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.