Metal–Ligand Cooperation in H₂ Activation with Iron Complexes Bearing Hemilabile Bis(diphenylphosphino)amine Ligands

The octahedral transition-metal complex [(dppa)­Fe­(Ph2P–N–PPh2)2] (1) [dppa = bis­(diphenylphosphino)­amine] with homofunctional bidentate ligands is described. The ligand exhibits hemilability due to its small bite angle and the steric repulsion of the coordinated donor groups. As the {Ph2P–N–PPh2}− ligand can act as an internal base, heterolytic cleavage of dihydrogen by complex 1 leads to the formation of the hydride complex [(dppa)­(Ph2P–N–PPh2)­Fe­(H)­(κ1-Ph2P–NH–PPh2)2] (2), representing an example of cooperative bond activation with a homofunctional hemilabile ligand. This study demonstrates that hemilability of homofunctionalized ligands can be affected by careful adjustment of geometric parameters.