Synthesis, crystal structures and use in ethylene oligomerization catalysis of novel mono- and dinuclear nickel complexes supported by (E)-N′-(1-(thiophen-2-yl)ethylidene)benzohydrazide ligand

The coordination chemistry of NiII supported by (E)-N′-(1-(thiophen-2-yl)ethylidene)benzohydrazide ligand (HL) is reported and discussed. The crystal structure of ligand HL has been determined as well as those of three new NiII complexes (Ni(HL)2Br2, NiL2 and μ-aquo-Ni2L4). The pseudo-octahedral bis(chelate) Ni(II) complex 2 (NiL2), in which unexpected and singular Ni⋯S interaction is observed, was evaluated as catalyst for the oligomerization of ethylene and found to provide ethylene dimers and trimers as primary products with a turnover frequency (TOF) of 31 200 mol of C2H4 per mol. of Ni and per hour.