A β-Diketiminato-Based Pincer-Type Nickel(II) Complex: Synthesis and Catalytic Performance in the Cross-Coupling of Aryl Fluorides with Aryl Grignard Reagents

A beta-diketiminato-based tridentate pincer-type nickel(II) complex Ni-NNP was prepared by the reaction of the nickel(II) precursor [NiCl2(2,4-lutidine)(2)] with the lithiated NNP ligand, which was generated in situ by the reaction of the NNP pro-ligand H-NNP with nBuLi. H-NNP was prepared by the condensation of 4-[(2,4,6-trimethylphenyl)amino]pent-3-en-2-one with 2-(diphenylphosphanyl)ethylamine. Ni-NNP was characterized spectroscopically and by X-ray diffraction, revealing a slightly distorted square-planar geometry around the nickel center. Density functional theory calculations indicated that the highest occupied molecular orbital in Ni-NNP is located at higher energy than those of three other homologous nickel(II) complexes, i.e., Ni-ONN, Ni-ONP, and Ni-NNN, which contain beta-aminoketonato- or beta-diketiminato-based pincer-type ligands. The electronic and steric properties of Ni-NNP effectively facilitated the cross-coupling of aryl fluorides with aryl Grignard reagents.