UC Berkeley

A convenient method of preparing two- and three-coordinate Ni(I) complexes of the form L-Ni^I-X (L = P ^t Bu₃, P ⁱ Pr₃, DPPE, NHC; X = -N(SiMe₃)(2,6- ⁱ Pr-C₆H₃), -O(2,6- ^t Bu₂-4-Me-C₆H₂)) is reported. Protonation of the easily prepared anionic Ni(I) bis(amido) complex K{Ni[N(SiMe₃)(2,6- ⁱ Pr-C₆H₃)]₂} in the presence of an appropriate L-type ligand results in loss of HN(SiMe₃)(2,6- ⁱ Pr-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- ^t Bu₂-4-Me-C₆H₂) results in loss of the second amido moiety and trapping by the resulting phenoxide to yield Ni(I)-O(2,6- ^t Bu₂-4-Me-C₆H₂) complexes. The hapticity of the phenoxide ligand is influenced by the π-accepting ability of the L-type ligand. Where L = P ^t Bu₃, 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.