2016 Volume 67 Pages 19-29
Cationic bis(imino)pyridine iron alkene complexes, key intermediates in the polymerization and oligomerization of ethylene, have been targeted to understand important physical properties such as spin state of the metal and the role of the redox-active supporting ligand. The allyl derivative, (MePDI)Fe(h3-C3H5) was synthesized but proved unstable toward one electron oxidation with ferrocenium reagents. Tethered alkoxide-alkene complexes were explored as more well behaved alternatives and (MePDI) Fe(OC(Ph)2CH2(h2-CHCH2) was synthesized, crystallographically characterized and determined to be a high spin Fe(II) complex with a bis(imino)pyridine radical anion. One electron oxidation with [Cp2Fe][BArF24] (BArF24 = C6H3-3,5-(CF3)2) generated the desired cationic iron complex, [(MePDI)Fe(OC(Ph)2(h2-C3H5))][BArF24]. The solid-state structure confi rmed alkene coordination and provided the metrical parameters used to establish a neutral bis(imino)pyridine chelate. The observation of a high spin Fe(II) complex demonstrates that the iron does not change spin state upon olefi n coordination.