The reactions of 2,6-bis(3,5-dimethylpyrazol-1-ylmethyl)pyridine (L1) and 2,6-bis(3,5-di-tert-butylpyrazol-1-ylmethyl)pyridine (L2) with NiCl 2 or NiBr 2 gave the nickel(II) complexes [NiCl 2 (L1)] (1), [NiBr 2 (L1)] (2), [NiCl 2 (L2)] (3), and [NiBr 2 (L2)] (4) in high yields. Compounds 2-(3,5-dimethylpyrazol-1-ylmethyl)pyridine (L3) and 2-(3,5-di-tert-butylpyrazol-1-ylmethyl)pyridine (L4) on the other hand gave either mononuclear or dinuclear nickel(II) complexes, depending on the steric bulk of the substituents on the pyrazolyl unit. While L3 gave the dinuclear complexes [Ni 2 (µ 2 -Cl) 2 Cl 2 (L3) 2 ] (5) and [Ni 2 (µ 2 -Br) 2 Br 2 (L3) 2 ] (6), L4 gave the mononuclear complexes [NiCl 2 (L4)] ( 7) and [NiBr 2 (L4)] ( 8). Activation of 1-8 with EtAlCl 2 resulted in the oligomerization of ethylene to C 4 , C 6 , and C 8 alkenes, followed by subsequent Friedel-Crafts alkylation of the toluene solvent. Activities as high as 15 660 kg of alkylated products/mol Ni/h were observed for 5 at 40 bar. However, when hexane was used as solvent, only trace amounts of alkylated toluene products were observed.

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