Useful Method for the Preparation of Low-Coordinate Nickel(I) Complexes via Transformations of the Ni(I) Bis(amido) Complex K{Ni[N(SiMe3)(2,6‑iPr2‑C6H3)]2}

2015-12-17T05:07:28Z (GMT) by Michael I. Lipschutz T. Don Tilley
A convenient method of preparing two- and three-coordinate Ni­(I) complexes of the form L–NiI–X (L = PtBu3, PiPr3, DPPE, NHC; X = −N­(SiMe3)­(2,6-iPr-C6H3), −O­(2,6-tBu2-4-Me-C6H2)) is reported. Protonation of the easily prepared anionic Ni­(I) bis­(amido) complex K­{Ni­[N­(SiMe3)­(2,6-iPr-C6H3)]2} in the presence of an appropriate L-type ligand results in loss of HN­(SiMe3)­(2,6-iPr-C6H3) and trapping of the resulting neutral Ni­(I)-amido fragment to yield neutral, paramagnetic, two- and three-coordinate Ni­(I) complexes. Protonation of these neutral amido complexes by the bulky phenol HO­(2,6-tBu2-4-Me-C6H2) results in loss of the second amido moiety and trapping by the resulting phenoxide to yield Ni­(I)-O­(2,6-tBu2-4-Me-C6H2) complexes. The hapticity of the phenoxide ligand is influenced by the π-accepting ability of the L-type ligand. Where L = PtBu3, a poor π-acceptor, the phenoxide acts as a π-acceptor and adopts a η5-bonding mode through dearomatization of the phenyl ring. When L = NHC, a competent π-acceptor, the phenoxide acts as a π-donor, adopting a η1-bonding mode through the O atom. The modular nature of this synthetic strategy allows variation of both the L- and X-type ligands of the complex in a stepwise fashion and should be extendable to a wide variety of ligand types for new Ni­(I) complexes.