title: Half-sandwich nickel complexes with ring-expanded NHC ligands - synthesis, structure and catalytic activity in Kumada-Tamao-Corriu coupling.
abstract: The general synthesis of [Ni(Cp)(X)(NHC)] complexes from a nickel halide, CpLi, and a carbene solution is reported. This procedure yields unprecedented complexes with ring-expanded NHC ligands (RE-NHC) of six- (1a, 1b), seven- (1c), and eight-membered (1d) heterocycles. The NMR spectra of 1a-1d are consistent with the hindered rotation of Ni-Ccarbene and N-CMes bonds, while X-ray analyses of 1b, 1c, and 1d reveal a pronounced trans influence of the RE-NHC ligands. Complexes 1a-1e are efficient pre-catalysts in Kumada-Tamao-Corriu coupling with the maximum efficiency observed for complexes bearing the six-membered NHC.
authors: Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland. wbuch@ch.pw.edu.pl.
authors: Ł
authors: Ł
authors: Banach
authors: P A
authors: PA
authors: Guńka
authors: W
authors: W
authors: Buchowicz