Trapping the Short‐Chain Odd Carbon Number Olefins Using Nickel(II)‐Catalyzed Tandem Ethylene Oligomerization and Friedel‐Crafts Alkylation of Toluene

Comprehensive Summary Nickel(II) complexes with pyrazole‐based ligands are widely employed in catalysis of ethylene oligomerization and subsequent Friedel‐Crafts alkylation of toluene. We have prepared ten new nickel(II) dibromide complexes with various substituted bis(azolyl)methanes. They have been characterized using 1 H NMR, IR, high resolution mass spectrometry and elemental analysis. The structures of three complexes have been unambiguously established using X‐ray diffraction. It was found that these complexes in the presence of Et 2 AlCl or Et 3 Al 2 Cl 3 are active both in ethylene oligomerization and Friedel‐Crafts alkylation processes (activity up to 3720 kg oligomer ·mol[Ni] −1 ·h −1 ). The use of Et 3 Al 2 Cl 3 results in a higher share of alkylated products (up to 60%). Moreover, catalytic systems activated with Et 3 Al 2 Cl 3 produced small amounts of odd carbon number olefins (up to 0.8%). The Friedel‐Crafts alkylation was used as a trap for previously undetected short‐chain odd carbon number olefins (C 3 and C 5 ).