EPR spectroscopy of catalytic systems based on nickel complexes of 1,4-diaza-1,3-butadiene (α-diimine) ligands in hydrogenation and polymerization reactions
Yu.Yu. Titova1, L.B. Belykh2, and F.K. Schmidt2
1Иркутский государственный университет, Институт нефте- и углехимического синтеза, ул. К. Маркса, 1, г. Иркутск, 664030, Россия
2Иркутский государственный университет, химический факультет, ул. К. Маркса, 1, г. Иркутск, 664030, Россия pos Анотація:
Received August 18, 2014
The catalytic systems based on α-diimine complexes of Ni(0) and Ni(II) of the general formulas NiBr2(DAD–R) (R = –C3H7 or –CH3) and Ni(DAD–CH3)2 (DAD(–C3H7) = 1,4-bis(2,6-diisopropylphenyl)-2,3-(dimethyl-1,4-diazabuta-1,3-diene, DAD(–CH3) = 1,4-bis 2,6-dimethylphenyl)-2,3-dimethyl-1,4-diazabuta-1,3-diene), with Lewis acids (AlEt3, AlEt2Cl, AlEtCl2, B(F5C6)3, BF3·OEt2) in hydrogenation and polymerization reactions were investigated by the EPR spectroscopy method. The Ni(I) complexes of a (DAD–R)NiX2AlX'y(C2H5)3–y composition (instead of the aluminum atom may be a boron atom) were identified where R = –CH3 or –C3H7, X = Br, X' = Cl or –C2H5. The α-diimines radical-anions are included in the derivatives of aluminum or boron. It is found that there occur oxidation reactions between Ni(DAD–CH3)2 and aluminum organic compounds or boron derivatives, resulting in the formation of paramagnetic complexes. It is shown that there is no direct relationship between activity in polymerization or hydrogenation reactions and concentration of paramagnetic particles.
PACS: 76.30.–v Electron paramagnetic resonance and relaxation; PACS: 76.30.Lh Other ions and impurities; PACS: 76.30.Rn Free radicals.