In this work, three different types of acetylacetonato-based pincer-type nickel(ii) complexes (2) were prepared. Complex 2a possessed the tridentate ONN ligand, which was constructed by the condensation reaction of acetylacetone with N,N-diethylethylenediamine. Complex 2b contained the PPh2 donor group in contrast to the NEt2 group in 2a, i.e., an ONP ligand framework. Complex 2c was composed of the NNN ligand, which was prepared by the reaction of 4-((2,4,6-trimethylphenyl)amino)pent-3-en-2-one with N,N-diethylethylenediamine. In addition to X-ray diffraction analysis, these complexes were characterized spectroscopically. Their catalytic activity for a cross-coupling reaction of aryl halides with aryl Grignard reagents was also evaluated. Among these complexes, 2b acted as an effective catalyst for the cross-coupling reaction using aryl chlorides as electrophiles. The electronic properties of these Ni(ii) complexes were investigated by cyclic voltammetry and density functional theory calculations.

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A β‐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 β‐aminoketonato‐ or β‐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.