Diiminopyridine

The three nitrogen centres bind metals in a tridentate fashion, forming pincer complexes.

Complexes of DIPs participate in a range of chemical reactions, including ethylene polymerization, hydrosilylation, and hydrogenation.

[4] The highly conjugated ligand framework of bis(imino)pyridine stabilizes metals in unusual oxidation states.

The ability of the neutral complex to accept up to three electrons leads to ambiguity about the oxidation states of the metal center.

[5] This assignment is corroborated by the high frequency of the νNN vibration in the infrared spectrum, which is more consistent with Fe(II).

Activities for 2,6-bis(imino)pyridine iron complexes are often comparable to or greater than group 4 metallocenes.

Reactions proceed under mild conditions, show anti-Markovnikov selectivity, and tolerate diverse functional groups.

[10] Depending on the steric properties of the ligand, Fe-DIP complexes catalyze hydrogenation of terminal olefins.

[1] In N-heterocyclic carbene variations of the diiminopyridine complex, the pyridine or imine substituents is replaced with an NHC group.