om8b00333_si_001.pdf (1.34 MB)
Synthesis, Characterization, and Reactivity of PCN Pincer Nickel Complexes
journal contribution
posted on 2018-07-18, 18:47 authored by Abdelrazek
H. Mousa, Jesper Bendix, Ola F. WendtNew diamagnetic nickel(II) complexes
based on an unsymmetrical
(1-(3-((ditert-butylphosphino)methyl)phenyl)-N,N-dimethyl-methanamine) (PCN) pincer
ligand were synthesized and characterized by 1H, 31P{1H}, and 13C{1H} NMR spectroscopy.
Their molecular structures were confirmed by X-ray diffraction. Oxidation
to high-valent paramagnetic Ni(III) dihalide complexes was achieved
through straightforward reaction of the corresponding diamagnetic
halide complexes with anhydrous CuX2 (X = Cl, Br). In agreement
with this, the complexes are active in Kharasch addition of CCl4 to olefins. The reaction of the hydroxo complex (8) and the amido complex (11) with CO2 produced
the hydrogen carbonate and carbamate complexes, respectively. The
hydrogen carbonate complex was converted to the dinuclear nickel carbonate
complex (10). The methyl (13), phenyl (14), and p-tolylacetylide (15) complexes are also described in the current study providing the
first example of the hydrocarbyl nickel complexes based on an unsymmetric
aromatic pincer ligand. Furthermore, the reactivity of the methyl
complex toward different electrophiles has been investigated, showing
that C–C bond formation is possible with aryl halides, whereas
the reaction with CO2 is sluggish.