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.本文报道了一种搭载同官能双齿配体的八面体过渡金属配合物[(dppa)­Fe­(Ph₂P–N–PPh₂)₂]（化合物1），其中dppa为双(二苯基膦基)胺（bis(diphenylphosphino)amine）。该配体因自身较小的咬角以及配位给体基团间的空间位阻而表现出半配位性（hemilability）。由于{Ph₂P–N–PPh₂}⁻配体可作为内碱，配合物1对氢气的异裂可生成氢化物配合物[(dppa)­(Ph₂P–N–PPh₂)­Fe­(H)­(κ¹-Ph₂P–NH–PPh₂)₂]（化合物2），该体系为利用同官能半配位配体实现协同键活化的典型案例。本研究证实，通过精细调控几何参数，可改变同官能化配体的半配位性。