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

Comprehensive SummaryNickel(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 1H 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 Et2AlCl or Et3Al2Cl3 are active both in ethylene oligomerization and Friedel‐Crafts alkylation processes (activity up to 3720 kgoligomer·mol[Ni]−1·h−1). The use of Et3Al2Cl3 results in a higher share of alkylated products (up to 60%). Moreover, catalytic systems activated with Et3Al2Cl3 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 (C3 and C5).