Molecular structure, magnetic properties and catalytic activity in selective ethylene dimerization of nickel (II) complexes with bis(3,5-dimethylpyrazol-1-yl)methane

• Published in: Journal of molecular structure Vol. 1206; p. 127692
• Main Authors: Zubkevich, Sergey V., Tuskaev, Vladislav A., Gagieva, Svetlana Ch, Pavlov, Alexander A., Khrustalev, Viktor N., Zarubin, Dmitriy N., Kurmaev, Dmitriy A., Kolosov, Nikolai A., Bulychev, Boris M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.04.2020
• Subjects: Bispyrazolylmethane; Ethylene; Nickel; Nickel complexes; Oligomerization; Nickel complexes; Nickel; Oligomerization; Bispyrazolylmethane; Ethylene
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2020.127692

Nickel(II) complexes with neutral bidentate nitrogen-containing ligands are of great interest as promising precatalysts for the selective oligomerization of ethylene. Complexes of compositions 0.75[LNiCl2]2•0.25[LNiClBr]22 and LNiBr23 where L = bis-(3,5-dimethylpyrazol-1-yl)methane have been synthesized and characterized by single crystal X-ray diffraction, IR and 1H NMR spectroscopies and elemental analysis. The 1H NMR spectra of paramagnetic complexes indicate that the structures of these complexes in solution are similar to ones in the solid state. Magnetic susceptibility of the compounds has been investigated and discussed in the context of their structures. Treatment of these complexes with diethylaluminum chloride (DEAC) or ethylaluminum sesquichloride (EASC) generates active catalysts that oligomerize ethylene to yield mostly butenes with activities up to 930 kg(oligomers)·mol[Ni]−1·h−1 (DEAC). [Display omitted] •Two Ni (II) complexes with bis(3,5-dimethylpyrazol-1-yl)methane were synthesized.•Their structures have been determined by X-Ray in crystal and by 1H NMR in solution.•Ni (II) complexes activated with Et2AlCl or Et3Al2Cl3 selectively dimerize ethylene.•The selectivity towards 1-butene was up to 90.5 mol. %.•The maximum of catalytic activity reached 930 kg mol[Ni]−1·h−1.