Coordination of a Diphosphine–Ketone Ligand to Ni(0), Ni(I), and Ni(II): Reduction-Induced Coordination

The coordination chemistry of the diphosphine–ketone ligand 2,2′-bis­(diphenylphosphino)­benzophenone (Phdpbp) with nickel is reported. The ketone moiety does not bind to Ni­(II) in the complex (Phdpbp)­NiCl2, whereas reduction to Ni­(I) or Ni(0) induces η2(C,O) coordination of the ketone to form the pseudotetrahedral complexes (Phdpbp)­NiCl and (Phdpbp)­Ni­(PPh3). DFT calculations indicate that the metal–ketone bond is dominated by π back-donation; hence, Phdpbp functions as a hemilabile acceptor ligand in this series of complexes.