymerization and copolymerization by iron and cobalt catalysts with 2,6-(bis-organylimino)pyridyl ligands

In this review are highlighted the key advances that have occurred in the discovery and development of 2,6-bis(imino)pyridyl iron(II) and cobalt(II) catalysts for the transformation of ethylene into linear and branched homopolymers or into α-olefins with either Schulz–Flory or Poisson distribution. Particular attention has been paid to studies of the electronic and geometrical structure of both supporting ligands and metal complexes as well as to the mechanisms of precatalyst activation, chain-propagation and chain-transfer.