Synthesis and Reactivity of Two-Coordinate Ni(I) Alkyl and Aryl Complexes

Reaction
of [(IPr)­Ni­(μ-Cl)]2 (1-Cl; IPr = 1,3-bis­(2,6-diisopropylphenyl)­imidazolin-2-ylidene)
with
ClMg­{CH­(SiMe3)2}·Et2O affords
(IPr)­Ni­{CH­(SiMe3)2} (2), a two-coordinate
Ni­(I) alkyl complex. An analogous two-coordinate aryl derivative,
(IPr)­Ni­(dmp) (dmp = 2,6-dimesitylphenyl), can be similarly prepared
from Li­(dmp) and 1-Cl. Reaction of 2 with
alkyl bromides gives the three-coordinate Ni­(II) alkyl halide complex
(IPr)­Ni­{CH­(SiMe3)2}­Br. Evidence for a radical
mechanism is presented to explain the reaction of 2 with
alkyl halides.